FreeBSD/Linux Kernel Cross Reference
sys/cam/cam_xpt.c

     /*
      * Implementation of the Common Access Method Transport (XPT) layer.
      *
      * Copyright (c) 1997, 1998, 1999 Justin T. Gibbs.
      * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions, and the following disclaimer,
     *    without modification, immediately at the beginning of the file.
     * 2. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
     * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/types.h>
    #include <sys/malloc.h>
    #include <sys/kernel.h>
    #include <sys/time.h>
    #include <sys/conf.h>
    #include <sys/fcntl.h>
    #include <sys/md5.h>
    #include <sys/devicestat.h>
    #include <sys/interrupt.h>
    #include <sys/bus.h>
    
    #ifdef PC98
    #include <pc98/pc98/pc98_machdep.h>     /* geometry translation */
    #endif
    
    #include <machine/clock.h>
    #include <machine/ipl.h>
    
    #include <cam/cam.h>
    #include <cam/cam_ccb.h>
    #include <cam/cam_periph.h>
    #include <cam/cam_sim.h>
    #include <cam/cam_xpt.h>
    #include <cam/cam_xpt_sim.h>
    #include <cam/cam_xpt_periph.h>
    #include <cam/cam_debug.h>
    
    #include <cam/scsi/scsi_all.h>
    #include <cam/scsi/scsi_message.h>
    #include <cam/scsi/scsi_pass.h>
    #include <machine/stdarg.h>     /* for xpt_print below */
    #include "opt_cam.h"
    
    /* Datastructures internal to the xpt layer */
    
    /*
     * Definition of an async handler callback block.  These are used to add
     * SIMs and peripherals to the async callback lists.
     */
    struct async_node {
            SLIST_ENTRY(async_node) links;
            u_int32_t       event_enable;   /* Async Event enables */
            void            (*callback)(void *arg, u_int32_t code,
                                        struct cam_path *path, void *args);
            void            *callback_arg;
    };
    
    SLIST_HEAD(async_list, async_node);
    SLIST_HEAD(periph_list, cam_periph);
    static STAILQ_HEAD(highpowerlist, ccb_hdr) highpowerq;
    
    /*
     * This is the maximum number of high powered commands (e.g. start unit)
     * that can be outstanding at a particular time.
     */
    #ifndef CAM_MAX_HIGHPOWER
    #define CAM_MAX_HIGHPOWER  4
    #endif
    
    /* number of high powered commands that can go through right now */
    static int num_highpower = CAM_MAX_HIGHPOWER;
    
    /*
     * Structure for queueing a device in a run queue.
     * There is one run queue for allocating new ccbs,
     * and another for sending ccbs to the controller.
     */
   struct cam_ed_qinfo {
           cam_pinfo pinfo;
           struct    cam_ed *device;
   };
   
   /*
    * The CAM EDT (Existing Device Table) contains the device information for
    * all devices for all busses in the system.  The table contains a
    * cam_ed structure for each device on the bus.
    */
   struct cam_ed {
           TAILQ_ENTRY(cam_ed) links;
           struct  cam_ed_qinfo alloc_ccb_entry;
           struct  cam_ed_qinfo send_ccb_entry;
           struct  cam_et   *target;
           lun_id_t         lun_id;
           struct  camq drvq;              /*
                                            * Queue of type drivers wanting to do
                                            * work on this device.
                                            */
           struct  cam_ccbq ccbq;          /* Queue of pending ccbs */
           struct  async_list asyncs;      /* Async callback info for this B/T/L */
           struct  periph_list periphs;    /* All attached devices */
           u_int   generation;             /* Generation number */
           struct  cam_periph *owner;      /* Peripheral driver's ownership tag */
           struct  xpt_quirk_entry *quirk; /* Oddities about this device */
                                           /* Storage for the inquiry data */
           struct  scsi_inquiry_data inq_data;
           u_int8_t         inq_flags;     /*
                                            * Current settings for inquiry flags.
                                            * This allows us to override settings
                                            * like disconnection and tagged
                                            * queuing for a device.
                                            */
           u_int8_t         queue_flags;   /* Queue flags from the control page */
           u_int8_t         serial_num_len;
           u_int8_t         *serial_num;
           u_int32_t        qfrozen_cnt;
           u_int32_t        flags;
   #define CAM_DEV_UNCONFIGURED            0x01
   #define CAM_DEV_REL_TIMEOUT_PENDING     0x02
   #define CAM_DEV_REL_ON_COMPLETE         0x04
   #define CAM_DEV_REL_ON_QUEUE_EMPTY      0x08
   #define CAM_DEV_RESIZE_QUEUE_NEEDED     0x10
   #define CAM_DEV_TAG_AFTER_COUNT         0x20
   #define CAM_DEV_INQUIRY_DATA_VALID      0x40
           u_int32_t        tag_delay_count;
   #define CAM_TAG_DELAY_COUNT             5
           u_int32_t        refcount;
           struct           callout_handle c_handle;
   };
   
   /*
    * Each target is represented by an ET (Existing Target).  These
    * entries are created when a target is successfully probed with an
    * identify, and removed when a device fails to respond after a number
    * of retries, or a bus rescan finds the device missing.
    */
   struct cam_et { 
           TAILQ_HEAD(, cam_ed) ed_entries;
           TAILQ_ENTRY(cam_et) links;
           struct  cam_eb  *bus;   
           target_id_t     target_id;
           u_int32_t       refcount;       
           u_int           generation;
           struct          timeval last_reset;
   };
   
   /*
    * Each bus is represented by an EB (Existing Bus).  These entries
    * are created by calls to xpt_bus_register and deleted by calls to
    * xpt_bus_deregister.
    */
   struct cam_eb { 
           TAILQ_HEAD(, cam_et) et_entries;
           TAILQ_ENTRY(cam_eb)  links;
           path_id_t            path_id;
           struct cam_sim       *sim;
           struct timeval       last_reset;
           u_int32_t            flags;
   #define CAM_EB_RUNQ_SCHEDULED   0x01
           u_int32_t            refcount;
           u_int                generation;
   };
   
   struct cam_path {
           struct cam_periph *periph;
           struct cam_eb     *bus;
           struct cam_et     *target;
           struct cam_ed     *device;
   };
   
   struct xpt_quirk_entry {
           struct scsi_inquiry_pattern inq_pat;
           u_int8_t quirks;
   #define CAM_QUIRK_NOLUNS        0x01
   #define CAM_QUIRK_NOSERIAL      0x02
   #define CAM_QUIRK_HILUNS        0x04
           u_int mintags;
           u_int maxtags;
   };
   #define CAM_SCSI2_MAXLUN        8
   
   typedef enum {
           XPT_FLAG_OPEN           = 0x01
   } xpt_flags;
   
   struct xpt_softc {
           xpt_flags       flags;
           u_int32_t       generation;
   };
   
   static const char quantum[] = "QUANTUM";
   static const char sony[] = "SONY";
   static const char west_digital[] = "WDIGTL";
   static const char samsung[] = "SAMSUNG";
   static const char seagate[] = "SEAGATE";
   static const char microp[] = "MICROP";
   
   static struct xpt_quirk_entry xpt_quirk_table[] = 
   {
           {
                   /* Reports QUEUE FULL for temporary resource shortages */
                   { T_DIRECT, SIP_MEDIA_FIXED, quantum, "XP39100*", "*" },
                   /*quirks*/0, /*mintags*/24, /*maxtags*/32
           },
           {
                   /* Reports QUEUE FULL for temporary resource shortages */
                   { T_DIRECT, SIP_MEDIA_FIXED, quantum, "XP34550*", "*" },
                   /*quirks*/0, /*mintags*/24, /*maxtags*/32
           },
           {
                   /* Reports QUEUE FULL for temporary resource shortages */
                   { T_DIRECT, SIP_MEDIA_FIXED, quantum, "XP32275*", "*" },
                   /*quirks*/0, /*mintags*/24, /*maxtags*/32
           },
           {
                   /* Broken tagged queuing drive */
                   { T_DIRECT, SIP_MEDIA_FIXED, microp, "4421-07*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Broken tagged queuing drive */
                   { T_DIRECT, SIP_MEDIA_FIXED, "HP", "C372*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Broken tagged queuing drive */
                   { T_DIRECT, SIP_MEDIA_FIXED, microp, "3391*", "x43h" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Unfortunately, the Quantum Atlas III has the same
                    * problem as the Atlas II drives above.
                    * Reported by: "Johan Granlund" <johan@granlund.nu>
                    *
                    * For future reference, the drive with the problem was:
                    * QUANTUM QM39100TD-SW N1B0
                    * 
                    * It's possible that Quantum will fix the problem in later
                    * firmware revisions.  If that happens, the quirk entry
                    * will need to be made specific to the firmware revisions
                    * with the problem.
                    * 
                    */
                   /* Reports QUEUE FULL for temporary resource shortages */
                   { T_DIRECT, SIP_MEDIA_FIXED, quantum, "QM39100*", "*" },
                   /*quirks*/0, /*mintags*/24, /*maxtags*/32
           },
           {
                   /*
                    * 18 Gig Atlas III, same problem as the 9G version.
                    * Reported by: Andre Albsmeier
                    *              <andre.albsmeier@mchp.siemens.de>
                    *
                    * For future reference, the drive with the problem was:
                    * QUANTUM QM318000TD-S N491
                    */
                   /* Reports QUEUE FULL for temporary resource shortages */
                   { T_DIRECT, SIP_MEDIA_FIXED, quantum, "QM318000*", "*" },
                   /*quirks*/0, /*mintags*/24, /*maxtags*/32
           },
           {
                   /*
                    * Broken tagged queuing drive
                    * Reported by: Bret Ford <bford@uop.cs.uop.edu>
                    *         and: Martin Renters <martin@tdc.on.ca>
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, seagate, "ST410800*", "71*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
                   /*
                    * The Seagate Medalist Pro drives have very poor write
                    * performance with anything more than 2 tags.
                    * 
                    * Reported by:  Paul van der Zwan <paulz@trantor.xs4all.nl>
                    * Drive:  <SEAGATE ST36530N 1444>
                    *
                    * Reported by:  Jeremy Lea <reg@shale.csir.co.za>
                    * Drive:  <SEAGATE ST34520W 1281>
                    *
                    * No one has actually reported that the 9G version
                    * (ST39140*) of the Medalist Pro has the same problem, but
                    * we're assuming that it does because the 4G and 6.5G
                    * versions of the drive are broken.
                    */
           {
                   { T_DIRECT, SIP_MEDIA_FIXED, seagate, "ST34520*", "*"},
                   /*quirks*/0, /*mintags*/2, /*maxtags*/2
           },
           {
                   { T_DIRECT, SIP_MEDIA_FIXED, seagate, "ST36530*", "*"},
                   /*quirks*/0, /*mintags*/2, /*maxtags*/2
           },
           {
                   { T_DIRECT, SIP_MEDIA_FIXED, seagate, "ST39140*", "*"},
                   /*quirks*/0, /*mintags*/2, /*maxtags*/2
           },
           {
                   /*
                    * Slow when tagged queueing is enabled.  Write performance
                    * steadily drops off with more and more concurrent
                    * transactions.  Best sequential write performance with
                    * tagged queueing turned off and write caching turned on.
                    *
                    * PR:  kern/10398
                    * Submitted by:  Hideaki Okada <hokada@isl.melco.co.jp>
                    * Drive:  DCAS-34330 w/ "S65A" firmware.
                    *
                    * The drive with the problem had the "S65A" firmware
                    * revision, and has also been reported (by Stephen J.
                    * Roznowski <sjr@home.net>) for a drive with the "S61A"
                    * firmware revision.
                    *
                    * Although no one has reported problems with the 2 gig
                    * version of the DCAS drive, the assumption is that it
                    * has the same problems as the 4 gig version.  Therefore
                    * this quirk entries disables tagged queueing for all
                    * DCAS drives.
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, "IBM", "DCAS*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Broken tagged queuing drive */
                   { T_DIRECT, SIP_MEDIA_REMOVABLE, "iomega", "jaz*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Broken tagged queuing drive */ 
                   { T_DIRECT, SIP_MEDIA_FIXED, "CONNER", "CFP2107*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Does not support other than LUN 0 */
                   { T_DIRECT, SIP_MEDIA_FIXED, "VMware*", "*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/2, /*maxtags*/255
           },
           {
                   /*
                    * Broken tagged queuing drive.
                    * Submitted by:
                    * NAKAJI Hiroyuki <nakaji@zeisei.dpri.kyoto-u.ac.jp>
                    * in PR kern/9535
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, samsung, "WN34324U*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Slow when tagged queueing is enabled. (1.5MB/sec versus
                    * 8MB/sec.)
                    * Submitted by: Andrew Gallatin <gallatin@cs.duke.edu>
                    * Best performance with these drives is achieved with
                    * tagged queueing turned off, and write caching turned on.
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, west_digital, "WDE*", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Slow when tagged queueing is enabled. (1.5MB/sec versus
                    * 8MB/sec.)
                    * Submitted by: Andrew Gallatin <gallatin@cs.duke.edu>
                    * Best performance with these drives is achieved with
                    * tagged queueing turned off, and write caching turned on.
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, west_digital, "ENTERPRISE", "*" },
                   /*quirks*/0, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Doesn't handle queue full condition correctly,
                    * so we need to limit maxtags to what the device
                    * can handle instead of determining this automatically.
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, samsung, "WN321010S*", "*" },
                   /*quirks*/0, /*mintags*/2, /*maxtags*/32
           },
           {
                   /* Really only one LUN */
                   { T_ENCLOSURE, SIP_MEDIA_FIXED, "SUN", "SENA", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /* I can't believe we need a quirk for DPT volumes. */
                   { T_ANY, SIP_MEDIA_FIXED|SIP_MEDIA_REMOVABLE, "DPT", "*", "*" },
                   CAM_QUIRK_NOSERIAL|CAM_QUIRK_NOLUNS,
                   /*mintags*/0, /*maxtags*/255
           },
           {
                   /*
                    * Many Sony CDROM drives don't like multi-LUN probing.
                    */
                   { T_CDROM, SIP_MEDIA_REMOVABLE, sony, "CD-ROM CDU*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * This drive doesn't like multiple LUN probing.
                    * Submitted by:  Parag Patel <parag@cgt.com>
                    */
                   { T_WORM, SIP_MEDIA_REMOVABLE, sony, "CD-R   CDU9*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   { T_WORM, SIP_MEDIA_REMOVABLE, "YAMAHA", "CDR100*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * The 8200 doesn't like multi-lun probing, and probably
                    * don't like serial number requests either.
                    */
                   {
                           T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "EXABYTE",
                           "EXB-8200*", "*"
                   },
                   CAM_QUIRK_NOSERIAL|CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Let's try the same as above, but for a drive that says
                    * it's an IPL-6860 but is actually an EXB 8200.
                    */
                   {
                           T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "EXABYTE",
                           "IPL-6860*", "*"
                   },
                   CAM_QUIRK_NOSERIAL|CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * These Hitachi drives don't like multi-lun probing.
                    * The PR submitter has a DK319H, but says that the Linux
                    * kernel has a similar work-around for the DK312 and DK314,
                    * so all DK31* drives are quirked here.
                    * PR:            misc/18793
                    * Submitted by:  Paul Haddad <paul@pth.com>
                    */
                   { T_DIRECT, SIP_MEDIA_FIXED, "HITACHI", "DK31*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/2, /*maxtags*/255
           },
           {
                   /*
                    * This old revision of the TDC3600 is also SCSI-1, and
                    * hangs upon serial number probing.
                    */
                   {
                           T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
                           " TDC 3600", "U07:"
                   },
                   CAM_QUIRK_NOSERIAL, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Would repond to all LUNs if asked for.
                    */
                   {
                           T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "CALIPER",
                           "CP150", "*"
                   },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /*
                    * Would repond to all LUNs if asked for.
                    */
                   {
                           T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "KENNEDY",
                           "96X2*", "*"
                   },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Submitted by: Matthew Dodd <winter@jurai.net> */
                   { T_PROCESSOR, SIP_MEDIA_FIXED, "Cabletrn", "EA41*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Submitted by: Matthew Dodd <winter@jurai.net> */
                   { T_PROCESSOR, SIP_MEDIA_FIXED, "CABLETRN", "EA41*", "*" },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /* TeraSolutions special settings for TRC-22 RAID */
                   { T_DIRECT, SIP_MEDIA_FIXED, "TERASOLU", "TRC-22", "*" },
                     /*quirks*/0, /*mintags*/55, /*maxtags*/255
           },
           {
                   /* Veritas Storage Appliance */
                   { T_DIRECT, SIP_MEDIA_FIXED, "VERITAS", "*", "*" },
                     CAM_QUIRK_HILUNS, /*mintags*/2, /*maxtags*/1024
           },
           {
                   /*
                    * Would respond to all LUNs.  Device type and removable
                    * flag are jumper-selectable.
                    */
                   { T_ANY, SIP_MEDIA_REMOVABLE|SIP_MEDIA_FIXED, "MaxOptix",
                     "Tahiti 1", "*"
                   },
                   CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/
           },
           {
                   /* Default tagged queuing parameters for all devices */
                   {
                     T_ANY, SIP_MEDIA_REMOVABLE|SIP_MEDIA_FIXED,
                     /*vendor*/"*", /*product*/"*", /*revision*/"*"
                   },
                   /*quirks*/0, /*mintags*/2, /*maxtags*/255
           },
   };
   
   static const int xpt_quirk_table_size =
           sizeof(xpt_quirk_table) / sizeof(*xpt_quirk_table);
   
   typedef enum {
           DM_RET_COPY             = 0x01,
           DM_RET_FLAG_MASK        = 0x0f,
           DM_RET_NONE             = 0x00,
           DM_RET_STOP             = 0x10,
           DM_RET_DESCEND          = 0x20,
           DM_RET_ERROR            = 0x30,
           DM_RET_ACTION_MASK      = 0xf0
   } dev_match_ret;
   
   typedef enum {
           XPT_DEPTH_BUS,
           XPT_DEPTH_TARGET,
           XPT_DEPTH_DEVICE,
           XPT_DEPTH_PERIPH
   } xpt_traverse_depth;
   
   struct xpt_traverse_config {
           xpt_traverse_depth      depth;
           void                    *tr_func;
           void                    *tr_arg;
   };
   
   typedef int     xpt_busfunc_t (struct cam_eb *bus, void *arg);
   typedef int     xpt_targetfunc_t (struct cam_et *target, void *arg);
   typedef int     xpt_devicefunc_t (struct cam_ed *device, void *arg);
   typedef int     xpt_periphfunc_t (struct cam_periph *periph, void *arg);
   typedef int     xpt_pdrvfunc_t (struct periph_driver **pdrv, void *arg);
   
   /* Transport layer configuration information */
   static struct xpt_softc xsoftc;
   
   /* Queues for our software interrupt handler */
   typedef TAILQ_HEAD(cam_isrq, ccb_hdr) cam_isrq_t;
   static cam_isrq_t cam_bioq;
   static cam_isrq_t cam_netq;
   
   /* "Pool" of inactive ccbs managed by xpt_alloc_ccb and xpt_free_ccb */
   static SLIST_HEAD(,ccb_hdr) ccb_freeq;
   static u_int xpt_max_ccbs;      /*
                                    * Maximum size of ccb pool.  Modified as
                                    * devices are added/removed or have their
                                    * opening counts changed.
                                    */
   static u_int xpt_ccb_count;     /* Current count of allocated ccbs */
   
   struct cam_periph *xpt_periph;
   
   static periph_init_t xpt_periph_init;
   
   static periph_init_t probe_periph_init;
   
   static struct periph_driver xpt_driver =
   {
           xpt_periph_init, "xpt",
           TAILQ_HEAD_INITIALIZER(xpt_driver.units)
   };
   
   static struct periph_driver probe_driver =
   {
           probe_periph_init, "probe",
           TAILQ_HEAD_INITIALIZER(probe_driver.units)
   };
   
   DATA_SET(periphdriver_set, xpt_driver);
   DATA_SET(periphdriver_set, probe_driver);
   
   #define XPT_CDEV_MAJOR 104
   
   static d_open_t xptopen;
   static d_close_t xptclose;
   static d_ioctl_t xptioctl;
   
   static struct cdevsw xpt_cdevsw = {
           /* open */      xptopen,
           /* close */     xptclose,
           /* read */      noread,
           /* write */     nowrite,
           /* ioctl */     xptioctl,
           /* poll */      nopoll,
           /* mmap */      nommap,
           /* strategy */  nostrategy,
           /* name */      "xpt",
           /* maj */       XPT_CDEV_MAJOR,
           /* dump */      nodump,
           /* psize */     nopsize,
           /* flags */     0,
           /* bmaj */      -1
   };
   
   static struct intr_config_hook *xpt_config_hook;
   
   /* Registered busses */
   static TAILQ_HEAD(,cam_eb) xpt_busses;
   static u_int bus_generation;
   
   /* Storage for debugging datastructures */
   #ifdef  CAMDEBUG
   struct cam_path *cam_dpath;
   u_int32_t cam_dflags;
   u_int32_t cam_debug_delay;
   #endif
   
   #if defined(CAM_DEBUG_FLAGS) && !defined(CAMDEBUG)
   #error "You must have options CAMDEBUG to use options CAM_DEBUG_FLAGS"
   #endif
   
   /*
    * In order to enable the CAM_DEBUG_* options, the user must have CAMDEBUG
    * enabled.  Also, the user must have either none, or all of CAM_DEBUG_BUS,
    * CAM_DEBUG_TARGET, and CAM_DEBUG_LUN specified.
    */
   #if defined(CAM_DEBUG_BUS) || defined(CAM_DEBUG_TARGET) \
       || defined(CAM_DEBUG_LUN)
   #ifdef CAMDEBUG
   #if !defined(CAM_DEBUG_BUS) || !defined(CAM_DEBUG_TARGET) \
       || !defined(CAM_DEBUG_LUN)
   #error "You must define all or none of CAM_DEBUG_BUS, CAM_DEBUG_TARGET \
           and CAM_DEBUG_LUN"
   #endif /* !CAM_DEBUG_BUS || !CAM_DEBUG_TARGET || !CAM_DEBUG_LUN */
   #else /* !CAMDEBUG */
   #error "You must use options CAMDEBUG if you use the CAM_DEBUG_* options"
   #endif /* CAMDEBUG */
   #endif /* CAM_DEBUG_BUS || CAM_DEBUG_TARGET || CAM_DEBUG_LUN */
   
   /* Our boot-time initialization hook */
   static int cam_module_event_handler(module_t, int /*modeventtype_t*/, void *);
   
   static moduledata_t cam_moduledata = {
           "cam",
           cam_module_event_handler,
           NULL
   };
   
   static void     xpt_init(void *);
   
   DECLARE_MODULE(cam, cam_moduledata, SI_SUB_CONFIGURE, SI_ORDER_SECOND);
   MODULE_VERSION(cam, 1);
   
   
   static cam_status       xpt_compile_path(struct cam_path *new_path,
                                            struct cam_periph *perph,
                                            path_id_t path_id,
                                            target_id_t target_id,
                                            lun_id_t lun_id);
   
   static void             xpt_release_path(struct cam_path *path);
   
   static void             xpt_async_bcast(struct async_list *async_head,
                                           u_int32_t async_code,
                                           struct cam_path *path,
                                           void *async_arg);
   static void             xpt_dev_async(u_int32_t async_code,
                                         struct cam_eb *bus,
                                         struct cam_et *target,
                                         struct cam_ed *device,
                                         void *async_arg);
   static path_id_t xptnextfreepathid(void);
   static path_id_t xptpathid(const char *sim_name, int sim_unit, int sim_bus);
   static union ccb *xpt_get_ccb(struct cam_ed *device);
   static int       xpt_schedule_dev(struct camq *queue, cam_pinfo *dev_pinfo,
                                     u_int32_t new_priority);
   static void      xpt_run_dev_allocq(struct cam_eb *bus);
   static void      xpt_run_dev_sendq(struct cam_eb *bus);
   static timeout_t xpt_release_devq_timeout;
   static timeout_t xpt_release_simq_timeout;
   static void      xpt_release_bus(struct cam_eb *bus);
   static void      xpt_release_devq_device(struct cam_ed *dev, u_int count,
                                            int run_queue);
   static struct cam_et*
                    xpt_alloc_target(struct cam_eb *bus, target_id_t target_id);
   static void      xpt_release_target(struct cam_eb *bus, struct cam_et *target);
   static struct cam_ed*
                    xpt_alloc_device(struct cam_eb *bus, struct cam_et *target,
                                     lun_id_t lun_id);
   static void      xpt_release_device(struct cam_eb *bus, struct cam_et *target,
                                       struct cam_ed *device);
   static u_int32_t xpt_dev_ccbq_resize(struct cam_path *path, int newopenings);
   static struct cam_eb*
                    xpt_find_bus(path_id_t path_id);
   static struct cam_et*
                    xpt_find_target(struct cam_eb *bus, target_id_t target_id);
   static struct cam_ed*
                    xpt_find_device(struct cam_et *target, lun_id_t lun_id);
   static void      xpt_scan_bus(struct cam_periph *periph, union ccb *ccb);
   static void      xpt_scan_lun(struct cam_periph *periph,
                                 struct cam_path *path, cam_flags flags,
                                 union ccb *ccb);
   static void      xptscandone(struct cam_periph *periph, union ccb *done_ccb);
   static xpt_busfunc_t    xptconfigbuscountfunc;
   static xpt_busfunc_t    xptconfigfunc;
   static void      xpt_config(void *arg);
   static xpt_devicefunc_t xptpassannouncefunc;
   static void      xpt_finishconfig(struct cam_periph *periph, union ccb *ccb);
   static void      xptaction(struct cam_sim *sim, union ccb *work_ccb);
   static void      xptpoll(struct cam_sim *sim);
   static swihand_t swi_camnet;
   static swihand_t swi_cambio;
   static void      camisr(cam_isrq_t *queue);
   #if 0
   static void      xptstart(struct cam_periph *periph, union ccb *work_ccb);
   static void      xptasync(struct cam_periph *periph,
                             u_int32_t code, cam_path *path);
   #endif
   static dev_match_ret    xptbusmatch(struct dev_match_pattern *patterns,
                                       int num_patterns, struct cam_eb *bus);
   static dev_match_ret    xptdevicematch(struct dev_match_pattern *patterns,
                                          int num_patterns, struct cam_ed *device);
   static dev_match_ret    xptperiphmatch(struct dev_match_pattern *patterns,
                                          int num_patterns,
                                          struct cam_periph *periph);
   static xpt_busfunc_t    xptedtbusfunc;
   static xpt_targetfunc_t xptedttargetfunc;
   static xpt_devicefunc_t xptedtdevicefunc;
   static xpt_periphfunc_t xptedtperiphfunc;
   static xpt_pdrvfunc_t   xptplistpdrvfunc;
   static xpt_periphfunc_t xptplistperiphfunc;
   static int              xptedtmatch(struct ccb_dev_match *cdm);
   static int              xptperiphlistmatch(struct ccb_dev_match *cdm);
   static int              xptbustraverse(struct cam_eb *start_bus,
                                          xpt_busfunc_t *tr_func, void *arg);
   static int              xpttargettraverse(struct cam_eb *bus,
                                             struct cam_et *start_target,
                                             xpt_targetfunc_t *tr_func, void *arg);
   static int              xptdevicetraverse(struct cam_et *target,
                                             struct cam_ed *start_device,
                                             xpt_devicefunc_t *tr_func, void *arg);
   static int              xptperiphtraverse(struct cam_ed *device,
                                             struct cam_periph *start_periph,
                                             xpt_periphfunc_t *tr_func, void *arg);
   static int              xptpdrvtraverse(struct periph_driver **start_pdrv,
                                           xpt_pdrvfunc_t *tr_func, void *arg);
   static int              xptpdperiphtraverse(struct periph_driver **pdrv,
                                               struct cam_periph *start_periph,
                                               xpt_periphfunc_t *tr_func,
                                               void *arg);
   static xpt_busfunc_t    xptdefbusfunc;
   static xpt_targetfunc_t xptdeftargetfunc;
   static xpt_devicefunc_t xptdefdevicefunc;
   static xpt_periphfunc_t xptdefperiphfunc;
   static int              xpt_for_all_busses(xpt_busfunc_t *tr_func, void *arg);
   #ifdef notusedyet
   static int              xpt_for_all_targets(xpt_targetfunc_t *tr_func,
                                               void *arg);
   #endif
   static int              xpt_for_all_devices(xpt_devicefunc_t *tr_func,
                                               void *arg);
   #ifdef notusedyet
   static int              xpt_for_all_periphs(xpt_periphfunc_t *tr_func,
                                               void *arg);
   #endif
   static xpt_devicefunc_t xptsetasyncfunc;
   static xpt_busfunc_t    xptsetasyncbusfunc;
   static cam_status       xptregister(struct cam_periph *periph,
                                       void *arg);
   static cam_status       proberegister(struct cam_periph *periph,
                                         void *arg);
   static void      probeschedule(struct cam_periph *probe_periph);
   static void      probestart(struct cam_periph *periph, union ccb *start_ccb);
   static void      proberequestdefaultnegotiation(struct cam_periph *periph);
   static void      probedone(struct cam_periph *periph, union ccb *done_ccb);
   static void      probecleanup(struct cam_periph *periph);
   static void      xpt_find_quirk(struct cam_ed *device);
   static void      xpt_set_transfer_settings(struct ccb_trans_settings *cts,
                                              struct cam_ed *device,
                                              int async_update);
   static void      xpt_toggle_tags(struct cam_path *path);
   static void      xpt_start_tags(struct cam_path *path);
   static __inline int xpt_schedule_dev_allocq(struct cam_eb *bus,
                                               struct cam_ed *dev);
   static __inline int xpt_schedule_dev_sendq(struct cam_eb *bus,
                                              struct cam_ed *dev);
   static __inline int periph_is_queued(struct cam_periph *periph);
   static __inline int device_is_alloc_queued(struct cam_ed *device);
   static __inline int device_is_send_queued(struct cam_ed *device);
   static __inline int dev_allocq_is_runnable(struct cam_devq *devq);
   
   static __inline int
   xpt_schedule_dev_allocq(struct cam_eb *bus, struct cam_ed *dev)
   {
           int retval;
   
           if (dev->ccbq.devq_openings > 0) {
                   if ((dev->flags & CAM_DEV_RESIZE_QUEUE_NEEDED) != 0) {
                           cam_ccbq_resize(&dev->ccbq,
                                           dev->ccbq.dev_openings
                                           + dev->ccbq.dev_active);
                           dev->flags &= ~CAM_DEV_RESIZE_QUEUE_NEEDED;
                   }
                   /*
                    * The priority of a device waiting for CCB resources
                    * is that of the the highest priority peripheral driver
                    * enqueued.
                    */
                   retval = xpt_schedule_dev(&bus->sim->devq->alloc_queue,
                                             &dev->alloc_ccb_entry.pinfo,
                                             CAMQ_GET_HEAD(&dev->drvq)->priority); 
           } else {
                   retval = 0;
           }
   
           return (retval);
   }
   
   static __inline int
   xpt_schedule_dev_sendq(struct cam_eb *bus, struct cam_ed *dev)
   {
           int     retval;
   
           if (dev->ccbq.dev_openings > 0) {
                   /*
                    * The priority of a device waiting for controller
                    * resources is that of the the highest priority CCB
                    * enqueued.
                    */
                   retval =
                       xpt_schedule_dev(&bus->sim->devq->send_queue,
                                        &dev->send_ccb_entry.pinfo,
                                        CAMQ_GET_HEAD(&dev->ccbq.queue)->priority);
           } else {
                   retval = 0;
           }
           return (retval);
   }
   
   static __inline int
   periph_is_queued(struct cam_periph *periph)
   {
           return (periph->pinfo.index != CAM_UNQUEUED_INDEX);
   }
   
   static __inline int
   device_is_alloc_queued(struct cam_ed *device)
   {
           return (device->alloc_ccb_entry.pinfo.index != CAM_UNQUEUED_INDEX);
   }
   
   static __inline int
   device_is_send_queued(struct cam_ed *device)
   {
           return (device->send_ccb_entry.pinfo.index != CAM_UNQUEUED_INDEX);
   }
   
   static __inline int
   dev_allocq_is_runnable(struct cam_devq *devq)
   {
           /*
            * Have work to do.
            * Have space to do more work.
            * Allowed to do work.
            */
           return ((devq->alloc_queue.qfrozen_cnt == 0)
                && (devq->alloc_queue.entries > 0)
                && (devq->alloc_openings > 0));
   }
   
   static void
   xpt_periph_init()
   {
           make_dev(&xpt_cdevsw, 0, UID_ROOT, GID_OPERATOR, 0600, "xpt0");
   }
   
   static void
   probe_periph_init()
   {
   }
   
   
   static void
   xptdone(struct cam_periph *periph, union ccb *done_ccb)
   {
           /* Caller will release the CCB */
           wakeup(&done_ccb->ccb_h.cbfcnp);
   }
   
   static int
   xptopen(dev_t dev, int flags, int fmt, struct proc *p)
   {
           int unit;
   
           unit = minor(dev) & 0xff;
   
           /*
            * Only allow read-write access.
            */
           if (((flags & FWRITE) == 0) || ((flags & FREAD) == 0))
                   return(EPERM);
   
           /*
            * We don't allow nonblocking access.
            */
           if ((flags & O_NONBLOCK) != 0) {
                   printf("xpt%d: can't do nonblocking access\n", unit);
                   return(ENODEV);
           }
   
           /*
            * We only have one transport layer right now.  If someone accesses
            * us via something other than minor number 1, point out their
            * mistake.
            */
           if (unit != 0) {
                   printf("xptopen: got invalid xpt unit %d\n", unit);
                   return(ENXIO);
           }
   
           /* Mark ourselves open */
           xsoftc.flags |= XPT_FLAG_OPEN;
           
           return(0);
   }
   
   static int
   xptclose(dev_t dev, int flag, int fmt, struct proc *p)
   {
           int unit;
   
           unit = minor(dev) & 0xff;
   
           /*
            * We only have one transport layer right now.  If someone accesses
            * us via something other than minor number 1, point out their
            * mistake.
            */
           if (unit != 0) {
                   printf("xptclose: got invalid xpt unit %d\n", unit);
                   return(ENXIO);
           }
   
           /* Mark ourselves closed */
           xsoftc.flags &= ~XPT_FLAG_OPEN;
   
           return(0);
   }
   
   static int
   xptioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
   {
           int unit, error;
   
           error = 0;
           unit = minor(dev) & 0xff;
   
           /*
            * We only have one transport layer right now.  If someone accesses
            * us via something other than minor number 1, point out their
            * mistake.
            */
           if (unit != 0) {
                   printf("xptioctl: got invalid xpt unit %d\n", unit);
                   return(ENXIO);
           }
   
           switch(cmd) {
           /*
            * For the transport layer CAMIOCOMMAND ioctl, we really only want
            * to accept CCB types that don't quite make sense to send through a
            * passthrough driver.
            */
           case CAMIOCOMMAND: {
                   union ccb *ccb;
                   union ccb *inccb;
  
                  inccb = (union ccb *)addr;
  
                  switch(inccb->ccb_h.func_code) {
                  case XPT_SCAN_BUS:
                  case XPT_RESET_BUS:
                          if ((inccb->ccb_h.target_id != CAM_TARGET_WILDCARD)
                           || (inccb->ccb_h.target_lun != CAM_LUN_WILDCARD)) {
                                  error = EINVAL;
                                  break;
                          }
                          /* FALLTHROUGH */
                  case XPT_PATH_INQ:
                  case XPT_ENG_INQ:
                  case XPT_SCAN_LUN:
  
                          ccb = xpt_alloc_ccb();
  
                          /*
                           * Create a path using the bus, target, and lun the
                           * user passed in.
                           */
                          if (xpt_create_path(&ccb->ccb_h.path, xpt_periph,
                                              inccb->ccb_h.path_id,
                                              inccb->ccb_h.target_id,
                                              inccb->ccb_h.target_lun) !=
                                              CAM_REQ_CMP){
                                  error = EINVAL;
                                  xpt_free_ccb(ccb);
                                  break;
                          }
                          /* Ensure all of our fields are correct */
                          xpt_setup_ccb(&ccb->ccb_h, ccb->ccb_h.path,
                                        inccb->ccb_h.pinfo.priority);
                          xpt_merge_ccb(ccb, inccb);
                          ccb->ccb_h.cbfcnp = xptdone;
                          cam_periph_runccb(ccb, NULL, 0, 0, NULL);
                          bcopy(ccb, inccb, sizeof(union ccb));
                          xpt_free_path(ccb->ccb_h.path);
                          xpt_free_ccb(ccb);
                          break;
  
                  case XPT_DEBUG: {
                          union ccb ccb;
  
                          /*
                           * This is an immediate CCB, so it's okay to
                           * allocate it on the stack.
                           */
  
                          /*
                           * Create a path using the bus, target, and lun the
                           * user passed in.
                           */
                          if (xpt_create_path(&ccb.ccb_h.path, xpt_periph,
                                              inccb->ccb_h.path_id,
                                              inccb->ccb_h.target_id,
                                              inccb->ccb_h.target_lun) !=
                                              CAM_REQ_CMP){
                                  error = EINVAL;
                                  break;
                          }
                          /* Ensure all of our fields are correct */
                          xpt_setup_ccb(&ccb.ccb_h, ccb.ccb_h.path,
                                        inccb->ccb_h.pinfo.priority);
                          xpt_merge_ccb(&ccb, inccb);
                          ccb.ccb_h.cbfcnp = xptdone;
                          xpt_action(&ccb);
                          bcopy(&ccb, inccb, sizeof(union ccb));
                          xpt_free_path(ccb.ccb_h.path);
                          break;
  
                  }
                  case XPT_DEV_MATCH: {
                          struct cam_periph_map_info mapinfo;
                          struct cam_path *old_path;
  
                          /*
                           * We can't deal with physical addresses for this
                           * type of transaction.
                           */
                          if (inccb->ccb_h.flags & CAM_DATA_PHYS) {
                                  error = EINVAL;
                                  break;
                          }
  
                          /*
                           * Save this in case the caller had it set to
                           * something in particular.
                           */
                          old_path = inccb->ccb_h.path;
  
                          /*
                           * We really don't need a path for the matching
                           * code.  The path is needed because of the
                           * debugging statements in xpt_action().  They
                           * assume that the CCB has a valid path.
                           */
                          inccb->ccb_h.path = xpt_periph->path;
  
                          bzero(&mapinfo, sizeof(mapinfo));
  
                          /*
                           * Map the pattern and match buffers into kernel
                           * virtual address space.
                           */
                          error = cam_periph_mapmem(inccb, &mapinfo);
  
                          if (error) {
                                  inccb->ccb_h.path = old_path;
                                  break;
                          }
  
                          /*
                           * This is an immediate CCB, we can send it on directly.
                           */
                          xpt_action(inccb);
  
                          /*
                           * Map the buffers back into user space.
                           */
                          cam_periph_unmapmem(inccb, &mapinfo);
  
                          inccb->ccb_h.path = old_path;
  
                          error = 0;
                          break;
                  }
                  default:
                          error = ENOTSUP;
                          break;
                  }
                  break;
          }
          /*
           * This is the getpassthru ioctl. It takes a XPT_GDEVLIST ccb as input,
           * with the periphal driver name and unit name filled in.  The other
           * fields don't really matter as input.  The passthrough driver name
           * ("pass"), and unit number are passed back in the ccb.  The current
           * device generation number, and the index into the device peripheral
           * driver list, and the status are also passed back.  Note that
           * since we do everything in one pass, unlike the XPT_GDEVLIST ccb,
           * we never return a status of CAM_GDEVLIST_LIST_CHANGED.  It is
           * (or rather should be) impossible for the device peripheral driver
           * list to change since we look at the whole thing in one pass, and
           * we do it with splcam protection.
           * 
           */
          case CAMGETPASSTHRU: {
                  union ccb *ccb;
                  struct cam_periph *periph;
                  struct periph_driver **p_drv;
                  char   *name;
                  int unit;
                  int cur_generation;
                  int base_periph_found;
                  int splbreaknum;
                  int s;
  
                  ccb = (union ccb *)addr;
                  unit = ccb->cgdl.unit_number;
                  name = ccb->cgdl.periph_name;
                  /*
                   * Every 100 devices, we want to drop our spl protection to
                   * give the software interrupt handler a chance to run.
                   * Most systems won't run into this check, but this should
                   * avoid starvation in the software interrupt handler in
                   * large systems.
                   */
                  splbreaknum = 100;
  
                  ccb = (union ccb *)addr;
  
                  base_periph_found = 0;
  
                  /*
                   * Sanity check -- make sure we don't get a null peripheral
                   * driver name.
                   */
                  if (*ccb->cgdl.periph_name == '\0') {
                          error = EINVAL;
                          break;
                  }
  
                  /* Keep the list from changing while we traverse it */
                  s = splcam();
  ptstartover:
                  cur_generation = xsoftc.generation;
  
                  /* first find our driver in the list of drivers */
                  for (p_drv = (struct periph_driver **)periphdriver_set.ls_items;
                       *p_drv != NULL; p_drv++)
                          if (strcmp((*p_drv)->driver_name, name) == 0)
                                  break;
  
                  if (*p_drv == NULL) {
                          splx(s);
                          ccb->ccb_h.status = CAM_REQ_CMP_ERR;
                          ccb->cgdl.status = CAM_GDEVLIST_ERROR;
                          *ccb->cgdl.periph_name = '\0';
                          ccb->cgdl.unit_number = 0;
                          error = ENOENT;
                          break;
                  }       
  
                  /*
                   * Run through every peripheral instance of this driver
                   * and check to see whether it matches the unit passed
                   * in by the user.  If it does, get out of the loops and
                   * find the passthrough driver associated with that
                   * peripheral driver.
                   */
                  for (periph = TAILQ_FIRST(&(*p_drv)->units); periph != NULL;
                       periph = TAILQ_NEXT(periph, unit_links)) {
  
                          if (periph->unit_number == unit) {
                                  break;
                          } else if (--splbreaknum == 0) {
                                  splx(s);
                                  s = splcam();
                                  splbreaknum = 100;
                                  if (cur_generation != xsoftc.generation)
                                         goto ptstartover;
                          }
                  }
                  /*
                   * If we found the peripheral driver that the user passed
                   * in, go through all of the peripheral drivers for that
                   * particular device and look for a passthrough driver.
                   */
                  if (periph != NULL) {
                          struct cam_ed *device;
                          int i;
  
                          base_periph_found = 1;
                          device = periph->path->device;
                          for (i = 0, periph = device->periphs.slh_first;
                               periph != NULL;
                               periph = periph->periph_links.sle_next, i++) {
                                  /*
                                   * Check to see whether we have a
                                   * passthrough device or not. 
                                   */
                                  if (strcmp(periph->periph_name, "pass") == 0) {
                                          /*
                                           * Fill in the getdevlist fields.
                                           */
                                          strcpy(ccb->cgdl.periph_name,
                                                 periph->periph_name);
                                          ccb->cgdl.unit_number =
                                                  periph->unit_number;
                                          if (periph->periph_links.sle_next)
                                                  ccb->cgdl.status =
                                                          CAM_GDEVLIST_MORE_DEVS;
                                          else
                                                  ccb->cgdl.status =
                                                         CAM_GDEVLIST_LAST_DEVICE;
                                          ccb->cgdl.generation =
                                                  device->generation;
                                          ccb->cgdl.index = i;
                                          /*
                                           * Fill in some CCB header fields
                                           * that the user may want.
                                           */
                                          ccb->ccb_h.path_id =
                                                  periph->path->bus->path_id;
                                          ccb->ccb_h.target_id =
                                                  periph->path->target->target_id;
                                          ccb->ccb_h.target_lun =
                                                  periph->path->device->lun_id;
                                          ccb->ccb_h.status = CAM_REQ_CMP;
                                          break;
                                  }
                          }
                  }
  
                  /*
                   * If the periph is null here, one of two things has
                   * happened.  The first possibility is that we couldn't
                   * find the unit number of the particular peripheral driver
                   * that the user is asking about.  e.g. the user asks for
                   * the passthrough driver for "da11".  We find the list of
                   * "da" peripherals all right, but there is no unit 11.
                   * The other possibility is that we went through the list
                   * of peripheral drivers attached to the device structure,
                   * but didn't find one with the name "pass".  Either way,
                   * we return ENOENT, since we couldn't find something.
                   */
                  if (periph == NULL) {
                          ccb->ccb_h.status = CAM_REQ_CMP_ERR;
                          ccb->cgdl.status = CAM_GDEVLIST_ERROR;
                          *ccb->cgdl.periph_name = '\0';
                          ccb->cgdl.unit_number = 0;
                          error = ENOENT;
                          /*
                           * It is unfortunate that this is even necessary,
                           * but there are many, many clueless users out there.
                           * If this is true, the user is looking for the
                           * passthrough driver, but doesn't have one in his
                           * kernel.
                           */
                          if (base_periph_found == 1) {
                                  printf("xptioctl: pass driver is not in the "
                                         "kernel\n");
                                  printf("xptioctl: put \"device pass0\" in "
                                         "your kernel config file\n");
                          }
                  }
                  splx(s);
                  break;
                  }
          default:
                  error = ENOTTY;
                  break;
          }
  
          return(error);
  }
  
  static int
  cam_module_event_handler(module_t mod, int what, void *arg)
  {
          if (what == MOD_LOAD) {
                  xpt_init(NULL);
          } else if (what == MOD_UNLOAD) {
                  return EBUSY;
          }
  
          return 0;
  }
  
  /* Functions accessed by the peripheral drivers */
  static void
  xpt_init(dummy)
          void *dummy;
  {
          struct cam_sim *xpt_sim;
          struct cam_path *path;
          struct cam_devq *devq;
          cam_status status;
  
          TAILQ_INIT(&xpt_busses);
          TAILQ_INIT(&cam_bioq);
          TAILQ_INIT(&cam_netq);
          SLIST_INIT(&ccb_freeq);
          STAILQ_INIT(&highpowerq);
  
          /*
           * The xpt layer is, itself, the equivelent of a SIM.
           * Allow 16 ccbs in the ccb pool for it.  This should
           * give decent parallelism when we probe busses and
           * perform other XPT functions.
           */
          devq = cam_simq_alloc(16);
          xpt_sim = cam_sim_alloc(xptaction,
                                  xptpoll,
                                  "xpt",
                                  /*softc*/NULL,
                                  /*unit*/0,
                                  /*max_dev_transactions*/0,
                                  /*max_tagged_dev_transactions*/0,
                                  devq);
          xpt_max_ccbs = 16;
                                  
          xpt_bus_register(xpt_sim, /*bus #*/0);
  
          /*
           * Looking at the XPT from the SIM layer, the XPT is
           * the equivelent of a peripheral driver.  Allocate
           * a peripheral driver entry for us.
           */
          if ((status = xpt_create_path(&path, NULL, CAM_XPT_PATH_ID,
                                        CAM_TARGET_WILDCARD,
                                        CAM_LUN_WILDCARD)) != CAM_REQ_CMP) {
                  printf("xpt_init: xpt_create_path failed with status %#x,"
                         " failing attach\n", status);
                  return;
          }
  
          cam_periph_alloc(xptregister, NULL, NULL, NULL, "xpt", CAM_PERIPH_BIO,
                           path, NULL, 0, NULL);
          xpt_free_path(path);
  
          xpt_sim->softc = xpt_periph;
  
          /*
           * Register a callback for when interrupts are enabled.
           */
          xpt_config_hook =
              (struct intr_config_hook *)malloc(sizeof(struct intr_config_hook),
                                                M_TEMP, M_NOWAIT | M_ZERO);
          if (xpt_config_hook == NULL) {
                  printf("xpt_init: Cannot malloc config hook "
                         "- failing attach\n");
                  return;
          }
  
          xpt_config_hook->ich_func = xpt_config;
          if (config_intrhook_establish(xpt_config_hook) != 0) {
                  free (xpt_config_hook, M_TEMP);
                  printf("xpt_init: config_intrhook_establish failed "
                         "- failing attach\n");
          }
  
          /* Install our software interrupt handlers */
          register_swi(SWI_CAMNET, swi_camnet);
          register_swi(SWI_CAMBIO, swi_cambio);
  }
  
  static cam_status
  xptregister(struct cam_periph *periph, void *arg)
  {
          if (periph == NULL) {
                  printf("xptregister: periph was NULL!!\n");
                  return(CAM_REQ_CMP_ERR);
          }
  
          periph->softc = NULL;
  
          xpt_periph = periph;
  
          return(CAM_REQ_CMP);
  }
  
  int32_t
  xpt_add_periph(struct cam_periph *periph)
  {
          struct cam_ed *device;
          int32_t  status;
          struct periph_list *periph_head;
  
          device = periph->path->device;
  
          periph_head = &device->periphs;
  
          status = CAM_REQ_CMP;
  
          if (device != NULL) {
                  int s;
  
                  /*
                   * Make room for this peripheral
                   * so it will fit in the queue
                   * when it's scheduled to run
                   */
                  s = splsoftcam();
                  status = camq_resize(&device->drvq,
                                       device->drvq.array_size + 1);
  
                  device->generation++;
  
                  SLIST_INSERT_HEAD(periph_head, periph, periph_links);
  
                  splx(s);
          }
  
          xsoftc.generation++;
  
          return (status);
  }
  
  void
  xpt_remove_periph(struct cam_periph *periph)
  {
          struct cam_ed *device;
  
          device = periph->path->device;
  
          if (device != NULL) {
                  int s;
                  struct periph_list *periph_head;
  
                  periph_head = &device->periphs;
                  
                  /* Release the slot for this peripheral */
                  s = splsoftcam();
                  camq_resize(&device->drvq, device->drvq.array_size - 1);
  
                  device->generation++;
  
                  SLIST_REMOVE(periph_head, periph, cam_periph, periph_links);
  
                  splx(s);
          }
  
          xsoftc.generation++;
  
  }
  
  void
  xpt_announce_periph(struct cam_periph *periph, char *announce_string)
  {
          int s;
          u_int mb;
          struct cam_path *path;
          struct ccb_trans_settings cts;
  
          path = periph->path;
          /*
           * To ensure that this is printed in one piece,
           * mask out CAM interrupts.
           */
          s = splsoftcam();
          printf("%s%d at %s%d bus %d target %d lun %d\n",
                 periph->periph_name, periph->unit_number,
                 path->bus->sim->sim_name,
                 path->bus->sim->unit_number,
                 path->bus->sim->bus_id,
                 path->target->target_id,
                 path->device->lun_id);
          printf("%s%d: ", periph->periph_name, periph->unit_number);
          scsi_print_inquiry(&path->device->inq_data);
          if ((bootverbose)
           && (path->device->serial_num_len > 0)) {
                  /* Don't wrap the screen  - print only the first 60 chars */
                  printf("%s%d: Serial Number %.60s\n", periph->periph_name,
                         periph->unit_number, path->device->serial_num);
          }
          xpt_setup_ccb(&cts.ccb_h, path, /*priority*/1);
          cts.ccb_h.func_code = XPT_GET_TRAN_SETTINGS;
          cts.flags = CCB_TRANS_CURRENT_SETTINGS;
          xpt_action((union ccb*)&cts);
          if (cts.ccb_h.status == CAM_REQ_CMP) {
                  u_int speed;
                  u_int freq;
  
                  if ((cts.valid & CCB_TRANS_SYNC_OFFSET_VALID) != 0
                    && cts.sync_offset != 0) {
                          freq = scsi_calc_syncsrate(cts.sync_period);
                          speed = freq;
                  } else {
                          struct ccb_pathinq cpi;
  
                          /* Ask the SIM for its base transfer speed */
                          xpt_setup_ccb(&cpi.ccb_h, path, /*priority*/1);
                          cpi.ccb_h.func_code = XPT_PATH_INQ;
                          xpt_action((union ccb *)&cpi);
  
                          speed = cpi.base_transfer_speed;
                          freq = 0;
                  }
                  if ((cts.valid & CCB_TRANS_BUS_WIDTH_VALID) != 0)
                          speed *= (0x01 << cts.bus_width);
                  mb = speed / 1000;
                  if (mb > 0)
                          printf("%s%d: %d.%03dMB/s transfers",
                                 periph->periph_name, periph->unit_number,
                                 mb, speed % 1000);
                  else
                          printf("%s%d: %dKB/s transfers", periph->periph_name,
                                 periph->unit_number, speed);
                  if ((cts.valid & CCB_TRANS_SYNC_OFFSET_VALID) != 0
                   && cts.sync_offset != 0) {
                          printf(" (%d.%03dMHz, offset %d", freq / 1000,
                                 freq % 1000, cts.sync_offset);
                  }
                  if ((cts.valid & CCB_TRANS_BUS_WIDTH_VALID) != 0
                   && cts.bus_width > 0) {
                          if ((cts.valid & CCB_TRANS_SYNC_OFFSET_VALID) != 0
                           && cts.sync_offset != 0) {
                                  printf(", ");
                          } else {
                                  printf(" (");
                          }
                          printf("%dbit)", 8 * (0x01 << cts.bus_width));
                  } else if ((cts.valid & CCB_TRANS_SYNC_OFFSET_VALID) != 0
                          && cts.sync_offset != 0) {
                          printf(")");
                  }
  
                  if (path->device->inq_flags & SID_CmdQue
                   || path->device->flags & CAM_DEV_TAG_AFTER_COUNT) {
                          printf(", Tagged Queueing Enabled");
                  }
  
                  printf("\n");
          } else if (path->device->inq_flags & SID_CmdQue
                  || path->device->flags & CAM_DEV_TAG_AFTER_COUNT) {
                  printf("%s%d: Tagged Queueing Enabled\n",
                         periph->periph_name, periph->unit_number);
          }
  
          /*
           * We only want to print the caller's announce string if they've
           * passed one in..
           */
          if (announce_string != NULL)
                  printf("%s%d: %s\n", periph->periph_name,
                         periph->unit_number, announce_string);
          splx(s);
  }
  
  
  static dev_match_ret
  xptbusmatch(struct dev_match_pattern *patterns, int num_patterns,
              struct cam_eb *bus)
  {
          dev_match_ret retval;
          int i;
  
          retval = DM_RET_NONE;
  
          /*
           * If we aren't given something to match against, that's an error.
           */
          if (bus == NULL)
                  return(DM_RET_ERROR);
  
          /*
           * If there are no match entries, then this bus matches no
           * matter what.
           */
          if ((patterns == NULL) || (num_patterns == 0))
                  return(DM_RET_DESCEND | DM_RET_COPY);
  
          for (i = 0; i < num_patterns; i++) {
                  struct bus_match_pattern *cur_pattern;
  
                  /*
                   * If the pattern in question isn't for a bus node, we
                   * aren't interested.  However, we do indicate to the
                   * calling routine that we should continue descending the
                   * tree, since the user wants to match against lower-level
                   * EDT elements.
                   */
                  if (patterns[i].type != DEV_MATCH_BUS) {
                          if ((retval & DM_RET_ACTION_MASK) == DM_RET_NONE)
                                  retval |= DM_RET_DESCEND;
                          continue;
                  }
  
                  cur_pattern = &patterns[i].pattern.bus_pattern;
  
                  /*
                   * If they want to match any bus node, we give them any
                   * device node.
                   */
                  if (cur_pattern->flags == BUS_MATCH_ANY) {
                          /* set the copy flag */
                          retval |= DM_RET_COPY;
  
                          /*
                           * If we've already decided on an action, go ahead
                           * and return.
                           */
                          if ((retval & DM_RET_ACTION_MASK) != DM_RET_NONE)
                                  return(retval);
                  }
  
                  /*
                   * Not sure why someone would do this...
                   */
                  if (cur_pattern->flags == BUS_MATCH_NONE)
                          continue;
  
                  if (((cur_pattern->flags & BUS_MATCH_PATH) != 0)
                   && (cur_pattern->path_id != bus->path_id))
                          continue;
  
                  if (((cur_pattern->flags & BUS_MATCH_BUS_ID) != 0)
                   && (cur_pattern->bus_id != bus->sim->bus_id))
                          continue;
  
                  if (((cur_pattern->flags & BUS_MATCH_UNIT) != 0)
                   && (cur_pattern->unit_number != bus->sim->unit_number))
                          continue;
  
                  if (((cur_pattern->flags & BUS_MATCH_NAME) != 0)
                   && (strncmp(cur_pattern->dev_name, bus->sim->sim_name,
                               DEV_IDLEN) != 0))
                          continue;
  
                  /*
                   * If we get to this point, the user definitely wants 
                   * information on this bus.  So tell the caller to copy the
                   * data out.
                   */
                  retval |= DM_RET_COPY;
  
                  /*
                   * If the return action has been set to descend, then we
                   * know that we've already seen a non-bus matching
                   * expression, therefore we need to further descend the tree.
                   * This won't change by continuing around the loop, so we
                   * go ahead and return.  If we haven't seen a non-bus
                   * matching expression, we keep going around the loop until
                   * we exhaust the matching expressions.  We'll set the stop
                   * flag once we fall out of the loop.
                   */
                  if ((retval & DM_RET_ACTION_MASK) == DM_RET_DESCEND)
                          return(retval);
          }
  
          /*
           * If the return action hasn't been set to descend yet, that means
           * we haven't seen anything other than bus matching patterns.  So
           * tell the caller to stop descending the tree -- the user doesn't
           * want to match against lower level tree elements.
           */
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_NONE)
                  retval |= DM_RET_STOP;
  
          return(retval);
  }
  
  static dev_match_ret
  xptdevicematch(struct dev_match_pattern *patterns, int num_patterns,
                 struct cam_ed *device)
  {
          dev_match_ret retval;
          int i;
  
          retval = DM_RET_NONE;
  
          /*
           * If we aren't given something to match against, that's an error.
           */
          if (device == NULL)
                  return(DM_RET_ERROR);
  
          /*
           * If there are no match entries, then this device matches no
           * matter what.
           */
          if ((patterns == NULL) || (patterns == 0))
                  return(DM_RET_DESCEND | DM_RET_COPY);
  
          for (i = 0; i < num_patterns; i++) {
                  struct device_match_pattern *cur_pattern;
  
                  /*
                   * If the pattern in question isn't for a device node, we
                   * aren't interested.
                   */
                  if (patterns[i].type != DEV_MATCH_DEVICE) {
                          if ((patterns[i].type == DEV_MATCH_PERIPH)
                           && ((retval & DM_RET_ACTION_MASK) == DM_RET_NONE))
                                  retval |= DM_RET_DESCEND;
                          continue;
                  }
  
                  cur_pattern = &patterns[i].pattern.device_pattern;
  
                  /*
                   * If they want to match any device node, we give them any
                   * device node.
                   */
                  if (cur_pattern->flags == DEV_MATCH_ANY) {
                          /* set the copy flag */
                          retval |= DM_RET_COPY;
  
                          
                          /*
                           * If we've already decided on an action, go ahead
                           * and return.
                           */
                          if ((retval & DM_RET_ACTION_MASK) != DM_RET_NONE)
                                  return(retval);
                  }
  
                  /*
                   * Not sure why someone would do this...
                   */
                  if (cur_pattern->flags == DEV_MATCH_NONE)
                          continue;
  
                  if (((cur_pattern->flags & DEV_MATCH_PATH) != 0)
                   && (cur_pattern->path_id != device->target->bus->path_id))
                          continue;
  
                  if (((cur_pattern->flags & DEV_MATCH_TARGET) != 0)
                   && (cur_pattern->target_id != device->target->target_id))
                          continue;
  
                  if (((cur_pattern->flags & DEV_MATCH_LUN) != 0)
                   && (cur_pattern->target_lun != device->lun_id))
                          continue;
  
                  if (((cur_pattern->flags & DEV_MATCH_INQUIRY) != 0)
                   && (cam_quirkmatch((caddr_t)&device->inq_data,
                                      (caddr_t)&cur_pattern->inq_pat,
                                      1, sizeof(cur_pattern->inq_pat),
                                      scsi_static_inquiry_match) == NULL))
                          continue;
  
                  /*
                   * If we get to this point, the user definitely wants 
                   * information on this device.  So tell the caller to copy
                   * the data out.
                   */
                  retval |= DM_RET_COPY;
  
                  /*
                   * If the return action has been set to descend, then we
                   * know that we've already seen a peripheral matching
                   * expression, therefore we need to further descend the tree.
                   * This won't change by continuing around the loop, so we
                   * go ahead and return.  If we haven't seen a peripheral
                   * matching expression, we keep going around the loop until
                   * we exhaust the matching expressions.  We'll set the stop
                   * flag once we fall out of the loop.
                   */
                  if ((retval & DM_RET_ACTION_MASK) == DM_RET_DESCEND)
                          return(retval);
          }
  
          /*
           * If the return action hasn't been set to descend yet, that means
           * we haven't seen any peripheral matching patterns.  So tell the
           * caller to stop descending the tree -- the user doesn't want to
           * match against lower level tree elements.
           */
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_NONE)
                  retval |= DM_RET_STOP;
  
          return(retval);
  }
  
  /*
   * Match a single peripheral against any number of match patterns.
   */
  static dev_match_ret
  xptperiphmatch(struct dev_match_pattern *patterns, int num_patterns,
                 struct cam_periph *periph)
  {
          dev_match_ret retval;
          int i;
  
          /*
           * If we aren't given something to match against, that's an error.
           */
          if (periph == NULL)
                  return(DM_RET_ERROR);
  
          /*
           * If there are no match entries, then this peripheral matches no
           * matter what.
           */
          if ((patterns == NULL) || (num_patterns == 0))
                  return(DM_RET_STOP | DM_RET_COPY);
  
          /*
           * There aren't any nodes below a peripheral node, so there's no
           * reason to descend the tree any further.
           */
          retval = DM_RET_STOP;
  
          for (i = 0; i < num_patterns; i++) {
                  struct periph_match_pattern *cur_pattern;
  
                  /*
                   * If the pattern in question isn't for a peripheral, we
                   * aren't interested.
                   */
                  if (patterns[i].type != DEV_MATCH_PERIPH)
                          continue;
  
                  cur_pattern = &patterns[i].pattern.periph_pattern;
  
                  /*
                   * If they want to match on anything, then we will do so.
                   */
                  if (cur_pattern->flags == PERIPH_MATCH_ANY) {
                          /* set the copy flag */
                          retval |= DM_RET_COPY;
  
                          /*
                           * We've already set the return action to stop,
                           * since there are no nodes below peripherals in
                           * the tree.
                           */
                          return(retval);
                  }
  
                  /*
                   * Not sure why someone would do this...
                   */
                  if (cur_pattern->flags == PERIPH_MATCH_NONE)
                          continue;
  
                  if (((cur_pattern->flags & PERIPH_MATCH_PATH) != 0)
                   && (cur_pattern->path_id != periph->path->bus->path_id))
                          continue;
  
                  /*
                   * For the target and lun id's, we have to make sure the
                   * target and lun pointers aren't NULL.  The xpt peripheral
                   * has a wildcard target and device.
                   */
                  if (((cur_pattern->flags & PERIPH_MATCH_TARGET) != 0)
                   && ((periph->path->target == NULL)
                   ||(cur_pattern->target_id != periph->path->target->target_id)))
                          continue;
  
                  if (((cur_pattern->flags & PERIPH_MATCH_LUN) != 0)
                   && ((periph->path->device == NULL)
                   || (cur_pattern->target_lun != periph->path->device->lun_id)))
                          continue;
  
                  if (((cur_pattern->flags & PERIPH_MATCH_UNIT) != 0)
                   && (cur_pattern->unit_number != periph->unit_number))
                          continue;
  
                  if (((cur_pattern->flags & PERIPH_MATCH_NAME) != 0)
                   && (strncmp(cur_pattern->periph_name, periph->periph_name,
                               DEV_IDLEN) != 0))
                          continue;
  
                  /*
                   * If we get to this point, the user definitely wants 
                   * information on this peripheral.  So tell the caller to
                   * copy the data out.
                   */
                  retval |= DM_RET_COPY;
  
                  /*
                   * The return action has already been set to stop, since
                   * peripherals don't have any nodes below them in the EDT.
                   */
                  return(retval);
          }
  
          /*
           * If we get to this point, the peripheral that was passed in
           * doesn't match any of the patterns.
           */
          return(retval);
  }
  
  static int
  xptedtbusfunc(struct cam_eb *bus, void *arg)
  {
          struct ccb_dev_match *cdm;
          dev_match_ret retval;
  
          cdm = (struct ccb_dev_match *)arg;
  
          /*
           * If our position is for something deeper in the tree, that means
           * that we've already seen this node.  So, we keep going down.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus == bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.cookie.target != NULL))
                  retval = DM_RET_DESCEND;
          else
                  retval = xptbusmatch(cdm->patterns, cdm->num_patterns, bus);
  
          /*
           * If we got an error, bail out of the search.
           */
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_ERROR) {
                  cdm->status = CAM_DEV_MATCH_ERROR;
                  return(0);
          }
  
          /*
           * If the copy flag is set, copy this bus out.
           */
          if (retval & DM_RET_COPY) {
                  int spaceleft, j;
  
                  spaceleft = cdm->match_buf_len - (cdm->num_matches *
                          sizeof(struct dev_match_result));
  
                  /*
                   * If we don't have enough space to put in another
                   * match result, save our position and tell the
                   * user there are more devices to check.
                   */
                  if (spaceleft < sizeof(struct dev_match_result)) {
                          bzero(&cdm->pos, sizeof(cdm->pos));
                          cdm->pos.position_type = 
                                  CAM_DEV_POS_EDT | CAM_DEV_POS_BUS;
  
                          cdm->pos.cookie.bus = bus;
                          cdm->pos.generations[CAM_BUS_GENERATION]=
                                  bus_generation;
                          cdm->status = CAM_DEV_MATCH_MORE;
                          return(0);
                  }
                  j = cdm->num_matches;
                  cdm->num_matches++;
                  cdm->matches[j].type = DEV_MATCH_BUS;
                  cdm->matches[j].result.bus_result.path_id = bus->path_id;
                  cdm->matches[j].result.bus_result.bus_id = bus->sim->bus_id;
                  cdm->matches[j].result.bus_result.unit_number =
                          bus->sim->unit_number;
                  strncpy(cdm->matches[j].result.bus_result.dev_name,
                          bus->sim->sim_name, DEV_IDLEN);
          }
  
          /*
           * If the user is only interested in busses, there's no
           * reason to descend to the next level in the tree.
           */
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_STOP)
                  return(1);
  
          /*
           * If there is a target generation recorded, check it to
           * make sure the target list hasn't changed.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (bus == cdm->pos.cookie.bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.generations[CAM_TARGET_GENERATION] != 0)
           && (cdm->pos.generations[CAM_TARGET_GENERATION] !=
               bus->generation)) {
                  cdm->status = CAM_DEV_MATCH_LIST_CHANGED;
                  return(0);
          }
  
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus == bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.cookie.target != NULL))
                  return(xpttargettraverse(bus,
                                          (struct cam_et *)cdm->pos.cookie.target,
                                           xptedttargetfunc, arg));
          else
                  return(xpttargettraverse(bus, NULL, xptedttargetfunc, arg));
  }
  
  static int
  xptedttargetfunc(struct cam_et *target, void *arg)
  {
          struct ccb_dev_match *cdm;
  
          cdm = (struct ccb_dev_match *)arg;
  
          /*
           * If there is a device list generation recorded, check it to
           * make sure the device list hasn't changed.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus == target->bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.cookie.target == target)
           && (cdm->pos.position_type & CAM_DEV_POS_DEVICE)
           && (cdm->pos.generations[CAM_DEV_GENERATION] != 0)
           && (cdm->pos.generations[CAM_DEV_GENERATION] !=
               target->generation)) {
                  cdm->status = CAM_DEV_MATCH_LIST_CHANGED;
                  return(0);
          }
  
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus == target->bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.cookie.target == target)
           && (cdm->pos.position_type & CAM_DEV_POS_DEVICE)
           && (cdm->pos.cookie.device != NULL))
                  return(xptdevicetraverse(target,
                                          (struct cam_ed *)cdm->pos.cookie.device,
                                           xptedtdevicefunc, arg));
          else
                  return(xptdevicetraverse(target, NULL, xptedtdevicefunc, arg));
  }
  
  static int
  xptedtdevicefunc(struct cam_ed *device, void *arg)
  {
  
          struct ccb_dev_match *cdm;
          dev_match_ret retval;
  
          cdm = (struct ccb_dev_match *)arg;
  
          /*
           * If our position is for something deeper in the tree, that means
           * that we've already seen this node.  So, we keep going down.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_DEVICE)
           && (cdm->pos.cookie.device == device)
           && (cdm->pos.position_type & CAM_DEV_POS_PERIPH)
           && (cdm->pos.cookie.periph != NULL))
                  retval = DM_RET_DESCEND;
          else
                  retval = xptdevicematch(cdm->patterns, cdm->num_patterns,
                                          device);
  
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_ERROR) {
                  cdm->status = CAM_DEV_MATCH_ERROR;
                  return(0);
          }
  
          /*
           * If the copy flag is set, copy this device out.
           */
          if (retval & DM_RET_COPY) {
                  int spaceleft, j;
  
                  spaceleft = cdm->match_buf_len - (cdm->num_matches *
                          sizeof(struct dev_match_result));
  
                  /*
                   * If we don't have enough space to put in another
                   * match result, save our position and tell the
                   * user there are more devices to check.
                   */
                  if (spaceleft < sizeof(struct dev_match_result)) {
                          bzero(&cdm->pos, sizeof(cdm->pos));
                          cdm->pos.position_type = 
                                  CAM_DEV_POS_EDT | CAM_DEV_POS_BUS |
                                  CAM_DEV_POS_TARGET | CAM_DEV_POS_DEVICE;
  
                          cdm->pos.cookie.bus = device->target->bus;
                          cdm->pos.generations[CAM_BUS_GENERATION]=
                                  bus_generation;
                          cdm->pos.cookie.target = device->target;
                          cdm->pos.generations[CAM_TARGET_GENERATION] =
                                  device->target->bus->generation;
                          cdm->pos.cookie.device = device;
                          cdm->pos.generations[CAM_DEV_GENERATION] = 
                                  device->target->generation;
                          cdm->status = CAM_DEV_MATCH_MORE;
                          return(0);
                  }
                  j = cdm->num_matches;
                  cdm->num_matches++;
                  cdm->matches[j].type = DEV_MATCH_DEVICE;
                  cdm->matches[j].result.device_result.path_id =
                          device->target->bus->path_id;
                  cdm->matches[j].result.device_result.target_id =
                          device->target->target_id;
                  cdm->matches[j].result.device_result.target_lun =
                          device->lun_id;
                  bcopy(&device->inq_data,
                        &cdm->matches[j].result.device_result.inq_data,
                        sizeof(struct scsi_inquiry_data));
  
                  /* Let the user know whether this device is unconfigured */
                  if (device->flags & CAM_DEV_UNCONFIGURED)
                          cdm->matches[j].result.device_result.flags =
                                  DEV_RESULT_UNCONFIGURED;
                  else
                          cdm->matches[j].result.device_result.flags =
                                  DEV_RESULT_NOFLAG;
          }
  
          /*
           * If the user isn't interested in peripherals, don't descend
           * the tree any further.
           */
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_STOP)
                  return(1);
  
          /*
           * If there is a peripheral list generation recorded, make sure
           * it hasn't changed.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (device->target->bus == cdm->pos.cookie.bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (device->target == cdm->pos.cookie.target)
           && (cdm->pos.position_type & CAM_DEV_POS_DEVICE)
           && (device == cdm->pos.cookie.device)
           && (cdm->pos.position_type & CAM_DEV_POS_PERIPH)
           && (cdm->pos.generations[CAM_PERIPH_GENERATION] != 0)
           && (cdm->pos.generations[CAM_PERIPH_GENERATION] !=
               device->generation)){
                  cdm->status = CAM_DEV_MATCH_LIST_CHANGED;
                  return(0);
          }
  
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus == device->target->bus)
           && (cdm->pos.position_type & CAM_DEV_POS_TARGET)
           && (cdm->pos.cookie.target == device->target)
           && (cdm->pos.position_type & CAM_DEV_POS_DEVICE)
           && (cdm->pos.cookie.device == device)
           && (cdm->pos.position_type & CAM_DEV_POS_PERIPH)
           && (cdm->pos.cookie.periph != NULL))
                  return(xptperiphtraverse(device,
                                  (struct cam_periph *)cdm->pos.cookie.periph,
                                  xptedtperiphfunc, arg));
          else
                  return(xptperiphtraverse(device, NULL, xptedtperiphfunc, arg));
  }
  
  static int
  xptedtperiphfunc(struct cam_periph *periph, void *arg)
  {
          struct ccb_dev_match *cdm;
          dev_match_ret retval;
  
          cdm = (struct ccb_dev_match *)arg;
  
          retval = xptperiphmatch(cdm->patterns, cdm->num_patterns, periph);
  
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_ERROR) {
                  cdm->status = CAM_DEV_MATCH_ERROR;
                  return(0);
          }
  
          /*
           * If the copy flag is set, copy this peripheral out.
           */
          if (retval & DM_RET_COPY) {
                  int spaceleft, j;
  
                  spaceleft = cdm->match_buf_len - (cdm->num_matches *
                          sizeof(struct dev_match_result));
  
                  /*
                   * If we don't have enough space to put in another
                   * match result, save our position and tell the
                   * user there are more devices to check.
                   */
                  if (spaceleft < sizeof(struct dev_match_result)) {
                          bzero(&cdm->pos, sizeof(cdm->pos));
                          cdm->pos.position_type = 
                                  CAM_DEV_POS_EDT | CAM_DEV_POS_BUS |
                                  CAM_DEV_POS_TARGET | CAM_DEV_POS_DEVICE |
                                  CAM_DEV_POS_PERIPH;
  
                          cdm->pos.cookie.bus = periph->path->bus;
                          cdm->pos.generations[CAM_BUS_GENERATION]=
                                  bus_generation;
                          cdm->pos.cookie.target = periph->path->target;
                          cdm->pos.generations[CAM_TARGET_GENERATION] =
                                  periph->path->bus->generation;
                          cdm->pos.cookie.device = periph->path->device;
                          cdm->pos.generations[CAM_DEV_GENERATION] = 
                                  periph->path->target->generation;
                          cdm->pos.cookie.periph = periph;
                          cdm->pos.generations[CAM_PERIPH_GENERATION] =
                                  periph->path->device->generation;
                          cdm->status = CAM_DEV_MATCH_MORE;
                          return(0);
                  }
  
                  j = cdm->num_matches;
                  cdm->num_matches++;
                  cdm->matches[j].type = DEV_MATCH_PERIPH;
                  cdm->matches[j].result.periph_result.path_id =
                          periph->path->bus->path_id;
                  cdm->matches[j].result.periph_result.target_id =
                          periph->path->target->target_id;
                  cdm->matches[j].result.periph_result.target_lun =
                          periph->path->device->lun_id;
                  cdm->matches[j].result.periph_result.unit_number =
                          periph->unit_number;
                  strncpy(cdm->matches[j].result.periph_result.periph_name,
                          periph->periph_name, DEV_IDLEN);
          }
  
          return(1);
  }
  
  static int
  xptedtmatch(struct ccb_dev_match *cdm)
  {
          int ret;
  
          cdm->num_matches = 0;
  
          /*
           * Check the bus list generation.  If it has changed, the user
           * needs to reset everything and start over.
           */
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.generations[CAM_BUS_GENERATION] != 0)
           && (cdm->pos.generations[CAM_BUS_GENERATION] != bus_generation)) {
                  cdm->status = CAM_DEV_MATCH_LIST_CHANGED;
                  return(0);
          }
  
          if ((cdm->pos.position_type & CAM_DEV_POS_BUS)
           && (cdm->pos.cookie.bus != NULL))
                  ret = xptbustraverse((struct cam_eb *)cdm->pos.cookie.bus,
                                       xptedtbusfunc, cdm);
          else
                  ret = xptbustraverse(NULL, xptedtbusfunc, cdm);
  
          /*
           * If we get back 0, that means that we had to stop before fully
           * traversing the EDT.  It also means that one of the subroutines
           * has set the status field to the proper value.  If we get back 1,
           * we've fully traversed the EDT and copied out any matching entries.
           */
          if (ret == 1)
                  cdm->status = CAM_DEV_MATCH_LAST;
  
          return(ret);
  }
  
  static int
  xptplistpdrvfunc(struct periph_driver **pdrv, void *arg)
  {
          struct ccb_dev_match *cdm;
  
          cdm = (struct ccb_dev_match *)arg;
  
          if ((cdm->pos.position_type & CAM_DEV_POS_PDPTR)
           && (cdm->pos.cookie.pdrv == pdrv)
           && (cdm->pos.position_type & CAM_DEV_POS_PERIPH)
           && (cdm->pos.generations[CAM_PERIPH_GENERATION] != 0)
           && (cdm->pos.generations[CAM_PERIPH_GENERATION] !=
               (*pdrv)->generation)) {
                  cdm->status = CAM_DEV_MATCH_LIST_CHANGED;
                  return(0);
          }
  
          if ((cdm->pos.position_type & CAM_DEV_POS_PDPTR)
           && (cdm->pos.cookie.pdrv == pdrv)
           && (cdm->pos.position_type & CAM_DEV_POS_PERIPH)
           && (cdm->pos.cookie.periph != NULL))
                  return(xptpdperiphtraverse(pdrv,
                                  (struct cam_periph *)cdm->pos.cookie.periph,
                                  xptplistperiphfunc, arg));
          else
                  return(xptpdperiphtraverse(pdrv, NULL,xptplistperiphfunc, arg));
  }
  
  static int
  xptplistperiphfunc(struct cam_periph *periph, void *arg)
  {
          struct ccb_dev_match *cdm;
          dev_match_ret retval;
  
          cdm = (struct ccb_dev_match *)arg;
  
          retval = xptperiphmatch(cdm->patterns, cdm->num_patterns, periph);
  
          if ((retval & DM_RET_ACTION_MASK) == DM_RET_ERROR) {
                  cdm->status = CAM_DEV_MATCH_ERROR;
                  return(0);
          }
  
          /*
           * If the copy flag is set, copy this peripheral out.
           */
          if (retval & DM_RET_COPY) {
                  int spaceleft, j;
  
                  spaceleft = cdm->match_buf_len - (cdm->num_matches *
                          sizeof(struct dev_match_result));
  
                  /*
                   * If we don't have enough space to put in another
                   * match result, save our position and tell the
                   * user there are more devices to check.
                   */
                  if (spaceleft < sizeof(struct dev_match_result)) {
                          struct periph_driver **pdrv;
  
                          pdrv = NULL;
                          bzero(&cdm->pos, sizeof(cdm->pos));
                          cdm->pos.position_type = 
                                  CAM_DEV_POS_PDRV | CAM_DEV_POS_PDPTR |
                                  CAM_DEV_POS_PERIPH;
  
                          /*
                           * This may look a bit non-sensical, but it is
                           * actually quite logical.  There are very few
                           * peripheral drivers, and bloating every peripheral
                           * structure with a pointer back to its parent
                           * peripheral driver linker set entry would cost
                           * more in the long run than doing this quick lookup.
                           */
                          for (pdrv =
                               (struct periph_driver **)periphdriver_set.ls_items;
                               *pdrv != NULL; pdrv++) {
                                  if (strcmp((*pdrv)->driver_name,
                                      periph->periph_name) == 0)
                                          break;
                          }
  
                          if (pdrv == NULL) {
                                  cdm->status = CAM_DEV_MATCH_ERROR;
                                  return(0);
                          }
  
                          cdm->pos.cookie.pdrv = pdrv;
                          /*
                           * The periph generation slot does double duty, as
                           * does the periph pointer slot.  They are used for
                           * both edt and pdrv lookups and positioning.
                           */
                          cdm->pos.cookie.periph = periph;
                          cdm->pos.generations[CAM_PERIPH_GENERATION] =
                                  (*pdrv)->generation;
                          cdm->status = CAM_DEV_MATCH_MORE;
                          return(0);
                  }
  
                  j = cdm->num_matches;
                  cdm->num_matches++;
                  cdm->matches[j].type = DEV_MATCH_PERIPH;
                  cdm->matches[j].result.periph_result.path_id =
                          periph->path->bus->path_id;
  
                  /*
                   * The transport layer peripheral doesn't have a target or
                   * lun.
                   */
                  if (periph->path->target)
                          cdm->matches[j].result.periph_result.target_id =
                                  periph->path->target->target_id;
                  else
                          cdm->matches[j].result.periph_result.target_id = -1;
  
                  if (periph->path->device)
                          cdm->matches[j].result.periph_result.target_lun =
                                  periph->path->device->lun_id;
                  else
                          cdm->matches[j].result.periph_result.target_lun = -1;
  
                  cdm->matches[j].result.periph_result.unit_number =
                          periph->unit_number;
                  strncpy(cdm->matches[j].result.periph_result.periph_name,
                          periph->periph_name, DEV_IDLEN);
          }
  
          return(1);
  }
  
  static int
  xptperiphlistmatch(struct ccb_dev_match *cdm)
  {
          int ret;
  
          cdm->num_matches = 0;
  
          /*
           * At this point in the edt traversal function, we check the bus
           * list generation to make sure that no busses have been added or
           * removed since the user last sent a XPT_DEV_MATCH ccb through.
           * For the peripheral driver list traversal function, however, we
           * don't have to worry about new peripheral driver types coming or
           * going; they're in a linker set, and therefore can't change
           * without a recompile.
           */
  
          if ((cdm->pos.position_type & CAM_DEV_POS_PDPTR)
           && (cdm->pos.cookie.pdrv != NULL))
                  ret = xptpdrvtraverse(
                                  (struct periph_driver **)cdm->pos.cookie.pdrv,
                                  xptplistpdrvfunc, cdm);
          else
                  ret = xptpdrvtraverse(NULL, xptplistpdrvfunc, cdm);
  
          /*
           * If we get back 0, that means that we had to stop before fully
           * traversing the peripheral driver tree.  It also means that one of
           * the subroutines has set the status field to the proper value.  If
           * we get back 1, we've fully traversed the EDT and copied out any
           * matching entries.
           */
          if (ret == 1)
                  cdm->status = CAM_DEV_MATCH_LAST;
  
          return(ret);
  }
  
  static int
  xptbustraverse(struct cam_eb *start_bus, xpt_busfunc_t *tr_func, void *arg)
  {
          struct cam_eb *bus, *next_bus;
          int retval;
  
          retval = 1;
  
          for (bus = (start_bus ? start_bus : TAILQ_FIRST(&xpt_busses));
               bus != NULL;
               bus = next_bus) {
                  next_bus = TAILQ_NEXT(bus, links);
  
                  retval = tr_func(bus, arg);
                  if (retval == 0)
                          return(retval);
          }
  
          return(retval);
  }
  
  static int
  xpttargettraverse(struct cam_eb *bus, struct cam_et *start_target,
                    xpt_targetfunc_t *tr_func, void *arg)
  {
          struct cam_et *target, *next_target;
          int retval;
  
          retval = 1;
          for (target = (start_target ? start_target :
                         TAILQ_FIRST(&bus->et_entries));
               target != NULL; target = next_target) {
  
                  next_target = TAILQ_NEXT(target, links);
  
                  retval = tr_func(target, arg);
  
                  if (retval == 0)
                          return(retval);
          }
  
          return(retval);
  }
  
  static int
  xptdevicetraverse(struct cam_et *target, struct cam_ed *start_device,
                    xpt_devicefunc_t *tr_func, void *arg)
  {
          struct cam_ed *device, *next_device;
          int retval;
  
          retval = 1;
          for (device = (start_device ? start_device :
                         TAILQ_FIRST(&target->ed_entries));
               device != NULL;
               device = next_device) {
  
                  next_device = TAILQ_NEXT(device, links);
  
                  retval = tr_func(device, arg);
  
                  if (retval == 0)
                          return(retval);
          }
  
          return(retval);
  }
  
  static int
  xptperiphtraverse(struct cam_ed *device, struct cam_periph *start_periph,
                    xpt_periphfunc_t *tr_func, void *arg)
  {
          struct cam_periph *periph, *next_periph;
          int retval;
  
          retval = 1;
  
          for (periph = (start_periph ? start_periph :
                         SLIST_FIRST(&device->periphs));
               periph != NULL;
               periph = next_periph) {
  
                  next_periph = SLIST_NEXT(periph, periph_links);
  
                  retval = tr_func(periph, arg);
                  if (retval == 0)
                          return(retval);
          }
  
          return(retval);
  }
  
  static int
  xptpdrvtraverse(struct periph_driver **start_pdrv,
                  xpt_pdrvfunc_t *tr_func, void *arg)
  {
          struct periph_driver **pdrv;
          int retval;
  
          retval = 1;
  
          /*
           * We don't traverse the peripheral driver list like we do the
           * other lists, because it is a linker set, and therefore cannot be
           * changed during runtime.  If the peripheral driver list is ever
           * re-done to be something other than a linker set (i.e. it can
           * change while the system is running), the list traversal should
           * be modified to work like the other traversal functions.
           */
          for (pdrv = (start_pdrv ? start_pdrv :
               (struct periph_driver **)periphdriver_set.ls_items);
               *pdrv != NULL; pdrv++) {
                  retval = tr_func(pdrv, arg);
  
                  if (retval == 0)
                          return(retval);
          }
  
          return(retval);
  }
  
  static int
  xptpdperiphtraverse(struct periph_driver **pdrv,
                      struct cam_periph *start_periph,
                      xpt_periphfunc_t *tr_func, void *arg)
  {
          struct cam_periph *periph, *next_periph;
          int retval;
  
          retval = 1;
  
          for (periph = (start_periph ? start_periph :
               TAILQ_FIRST(&(*pdrv)->units)); periph != NULL;
               periph = next_periph) {
  
                  next_periph = TAILQ_NEXT(periph, unit_links);
  
                  retval = tr_func(periph, arg);
                  if (retval == 0)
                          return(retval);
          }
          return(retval);
  }
  
  static int
  xptdefbusfunc(struct cam_eb *bus, void *arg)
  {
          struct xpt_traverse_config *tr_config;
  
          tr_config = (struct xpt_traverse_config *)arg;
  
          if (tr_config->depth == XPT_DEPTH_BUS) {
                  xpt_busfunc_t *tr_func;
  
                  tr_func = (xpt_busfunc_t *)tr_config->tr_func;
  
                  return(tr_func(bus, tr_config->tr_arg));
          } else
                  return(xpttargettraverse(bus, NULL, xptdeftargetfunc, arg));
  }
  
  static int
  xptdeftargetfunc(struct cam_et *target, void *arg)
  {
          struct xpt_traverse_config *tr_config;
  
          tr_config = (struct xpt_traverse_config *)arg;
  
          if (tr_config->depth == XPT_DEPTH_TARGET) {
                  xpt_targetfunc_t *tr_func;
  
                  tr_func = (xpt_targetfunc_t *)tr_config->tr_func;
  
                  return(tr_func(target, tr_config->tr_arg));
          } else
                  return(xptdevicetraverse(target, NULL, xptdefdevicefunc, arg));
  }
  
  static int
  xptdefdevicefunc(struct cam_ed *device, void *arg)
  {
          struct xpt_traverse_config *tr_config;
  
          tr_config = (struct xpt_traverse_config *)arg;
  
          if (tr_config->depth == XPT_DEPTH_DEVICE) {
                  xpt_devicefunc_t *tr_func;
  
                  tr_func = (xpt_devicefunc_t *)tr_config->tr_func;
  
                  return(tr_func(device, tr_config->tr_arg));
          } else
                  return(xptperiphtraverse(device, NULL, xptdefperiphfunc, arg));
  }
  
  static int
  xptdefperiphfunc(struct cam_periph *periph, void *arg)
  {
          struct xpt_traverse_config *tr_config;
          xpt_periphfunc_t *tr_func;
  
          tr_config = (struct xpt_traverse_config *)arg;
  
          tr_func = (xpt_periphfunc_t *)tr_config->tr_func;
  
          /*
           * Unlike the other default functions, we don't check for depth
           * here.  The peripheral driver level is the last level in the EDT,
           * so if we're here, we should execute the function in question.
           */
          return(tr_func(periph, tr_config->tr_arg));
  }
  
  /*
   * Execute the given function for every bus in the EDT.
   */
  static int
  xpt_for_all_busses(xpt_busfunc_t *tr_func, void *arg)
  {
          struct xpt_traverse_config tr_config;
  
          tr_config.depth = XPT_DEPTH_BUS;
          tr_config.tr_func = tr_func;
          tr_config.tr_arg = arg;
  
          return(xptbustraverse(NULL, xptdefbusfunc, &tr_config));
  }
  
  #ifdef notusedyet
  /*
   * Execute the given function for every target in the EDT.
   */
  static int
  xpt_for_all_targets(xpt_targetfunc_t *tr_func, void *arg)
  {
          struct xpt_traverse_config tr_config;
  
          tr_config.depth = XPT_DEPTH_TARGET;
          tr_config.tr_func = tr_func;
          tr_config.tr_arg = arg;
  
          return(xptbustraverse(NULL, xptdefbusfunc, &tr_config));
  }
  #endif /* notusedyet */
  
  /*
   * Execute the given function for every device in the EDT.
   */
  static int
  xpt_for_all_devices(xpt_devicefunc_t *tr_func, void *arg)
  {
          struct xpt_traverse_config tr_config;
  
          tr_config.depth = XPT_DEPTH_DEVICE;
          tr_config.tr_func = tr_func;
          tr_config.tr_arg = arg;
  
          return(xptbustraverse(NULL, xptdefbusfunc, &tr_config));
  }
  
  #ifdef notusedyet
  /*
   * Execute the given function for every peripheral in the EDT.
   */
  static int
  xpt_for_all_periphs(xpt_periphfunc_t *tr_func, void *arg)
  {
          struct xpt_traverse_config tr_config;
  
          tr_config.depth = XPT_DEPTH_PERIPH;
          tr_config.tr_func = tr_func;
          tr_config.tr_arg = arg;
  
          return(xptbustraverse(NULL, xptdefbusfunc, &tr_config));
  }
  #endif /* notusedyet */
  
  static int
  xptsetasyncfunc(struct cam_ed *device, void *arg)
  {
          struct cam_path path;
          struct ccb_getdev cgd;
          struct async_node *cur_entry;
  
          cur_entry = (struct async_node *)arg;
  
          /*
           * Don't report unconfigured devices (Wildcard devs,
           * devices only for target mode, device instances
           * that have been invalidated but are waiting for
           * their last reference count to be released).
           */
          if ((device->flags & CAM_DEV_UNCONFIGURED) != 0)
                  return (1);
  
          xpt_compile_path(&path,
                           NULL,
                           device->target->bus->path_id,
                           device->target->target_id,
                           device->lun_id);
          xpt_setup_ccb(&cgd.ccb_h, &path, /*priority*/1);
          cgd.ccb_h.func_code = XPT_GDEV_TYPE;
          xpt_action((union ccb *)&cgd);
          cur_entry->callback(cur_entry->callback_arg,
                              AC_FOUND_DEVICE,
                              &path, &cgd);
          xpt_release_path(&path);
  
          return(1);
  }
  
  static int
  xptsetasyncbusfunc(struct cam_eb *bus, void *arg)
  {
          struct cam_path path;
          struct ccb_pathinq cpi;
          struct async_node *cur_entry;
  
          cur_entry = (struct async_node *)arg;
  
          xpt_compile_path(&path, /*periph*/NULL,
                           bus->sim->path_id,
                           CAM_TARGET_WILDCARD,
                           CAM_LUN_WILDCARD);
          xpt_setup_ccb(&cpi.ccb_h, &path, /*priority*/1);
          cpi.ccb_h.func_code = XPT_PATH_INQ;
          xpt_action((union ccb *)&cpi);
          cur_entry->callback(cur_entry->callback_arg,
                              AC_PATH_REGISTERED,
                              &path, &cpi);
          xpt_release_path(&path);
  
          return(1);
  }
  
  void
  xpt_action(union ccb *start_ccb)
  {
          int iopl;
  
          CAM_DEBUG(start_ccb->ccb_h.path, CAM_DEBUG_TRACE, ("xpt_action\n"));
  
          start_ccb->ccb_h.status = CAM_REQ_INPROG;
  
          iopl = splsoftcam();
          switch (start_ccb->ccb_h.func_code) {
          case XPT_SCSI_IO:
          {
  #ifdef CAMDEBUG
                  char cdb_str[(SCSI_MAX_CDBLEN * 3) + 1];
                  struct cam_path *path;
  
                  path = start_ccb->ccb_h.path;
  #endif
  
                  /*
                   * For the sake of compatibility with SCSI-1
                   * devices that may not understand the identify
                   * message, we include lun information in the
                   * second byte of all commands.  SCSI-1 specifies
                   * that luns are a 3 bit value and reserves only 3
                   * bits for lun information in the CDB.  Later
                   * revisions of the SCSI spec allow for more than 8
                   * luns, but have deprecated lun information in the
                   * CDB.  So, if the lun won't fit, we must omit.
                   *
                   * Also be aware that during initial probing for devices,
                   * the inquiry information is unknown but initialized to 0.
                   * This means that this code will be exercised while probing
                   * devices with an ANSI revision greater than 2.
                   */
                  if (SID_ANSI_REV(&start_ccb->ccb_h.path->device->inq_data) <= 2
                   && start_ccb->ccb_h.target_lun < 8
                   && (start_ccb->ccb_h.flags & CAM_CDB_POINTER) == 0) {
  
                          start_ccb->csio.cdb_io.cdb_bytes[1] |=
                              start_ccb->ccb_h.target_lun << 5;
                  }
                  start_ccb->csio.scsi_status = SCSI_STATUS_OK;
                  CAM_DEBUG(path, CAM_DEBUG_CDB,("%s. CDB: %s\n",
                            scsi_op_desc(start_ccb->csio.cdb_io.cdb_bytes[0],
                                         &path->device->inq_data),
                            scsi_cdb_string(start_ccb->csio.cdb_io.cdb_bytes,
                                            cdb_str, sizeof(cdb_str))));
                  /* FALLTHROUGH */
          }
          case XPT_TARGET_IO:
          case XPT_CONT_TARGET_IO:
                  start_ccb->csio.sense_resid = 0;
                  start_ccb->csio.resid = 0;
                  /* FALLTHROUGH */
          case XPT_RESET_DEV:
          case XPT_ENG_EXEC:
          {
                  struct cam_path *path;
                  int s;
                  int runq;
  
                  path = start_ccb->ccb_h.path;
                  s = splsoftcam();
  
                  cam_ccbq_insert_ccb(&path->device->ccbq, start_ccb);
                  if (path->device->qfrozen_cnt == 0)
                          runq = xpt_schedule_dev_sendq(path->bus, path->device);
                  else
                          runq = 0;
                  splx(s);
                  if (runq != 0)
                          xpt_run_dev_sendq(path->bus);
                  break;
          }
          case XPT_SET_TRAN_SETTINGS:
          {
                  xpt_set_transfer_settings(&start_ccb->cts,
                                            start_ccb->ccb_h.path->device,
                                            /*async_update*/FALSE);
                  break;
          }
          case XPT_CALC_GEOMETRY:
          {
                  struct cam_sim *sim;
  
                  /* Filter out garbage */
                  if (start_ccb->ccg.block_size == 0
                   || start_ccb->ccg.volume_size == 0) {
                          start_ccb->ccg.cylinders = 0;
                          start_ccb->ccg.heads = 0;
                          start_ccb->ccg.secs_per_track = 0;
                          start_ccb->ccb_h.status = CAM_REQ_CMP;
                          break;
                  }
  #ifdef PC98
                  /*
                   * In a PC-98 system, geometry translation depens on
                   * the "real" device geometry obtained from mode page 4.
                   * SCSI geometry translation is performed in the
                   * initialization routine of the SCSI BIOS and the result
                   * stored in host memory.  If the translation is available
                   * in host memory, use it.  If not, rely on the default
                   * translation the device driver performs.
                   */
                  if (scsi_da_bios_params(&start_ccb->ccg) != 0) {
                          start_ccb->ccb_h.status = CAM_REQ_CMP;
                          break;
                  }
  #endif
                  sim = start_ccb->ccb_h.path->bus->sim;
                  (*(sim->sim_action))(sim, start_ccb);
                  break;
          }
          case XPT_ABORT:
          {
                  union ccb* abort_ccb;
                  int s;                          
  
                  abort_ccb = start_ccb->cab.abort_ccb;
                  if (XPT_FC_IS_DEV_QUEUED(abort_ccb)) {
  
                          if (abort_ccb->ccb_h.pinfo.index >= 0) {
                                  struct cam_ccbq *ccbq;
  
                                  ccbq = &abort_ccb->ccb_h.path->device->ccbq;
                                  cam_ccbq_remove_ccb(ccbq, abort_ccb);
                                  abort_ccb->ccb_h.status =
                                      CAM_REQ_ABORTED|CAM_DEV_QFRZN;
                                  xpt_freeze_devq(abort_ccb->ccb_h.path, 1);
                                  s = splcam();
                                  xpt_done(abort_ccb);
                                  splx(s);
                                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                                  break;
                          }
                          if (abort_ccb->ccb_h.pinfo.index == CAM_UNQUEUED_INDEX
                           && (abort_ccb->ccb_h.status & CAM_SIM_QUEUED) == 0) {
                                  /*
                                   * We've caught this ccb en route to
                                   * the SIM.  Flag it for abort and the
                                   * SIM will do so just before starting
                                   * real work on the CCB.
                                   */
                                  abort_ccb->ccb_h.status =
                                      CAM_REQ_ABORTED|CAM_DEV_QFRZN;
                                  xpt_freeze_devq(abort_ccb->ccb_h.path, 1);
                                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                                  break;
                          }
                  } 
                  if (XPT_FC_IS_QUEUED(abort_ccb)
                   && (abort_ccb->ccb_h.pinfo.index == CAM_DONEQ_INDEX)) {
                          /*
                           * It's already completed but waiting
                           * for our SWI to get to it.
                           */
                          start_ccb->ccb_h.status = CAM_UA_ABORT;
                          break;
                  }
                  /*
                   * If we weren't able to take care of the abort request
                   * in the XPT, pass the request down to the SIM for processing.
                   */
                  /* FALLTHROUGH */
          }
          case XPT_ACCEPT_TARGET_IO:
          case XPT_EN_LUN:
          case XPT_IMMED_NOTIFY:
          case XPT_NOTIFY_ACK:
          case XPT_GET_TRAN_SETTINGS:
          case XPT_RESET_BUS:
          {
                  struct cam_sim *sim;
  
                  sim = start_ccb->ccb_h.path->bus->sim;
                  (*(sim->sim_action))(sim, start_ccb);
                  break;
          }
          case XPT_PATH_INQ:
          {
                  struct cam_sim *sim;
  
                  sim = start_ccb->ccb_h.path->bus->sim;
                  (*(sim->sim_action))(sim, start_ccb);
                  break;
          }
          case XPT_PATH_STATS:
                  start_ccb->cpis.last_reset =
                          start_ccb->ccb_h.path->bus->last_reset;
                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                  break;
          case XPT_GDEV_TYPE:
          {
                  struct cam_ed *dev;
                  int s;
  
                  dev = start_ccb->ccb_h.path->device;
                  s = splcam();
                  if ((dev->flags & CAM_DEV_UNCONFIGURED) != 0) {
                          start_ccb->ccb_h.status = CAM_DEV_NOT_THERE;
                  } else {
                          struct ccb_getdev *cgd;
                          struct cam_eb *bus;
                          struct cam_et *tar;
  
                          cgd = &start_ccb->cgd;
                          bus = cgd->ccb_h.path->bus;
                          tar = cgd->ccb_h.path->target;
                          cgd->inq_data = dev->inq_data;
                          cgd->ccb_h.status = CAM_REQ_CMP;
                          cgd->serial_num_len = dev->serial_num_len;
                          if ((dev->serial_num_len > 0)
                           && (dev->serial_num != NULL))
                                  bcopy(dev->serial_num, cgd->serial_num,
                                        dev->serial_num_len);
                  }
                  splx(s);
                  break; 
          }
          case XPT_GDEV_STATS:
          {
                  struct cam_ed *dev;
                  int s;
  
                  dev = start_ccb->ccb_h.path->device;
                  s = splcam();
                  if ((dev->flags & CAM_DEV_UNCONFIGURED) != 0) {
                          start_ccb->ccb_h.status = CAM_DEV_NOT_THERE;
                  } else {
                          struct ccb_getdevstats *cgds;
                          struct cam_eb *bus;
                          struct cam_et *tar;
  
                          cgds = &start_ccb->cgds;
                          bus = cgds->ccb_h.path->bus;
                          tar = cgds->ccb_h.path->target;
                          cgds->dev_openings = dev->ccbq.dev_openings;
                          cgds->dev_active = dev->ccbq.dev_active;
                          cgds->devq_openings = dev->ccbq.devq_openings;
                          cgds->devq_queued = dev->ccbq.queue.entries;
                          cgds->held = dev->ccbq.held;
                          cgds->last_reset = tar->last_reset;
                          cgds->maxtags = dev->quirk->maxtags;
                          cgds->mintags = dev->quirk->mintags;
                          if (timevalcmp(&tar->last_reset, &bus->last_reset, <))
                                  cgds->last_reset = bus->last_reset;
                          cgds->ccb_h.status = CAM_REQ_CMP;
                  }
                  splx(s);
                  break;
          }
          case XPT_GDEVLIST:
          {
                  struct cam_periph       *nperiph;
                  struct periph_list      *periph_head;
                  struct ccb_getdevlist   *cgdl;
                  int                     i;
                  int                     s;
                  struct cam_ed           *device;
                  int                     found;
  
  
                  found = 0;
  
                  /*
                   * Don't want anyone mucking with our data.
                   */
                  s = splcam();
                  device = start_ccb->ccb_h.path->device;
                  periph_head = &device->periphs;
                  cgdl = &start_ccb->cgdl;
  
                  /*
                   * Check and see if the list has changed since the user
                   * last requested a list member.  If so, tell them that the
                   * list has changed, and therefore they need to start over 
                   * from the beginning.
                   */
                  if ((cgdl->index != 0) && 
                      (cgdl->generation != device->generation)) {
                          cgdl->status = CAM_GDEVLIST_LIST_CHANGED;
                          splx(s);
                          break;
                  }
  
                  /*
                   * Traverse the list of peripherals and attempt to find 
                   * the requested peripheral.
                   */
                  for (nperiph = periph_head->slh_first, i = 0;
                       (nperiph != NULL) && (i <= cgdl->index);
                       nperiph = nperiph->periph_links.sle_next, i++) {
                          if (i == cgdl->index) {
                                  strncpy(cgdl->periph_name,
                                          nperiph->periph_name,
                                          DEV_IDLEN);
                                  cgdl->unit_number = nperiph->unit_number;
                                  found = 1;
                          }
                  }
                  if (found == 0) {
                          cgdl->status = CAM_GDEVLIST_ERROR;
                          splx(s);
                          break;
                  }
  
                  if (nperiph == NULL)
                          cgdl->status = CAM_GDEVLIST_LAST_DEVICE;
                  else
                          cgdl->status = CAM_GDEVLIST_MORE_DEVS;
  
                  cgdl->index++;
                  cgdl->generation = device->generation;
  
                  splx(s);
                  cgdl->ccb_h.status = CAM_REQ_CMP;
                  break;
          }
          case XPT_DEV_MATCH:
          {
                  int s;
                  dev_pos_type position_type;
                  struct ccb_dev_match *cdm;
                  int ret;
  
                  cdm = &start_ccb->cdm;
  
                  /*
                   * Prevent EDT changes while we traverse it.
                   */
                  s = splcam();
                  /*
                   * There are two ways of getting at information in the EDT.
                   * The first way is via the primary EDT tree.  It starts
                   * with a list of busses, then a list of targets on a bus,
                   * then devices/luns on a target, and then peripherals on a
                   * device/lun.  The "other" way is by the peripheral driver
                   * lists.  The peripheral driver lists are organized by
                   * peripheral driver.  (obviously)  So it makes sense to
                   * use the peripheral driver list if the user is looking
                   * for something like "da1", or all "da" devices.  If the
                   * user is looking for something on a particular bus/target
                   * or lun, it's generally better to go through the EDT tree.
                   */
  
                  if (cdm->pos.position_type != CAM_DEV_POS_NONE)
                          position_type = cdm->pos.position_type;
                  else {
                          int i;
  
                          position_type = CAM_DEV_POS_NONE;
  
                          for (i = 0; i < cdm->num_patterns; i++) {
                                  if ((cdm->patterns[i].type == DEV_MATCH_BUS)
                                   ||(cdm->patterns[i].type == DEV_MATCH_DEVICE)){
                                          position_type = CAM_DEV_POS_EDT;
                                          break;
                                  }
                          }
  
                          if (cdm->num_patterns == 0)
                                  position_type = CAM_DEV_POS_EDT;
                          else if (position_type == CAM_DEV_POS_NONE)
                                  position_type = CAM_DEV_POS_PDRV;
                  }
  
                  switch(position_type & CAM_DEV_POS_TYPEMASK) {
                  case CAM_DEV_POS_EDT:
                          ret = xptedtmatch(cdm);
                          break;
                  case CAM_DEV_POS_PDRV:
                          ret = xptperiphlistmatch(cdm);
                          break;
                  default:
                          cdm->status = CAM_DEV_MATCH_ERROR;
                          break;
                  }
  
                  splx(s);
  
                  if (cdm->status == CAM_DEV_MATCH_ERROR)
                          start_ccb->ccb_h.status = CAM_REQ_CMP_ERR;
                  else
                          start_ccb->ccb_h.status = CAM_REQ_CMP;
  
                  break;
          }
          case XPT_SASYNC_CB:
          {
                  struct ccb_setasync *csa;
                  struct async_node *cur_entry;
                  struct async_list *async_head;
                  u_int32_t added;
                  int s;
  
                  csa = &start_ccb->csa;
                  added = csa->event_enable;
                  async_head = &csa->ccb_h.path->device->asyncs;
  
                  /*
                   * If there is already an entry for us, simply
                   * update it.
                   */
                  s = splcam();
                  cur_entry = SLIST_FIRST(async_head);
                  while (cur_entry != NULL) {
                          if ((cur_entry->callback_arg == csa->callback_arg)
                           && (cur_entry->callback == csa->callback))
                                  break;
                          cur_entry = SLIST_NEXT(cur_entry, links);
                  }
  
                  if (cur_entry != NULL) {
                          /*
                           * If the request has no flags set,
                           * remove the entry.
                           */
                          added &= ~cur_entry->event_enable;
                          if (csa->event_enable == 0) {
                                  SLIST_REMOVE(async_head, cur_entry,
                                               async_node, links);
                                  csa->ccb_h.path->device->refcount--;
                                  free(cur_entry, M_DEVBUF);
                          } else {
                                  cur_entry->event_enable = csa->event_enable;
                          }
                  } else {
                          cur_entry = malloc(sizeof(*cur_entry), M_DEVBUF,
                                             M_NOWAIT);
                          if (cur_entry == NULL) {
                                  splx(s);
                                  csa->ccb_h.status = CAM_RESRC_UNAVAIL;
                                  break;
                          }
                          cur_entry->event_enable = csa->event_enable;
                          cur_entry->callback_arg = csa->callback_arg;
                          cur_entry->callback = csa->callback;
                          SLIST_INSERT_HEAD(async_head, cur_entry, links);
                          csa->ccb_h.path->device->refcount++;
                  }
  
                  if ((added & AC_FOUND_DEVICE) != 0) {
                          /*
                           * Get this peripheral up to date with all
                           * the currently existing devices.
                           */
                          xpt_for_all_devices(xptsetasyncfunc, cur_entry);
                  }
                  if ((added & AC_PATH_REGISTERED) != 0) {
                          /*
                           * Get this peripheral up to date with all
                           * the currently existing busses.
                           */
                          xpt_for_all_busses(xptsetasyncbusfunc, cur_entry);
                  }
                  splx(s);
                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                  break;
          }
          case XPT_REL_SIMQ:
          {
                  struct ccb_relsim *crs;
                  struct cam_ed *dev;
                  int s;
  
                  crs = &start_ccb->crs;
                  dev = crs->ccb_h.path->device;
                  if (dev == NULL) {
  
                          crs->ccb_h.status = CAM_DEV_NOT_THERE;
                          break;
                  }
  
                  s = splcam();
  
                  if ((crs->release_flags & RELSIM_ADJUST_OPENINGS) != 0) {
  
                          if ((dev->inq_data.flags & SID_CmdQue) != 0) {
  
                                  /* Don't ever go below one opening */
                                  if (crs->openings > 0) {
                                          xpt_dev_ccbq_resize(crs->ccb_h.path,
                                                              crs->openings);
  
                                          if (bootverbose) {
                                                  xpt_print_path(crs->ccb_h.path);
                                                  printf("tagged openings "
                                                         "now %d\n",
                                                         crs->openings);
                                          }
                                  }
                          }
                  }
  
                  if ((crs->release_flags & RELSIM_RELEASE_AFTER_TIMEOUT) != 0) {
  
                          if ((dev->flags & CAM_DEV_REL_TIMEOUT_PENDING) != 0) {
  
                                  /*
                                   * Just extend the old timeout and decrement
                                   * the freeze count so that a single timeout
                                   * is sufficient for releasing the queue.
                                   */
                                  start_ccb->ccb_h.flags &= ~CAM_DEV_QFREEZE;
                                  untimeout(xpt_release_devq_timeout,
                                            dev, dev->c_handle);
                          } else {
  
                                  start_ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
                          }
  
                          dev->c_handle =
                                  timeout(xpt_release_devq_timeout,
                                          dev,
                                          (crs->release_timeout * hz) / 1000);
  
                          dev->flags |= CAM_DEV_REL_TIMEOUT_PENDING;
  
                  }
  
                  if ((crs->release_flags & RELSIM_RELEASE_AFTER_CMDCMPLT) != 0) {
  
                          if ((dev->flags & CAM_DEV_REL_ON_COMPLETE) != 0) {
                                  /*
                                   * Decrement the freeze count so that a single
                                   * completion is still sufficient to unfreeze
                                   * the queue.
                                   */
                                  start_ccb->ccb_h.flags &= ~CAM_DEV_QFREEZE;
                          } else {
                                  
                                  dev->flags |= CAM_DEV_REL_ON_COMPLETE;
                                  start_ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
                          }
                  }
  
                  if ((crs->release_flags & RELSIM_RELEASE_AFTER_QEMPTY) != 0) {
  
                          if ((dev->flags & CAM_DEV_REL_ON_QUEUE_EMPTY) != 0
                           || (dev->ccbq.dev_active == 0)) {
  
                                  start_ccb->ccb_h.flags &= ~CAM_DEV_QFREEZE;
                          } else {
                                  
                                  dev->flags |= CAM_DEV_REL_ON_QUEUE_EMPTY;
                                  start_ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
                          }
                  }
                  splx(s);
                  
                  if ((start_ccb->ccb_h.flags & CAM_DEV_QFREEZE) == 0) {
  
                          xpt_release_devq(crs->ccb_h.path, /*count*/1,
                                           /*run_queue*/TRUE);
                  }
                  start_ccb->crs.qfrozen_cnt = dev->qfrozen_cnt;
                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                  break;
          }
          case XPT_SCAN_BUS:
                  xpt_scan_bus(start_ccb->ccb_h.path->periph, start_ccb);
                  break;
          case XPT_SCAN_LUN:
                  xpt_scan_lun(start_ccb->ccb_h.path->periph,
                               start_ccb->ccb_h.path, start_ccb->crcn.flags,
                               start_ccb);
                  break;
          case XPT_DEBUG: {
  #ifdef CAMDEBUG
                  int s;
                  
                  s = splcam();
  #ifdef CAM_DEBUG_DELAY
                  cam_debug_delay = CAM_DEBUG_DELAY;
  #endif
                  cam_dflags = start_ccb->cdbg.flags;
                  if (cam_dpath != NULL) {
                          xpt_free_path(cam_dpath);
                          cam_dpath = NULL;
                  }
  
                  if (cam_dflags != CAM_DEBUG_NONE) {
                          if (xpt_create_path(&cam_dpath, xpt_periph,
                                              start_ccb->ccb_h.path_id,
                                              start_ccb->ccb_h.target_id,
                                              start_ccb->ccb_h.target_lun) !=
                                              CAM_REQ_CMP) {
                                  start_ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
                                  cam_dflags = CAM_DEBUG_NONE;
                          } else {
                                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                                  xpt_print_path(cam_dpath);
                                  printf("debugging flags now %x\n", cam_dflags);
                          }
                  } else {
                          cam_dpath = NULL;
                          start_ccb->ccb_h.status = CAM_REQ_CMP;
                  }
                  splx(s);
  #else /* !CAMDEBUG */
                  start_ccb->ccb_h.status = CAM_FUNC_NOTAVAIL;
  #endif /* CAMDEBUG */
                  break;
          }
          case XPT_NOOP:
                  if ((start_ccb->ccb_h.flags & CAM_DEV_QFREEZE) != 0)
                          xpt_freeze_devq(start_ccb->ccb_h.path, 1);
                  start_ccb->ccb_h.status = CAM_REQ_CMP;
                  break;
          default:
          case XPT_SDEV_TYPE:
          case XPT_TERM_IO:
          case XPT_ENG_INQ:
                  /* XXX Implement */
                  start_ccb->ccb_h.status = CAM_PROVIDE_FAIL;
                  break;
          }
          splx(iopl);
  }
  
  void
  xpt_polled_action(union ccb *start_ccb)
  {
          int       s;
          u_int32_t timeout;
          struct    cam_sim *sim; 
          struct    cam_devq *devq;
          struct    cam_ed *dev;
  
          timeout = start_ccb->ccb_h.timeout;
          sim = start_ccb->ccb_h.path->bus->sim;
          devq = sim->devq;
          dev = start_ccb->ccb_h.path->device;
  
          s = splcam();
  
          /*
           * Steal an opening so that no other queued requests
           * can get it before us while we simulate interrupts.
           */
          dev->ccbq.devq_openings--;
          dev->ccbq.dev_openings--;       
          
          while((devq->send_openings <= 0 || dev->ccbq.dev_openings < 0)
             && (--timeout > 0)) {
                  DELAY(1000);
                  (*(sim->sim_poll))(sim);
                  swi_camnet();
                  swi_cambio();           
          }
          
          dev->ccbq.devq_openings++;
          dev->ccbq.dev_openings++;
          
          if (timeout != 0) {
                  xpt_action(start_ccb);
                  while(--timeout > 0) {
                          (*(sim->sim_poll))(sim);
                          swi_camnet();
                          swi_cambio();
                          if ((start_ccb->ccb_h.status  & CAM_STATUS_MASK)
                              != CAM_REQ_INPROG)
                                  break;
                          DELAY(1000);
                  }
                  if (timeout == 0) {
                          /*
                           * XXX Is it worth adding a sim_timeout entry
                           * point so we can attempt recovery?  If
                           * this is only used for dumps, I don't think
                           * it is.
                           */
                          start_ccb->ccb_h.status = CAM_CMD_TIMEOUT;
                  }
          } else {
                  start_ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
          }
          splx(s);
  }
          
  /*
   * Schedule a peripheral driver to receive a ccb when it's
   * target device has space for more transactions.
   */
  void
  xpt_schedule(struct cam_periph *perph, u_int32_t new_priority)
  {
          struct cam_ed *device;
          int s;
          int runq;
  
          CAM_DEBUG(perph->path, CAM_DEBUG_TRACE, ("xpt_schedule\n"));
          device = perph->path->device;
          s = splsoftcam();
          if (periph_is_queued(perph)) {
                  /* Simply reorder based on new priority */
                  CAM_DEBUG(perph->path, CAM_DEBUG_SUBTRACE,
                            ("   change priority to %d\n", new_priority));
                  if (new_priority < perph->pinfo.priority) {
                          camq_change_priority(&device->drvq,
                                               perph->pinfo.index,
                                               new_priority);
                  }
                  runq = 0;
          } else {
                  /* New entry on the queue */
                  CAM_DEBUG(perph->path, CAM_DEBUG_SUBTRACE,
                            ("   added periph to queue\n"));
                  perph->pinfo.priority = new_priority;
                  perph->pinfo.generation = ++device->drvq.generation;
                  camq_insert(&device->drvq, &perph->pinfo);
                  runq = xpt_schedule_dev_allocq(perph->path->bus, device);
          }
          splx(s);
          if (runq != 0) {
                  CAM_DEBUG(perph->path, CAM_DEBUG_SUBTRACE,
                            ("   calling xpt_run_devq\n"));
                  xpt_run_dev_allocq(perph->path->bus);
          }
  }
  
  
  /*
   * Schedule a device to run on a given queue.
   * If the device was inserted as a new entry on the queue,
   * return 1 meaning the device queue should be run. If we
   * were already queued, implying someone else has already
   * started the queue, return 0 so the caller doesn't attempt
   * to run the queue.  Must be run at either splsoftcam
   * (or splcam since that encompases splsoftcam).
   */
  static int
  xpt_schedule_dev(struct camq *queue, cam_pinfo *pinfo,
                   u_int32_t new_priority)
  {
          int retval;
          u_int32_t old_priority;
  
          CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_schedule_dev\n"));
  
          old_priority = pinfo->priority;
  
          /*
           * Are we already queued?
           */
          if (pinfo->index != CAM_UNQUEUED_INDEX) {
                  /* Simply reorder based on new priority */
                  if (new_priority < old_priority) {
                          camq_change_priority(queue, pinfo->index,
                                               new_priority);
                          CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                                          ("changed priority to %d\n",
                                           new_priority));
                  }
                  retval = 0;
          } else {
                  /* New entry on the queue */
                  if (new_priority < old_priority)
                          pinfo->priority = new_priority;
  
                  CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                                  ("Inserting onto queue\n"));
                  pinfo->generation = ++queue->generation;
                  camq_insert(queue, pinfo);
                  retval = 1;
          }
          return (retval);
  }
  
  static void
  xpt_run_dev_allocq(struct cam_eb *bus)
  {
          struct  cam_devq *devq;
          int     s;
  
          CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_run_dev_allocq\n"));
          devq = bus->sim->devq;
  
          CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                          ("   qfrozen_cnt == 0x%x, entries == %d, "
                           "openings == %d, active == %d\n",
                           devq->alloc_queue.qfrozen_cnt,
                           devq->alloc_queue.entries,
                           devq->alloc_openings,
                           devq->alloc_active));
  
          s = splsoftcam();
          devq->alloc_queue.qfrozen_cnt++;
          while ((devq->alloc_queue.entries > 0)
              && (devq->alloc_openings > 0)
              && (devq->alloc_queue.qfrozen_cnt <= 1)) {
                  struct  cam_ed_qinfo *qinfo;
                  struct  cam_ed *device;
                  union   ccb *work_ccb;
                  struct  cam_periph *drv;
                  struct  camq *drvq;
                  
                  qinfo = (struct cam_ed_qinfo *)camq_remove(&devq->alloc_queue,
                                                             CAMQ_HEAD);
                  device = qinfo->device;
  
                  CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                                  ("running device %p\n", device));
  
                  drvq = &device->drvq;
  
  #ifdef CAMDEBUG
                  if (drvq->entries <= 0) {
                          panic("xpt_run_dev_allocq: "
                                "Device on queue without any work to do");
                  }
  #endif
                  if ((work_ccb = xpt_get_ccb(device)) != NULL) {
                          devq->alloc_openings--;
                          devq->alloc_active++;
                          drv = (struct cam_periph*)camq_remove(drvq, CAMQ_HEAD);
                          splx(s);
                          xpt_setup_ccb(&work_ccb->ccb_h, drv->path,
                                        drv->pinfo.priority);
                          CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                                          ("calling periph start\n"));
                          drv->periph_start(drv, work_ccb);
                  } else {
                          /*
                           * Malloc failure in alloc_ccb
                           */
                          /*
                           * XXX add us to a list to be run from free_ccb
                           * if we don't have any ccbs active on this
                           * device queue otherwise we may never get run
                           * again.
                           */
                          break;
                  }
          
                  /* Raise IPL for possible insertion and test at top of loop */
                  s = splsoftcam();
  
                  if (drvq->entries > 0) {
                          /* We have more work.  Attempt to reschedule */
                          xpt_schedule_dev_allocq(bus, device);
                  }
          }
          devq->alloc_queue.qfrozen_cnt--;
          splx(s);
  }
  
  static void
  xpt_run_dev_sendq(struct cam_eb *bus)
  {
          struct  cam_devq *devq;
          int     s;
  
          CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_run_dev_sendq\n"));
          
          devq = bus->sim->devq;
  
          s = splcam();
          devq->send_queue.qfrozen_cnt++;
          splx(s);
          s = splsoftcam();
          while ((devq->send_queue.entries > 0)
              && (devq->send_openings > 0)) {
                  struct  cam_ed_qinfo *qinfo;
                  struct  cam_ed *device;
                  union ccb *work_ccb;
                  struct  cam_sim *sim;
                  int     ospl;
  
                  ospl = splcam();
                  if (devq->send_queue.qfrozen_cnt > 1) {
                          splx(ospl);
                          break;
                  }
  
                  qinfo = (struct cam_ed_qinfo *)camq_remove(&devq->send_queue,
                                                             CAMQ_HEAD);
                  device = qinfo->device;
  
                  /*
                   * If the device has been "frozen", don't attempt
                   * to run it.
                   */
                  if (device->qfrozen_cnt > 0) {
                          splx(ospl);
                          continue;
                  }
  
                  CAM_DEBUG_PRINT(CAM_DEBUG_XPT,
                                  ("running device %p\n", device));
  
                  work_ccb = cam_ccbq_peek_ccb(&device->ccbq, CAMQ_HEAD);
                  if (work_ccb == NULL) {
                          printf("device on run queue with no ccbs???\n");
                          splx(ospl);
                          continue;
                  }
  
                  if ((work_ccb->ccb_h.flags & CAM_HIGH_POWER) != 0) {
  
                          if (num_highpower <= 0) {
                                  /*
                                   * We got a high power command, but we
                                   * don't have any available slots.  Freeze
                                   * the device queue until we have a slot
                                   * available.
                                   */
                                  device->qfrozen_cnt++;
                                  STAILQ_INSERT_TAIL(&highpowerq, 
                                                     &work_ccb->ccb_h, 
                                                     xpt_links.stqe);
  
                                  splx(ospl);
                                  continue;
                          } else {
                                  /*
                                   * Consume a high power slot while
                                   * this ccb runs.
                                   */
                                  num_highpower--;
                          }
                  }
                  devq->active_dev = device;
                  cam_ccbq_remove_ccb(&device->ccbq, work_ccb);
  
                  cam_ccbq_send_ccb(&device->ccbq, work_ccb);
                  splx(ospl);
  
                  devq->send_openings--;
                  devq->send_active++;            
                  
                  if (device->ccbq.queue.entries > 0)
                          xpt_schedule_dev_sendq(bus, device);
  
                  if (work_ccb && (work_ccb->ccb_h.flags & CAM_DEV_QFREEZE) != 0){
                          /*
                           * The client wants to freeze the queue
                           * after this CCB is sent.
                           */
                          ospl = splcam();
                          device->qfrozen_cnt++;
                          splx(ospl);
                  }
                  
                  splx(s);
  
                  /* In Target mode, the peripheral driver knows best... */
                  if (work_ccb->ccb_h.func_code == XPT_SCSI_IO) {
                          if ((device->inq_flags & SID_CmdQue) != 0
                           && work_ccb->csio.tag_action != CAM_TAG_ACTION_NONE)
                                  work_ccb->ccb_h.flags |= CAM_TAG_ACTION_VALID;
                          else
                                  /*
                                   * Clear this in case of a retried CCB that
                                   * failed due to a rejected tag.
                                   */
                                  work_ccb->ccb_h.flags &= ~CAM_TAG_ACTION_VALID;
                  }
  
                  /*
                   * Device queues can be shared among multiple sim instances
                   * that reside on different busses.  Use the SIM in the queue
                   * CCB's path, rather than the one in the bus that was passed
                   * into this function.
                   */
                  sim = work_ccb->ccb_h.path->bus->sim;
                  (*(sim->sim_action))(sim, work_ccb);
  
                  ospl = splcam();
                  devq->active_dev = NULL;
                  splx(ospl);
                  /* Raise IPL for possible insertion and test at top of loop */
                  s = splsoftcam();
          }
          splx(s);
          s = splcam();
          devq->send_queue.qfrozen_cnt--;
          splx(s);
  }
  
  /*
   * This function merges stuff from the slave ccb into the master ccb, while
   * keeping important fields in the master ccb constant.
   */
  void
  xpt_merge_ccb(union ccb *master_ccb, union ccb *slave_ccb)
  {
          /*
           * Pull fields that are valid for peripheral drivers to set
           * into the master CCB along with the CCB "payload".
           */
          master_ccb->ccb_h.retry_count = slave_ccb->ccb_h.retry_count;
          master_ccb->ccb_h.func_code = slave_ccb->ccb_h.func_code;
          master_ccb->ccb_h.timeout = slave_ccb->ccb_h.timeout;
          master_ccb->ccb_h.flags = slave_ccb->ccb_h.flags;
          bcopy(&(&slave_ccb->ccb_h)[1], &(&master_ccb->ccb_h)[1],
                sizeof(union ccb) - sizeof(struct ccb_hdr));
  }
  
  void
  xpt_setup_ccb(struct ccb_hdr *ccb_h, struct cam_path *path, u_int32_t priority)
  {
          CAM_DEBUG(path, CAM_DEBUG_TRACE, ("xpt_setup_ccb\n"));
          ccb_h->pinfo.priority = priority;
          ccb_h->path = path;
          ccb_h->path_id = path->bus->path_id;
          if (path->target)
                  ccb_h->target_id = path->target->target_id;
          else
                  ccb_h->target_id = CAM_TARGET_WILDCARD;
          if (path->device) {
                  ccb_h->target_lun = path->device->lun_id;
                  ccb_h->pinfo.generation = ++path->device->ccbq.queue.generation;
          } else {
                  ccb_h->target_lun = CAM_TARGET_WILDCARD;
          }
          ccb_h->pinfo.index = CAM_UNQUEUED_INDEX;
          ccb_h->flags = 0;
  }
  
  /* Path manipulation functions */
  cam_status
  xpt_create_path(struct cam_path **new_path_ptr, struct cam_periph *perph,
                  path_id_t path_id, target_id_t target_id, lun_id_t lun_id)
  {
          struct     cam_path *path;
          cam_status status;
  
          path = (struct cam_path *)malloc(sizeof(*path), M_DEVBUF, M_NOWAIT);
  
          if (path == NULL) {
                  status = CAM_RESRC_UNAVAIL;
                  return(status);
          }
          status = xpt_compile_path(path, perph, path_id, target_id, lun_id);
          if (status != CAM_REQ_CMP) {
                  free(path, M_DEVBUF);
                  path = NULL;
          }
          *new_path_ptr = path;
          return (status);
  }
  
  static cam_status
  xpt_compile_path(struct cam_path *new_path, struct cam_periph *perph,
                   path_id_t path_id, target_id_t target_id, lun_id_t lun_id)
  {
          struct       cam_eb *bus;
          struct       cam_et *target;
          struct       cam_ed *device;
          cam_status   status;
          int          s;
  
          status = CAM_REQ_CMP;   /* Completed without error */
          target = NULL;          /* Wildcarded */
          device = NULL;          /* Wildcarded */
  
          /*
           * We will potentially modify the EDT, so block interrupts
           * that may attempt to create cam paths.
           */
          s = splcam();
          bus = xpt_find_bus(path_id);
          if (bus == NULL) {
                  status = CAM_PATH_INVALID;
          } else {
                  target = xpt_find_target(bus, target_id);
                  if (target == NULL) {
                          /* Create one */
                          struct cam_et *new_target;
  
                          new_target = xpt_alloc_target(bus, target_id);
                          if (new_target == NULL) {
                                  status = CAM_RESRC_UNAVAIL;
                          } else {
                                  target = new_target;
                          }
                  }
                  if (target != NULL) {
                          device = xpt_find_device(target, lun_id);
                          if (device == NULL) {
                                  /* Create one */
                                  struct cam_ed *new_device;
  
                                  new_device = xpt_alloc_device(bus,
                                                                target,
                                                                lun_id);
                                  if (new_device == NULL) {
                                          status = CAM_RESRC_UNAVAIL;
                                  } else {
                                          device = new_device;
                                  }
                          }
                  }
          }
          splx(s);
  
          /*
           * Only touch the user's data if we are successful.
           */
          if (status == CAM_REQ_CMP) {
                  new_path->periph = perph;
                  new_path->bus = bus;
                  new_path->target = target;
                  new_path->device = device;
                  CAM_DEBUG(new_path, CAM_DEBUG_TRACE, ("xpt_compile_path\n"));
          } else {
                  if (device != NULL)
                          xpt_release_device(bus, target, device);
                  if (target != NULL)
                          xpt_release_target(bus, target);
                  if (bus != NULL)
                          xpt_release_bus(bus);
          }
          return (status);
  }
  
  static void
  xpt_release_path(struct cam_path *path)
  {
          CAM_DEBUG(path, CAM_DEBUG_TRACE, ("xpt_release_path\n"));
          if (path->device != NULL) {
                  xpt_release_device(path->bus, path->target, path->device);
                  path->device = NULL;
          }
          if (path->target != NULL) {
                  xpt_release_target(path->bus, path->target);
                  path->target = NULL;
          }
          if (path->bus != NULL) {
                  xpt_release_bus(path->bus);
                  path->bus = NULL;
          }
  }
  
  void
  xpt_free_path(struct cam_path *path)
  {
          CAM_DEBUG(path, CAM_DEBUG_TRACE, ("xpt_free_path\n"));
          xpt_release_path(path);
          free(path, M_DEVBUF);
  }
  
  
  /*
   * Return -1 for failure, 0 for exact match, 1 for match with wildcards
   * in path1, 2 for match with wildcards in path2.
   */
  int
  xpt_path_comp(struct cam_path *path1, struct cam_path *path2)
  {
          int retval = 0;
  
          if (path1->bus != path2->bus) {
                  if (path1->bus->path_id == CAM_BUS_WILDCARD)
                          retval = 1;
                  else if (path2->bus->path_id == CAM_BUS_WILDCARD)
                          retval = 2;
                  else
                          return (-1);
          }
          if (path1->target != path2->target) {
                  if (path1->target->target_id == CAM_TARGET_WILDCARD) {
                          if (retval == 0)
                                  retval = 1;
                  } else if (path2->target->target_id == CAM_TARGET_WILDCARD)
                          retval = 2;
                  else
                          return (-1);
          }
          if (path1->device != path2->device) {
                  if (path1->device->lun_id == CAM_LUN_WILDCARD) {
                          if (retval == 0)
                                  retval = 1;
                  } else if (path2->device->lun_id == CAM_LUN_WILDCARD)
                          retval = 2;
                  else
                          return (-1);
          }
          return (retval);
  }
  
  void
  xpt_print_path(struct cam_path *path)
  {
          if (path == NULL)
                  printf("(nopath): ");
          else {
                  if (path->periph != NULL)
                          printf("(%s%d:", path->periph->periph_name,
                                 path->periph->unit_number);
                  else
                          printf("(noperiph:");
  
                  if (path->bus != NULL)
                          printf("%s%d:%d:", path->bus->sim->sim_name,
                                 path->bus->sim->unit_number,
                                 path->bus->sim->bus_id);
                  else
                          printf("nobus:");
  
                  if (path->target != NULL)
                          printf("%d:", path->target->target_id);
                  else
                          printf("X:");
  
                  if (path->device != NULL)
                          printf("%d): ", path->device->lun_id);
                  else
                          printf("X): ");
          }
  }
  
  void
  xpt_print(struct cam_path *path, const char *fmt, ...)
  {
          va_list ap;
          xpt_print_path(path);
          va_start(ap, fmt);
          vprintf(fmt, ap);
          va_end(ap);
  }
  
  path_id_t
  xpt_path_path_id(struct cam_path *path)
  {
          return(path->bus->path_id);
  }
  
  target_id_t
  xpt_path_target_id(struct cam_path *path)
  {
          if (path->target != NULL)
                  return (path->target->target_id);
          else
                  return (CAM_TARGET_WILDCARD);
  }
  
  lun_id_t
  xpt_path_lun_id(struct cam_path *path)
  {
          if (path->device != NULL)
                  return (path->device->lun_id);
          else
                  return (CAM_LUN_WILDCARD);
  }
  
  struct cam_sim *
  xpt_path_sim(struct cam_path *path)
  {
          return (path->bus->sim);
  }
  
  struct cam_periph*
  xpt_path_periph(struct cam_path *path)
  {
          return (path->periph);
  }
  
  /*
   * Release a CAM control block for the caller.  Remit the cost of the structure
   * to the device referenced by the path.  If the this device had no 'credits'
   * and peripheral drivers have registered async callbacks for this notification
   * call them now.
   */
  void
  xpt_release_ccb(union ccb *free_ccb)
  {
          int      s;
          struct   cam_path *path;
          struct   cam_ed *device;
          struct   cam_eb *bus;
  
          CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_release_ccb\n"));
          path = free_ccb->ccb_h.path;
          device = path->device;
          bus = path->bus;
          s = splsoftcam();
          cam_ccbq_release_opening(&device->ccbq);
          if (xpt_ccb_count > xpt_max_ccbs) {
                  xpt_free_ccb(free_ccb);
                  xpt_ccb_count--;
          } else {
                  SLIST_INSERT_HEAD(&ccb_freeq, &free_ccb->ccb_h, xpt_links.sle);
          }
          bus->sim->devq->alloc_openings++;
          bus->sim->devq->alloc_active--;
          /* XXX Turn this into an inline function - xpt_run_device?? */
          if ((device_is_alloc_queued(device) == 0)
           && (device->drvq.entries > 0)) {
                  xpt_schedule_dev_allocq(bus, device);
          }
          splx(s);
          if (dev_allocq_is_runnable(bus->sim->devq))
                  xpt_run_dev_allocq(bus);
  }
  
  /* Functions accessed by SIM drivers */
  
  /*
   * A sim structure, listing the SIM entry points and instance
   * identification info is passed to xpt_bus_register to hook the SIM
   * into the CAM framework.  xpt_bus_register creates a cam_eb entry
   * for this new bus and places it in the array of busses and assigns
   * it a path_id.  The path_id may be influenced by "hard wiring"
   * information specified by the user.  Once interrupt services are
   * availible, the bus will be probed.
   */
  int32_t
  xpt_bus_register(struct cam_sim *sim, u_int32_t bus)
  {
          struct cam_eb *new_bus;
          struct cam_eb *old_bus;
          struct ccb_pathinq cpi;
          int s;
  
          sim->bus_id = bus;
          new_bus = (struct cam_eb *)malloc(sizeof(*new_bus),
                                            M_DEVBUF, M_NOWAIT);
          if (new_bus == NULL) {
                  /* Couldn't satisfy request */
                  return (CAM_RESRC_UNAVAIL);
          }
  
          if (strcmp(sim->sim_name, "xpt") != 0) {
  
                  sim->path_id =
                      xptpathid(sim->sim_name, sim->unit_number, sim->bus_id);
          }
  
          TAILQ_INIT(&new_bus->et_entries);
          new_bus->path_id = sim->path_id;
          new_bus->sim = sim;
          timevalclear(&new_bus->last_reset);
          new_bus->flags = 0;
          new_bus->refcount = 1;  /* Held until a bus_deregister event */
          new_bus->generation = 0;
          s = splcam();
          old_bus = TAILQ_FIRST(&xpt_busses);
          while (old_bus != NULL
              && old_bus->path_id < new_bus->path_id)
                  old_bus = TAILQ_NEXT(old_bus, links);
          if (old_bus != NULL)
                  TAILQ_INSERT_BEFORE(old_bus, new_bus, links);
          else
                  TAILQ_INSERT_TAIL(&xpt_busses, new_bus, links);
          bus_generation++;
          splx(s);
  
          /* Notify interested parties */
          if (sim->path_id != CAM_XPT_PATH_ID) {
                  struct cam_path path;
  
                  xpt_compile_path(&path, /*periph*/NULL, sim->path_id,
                                   CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD);
                  xpt_setup_ccb(&cpi.ccb_h, &path, /*priority*/1);
                  cpi.ccb_h.func_code = XPT_PATH_INQ;
                  xpt_action((union ccb *)&cpi);
                  xpt_async(AC_PATH_REGISTERED, xpt_periph->path, &cpi);
                  xpt_release_path(&path);
          }
          return (CAM_SUCCESS);
  }
  
  int32_t
  xpt_bus_deregister(path_id_t pathid)
  {
          struct cam_path bus_path;
          cam_status status;
  
          status = xpt_compile_path(&bus_path, NULL, pathid,
                                    CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD);
          if (status != CAM_REQ_CMP)
                  return (status);
  
          xpt_async(AC_LOST_DEVICE, &bus_path, NULL);
          xpt_async(AC_PATH_DEREGISTERED, &bus_path, NULL);
          
          /* Release the reference count held while registered. */
          xpt_release_bus(bus_path.bus);
          xpt_release_path(&bus_path);
  
          return (CAM_REQ_CMP);
  }
  
  static path_id_t
  xptnextfreepathid(void)
  {
          struct cam_eb *bus;
          path_id_t pathid;
          char *strval;
  
          pathid = 0;
          bus = TAILQ_FIRST(&xpt_busses);
  retry:
          /* Find an unoccupied pathid */
          while (bus != NULL
              && bus->path_id <= pathid) {
                  if (bus->path_id == pathid)
                          pathid++;
                  bus = TAILQ_NEXT(bus, links);
          }
  
          /*
           * Ensure that this pathid is not reserved for
           * a bus that may be registered in the future.
           */
          if (resource_string_value("scbus", pathid, "at", &strval) == 0) {
                  ++pathid;
                  /* Start the search over */
                  goto retry;
          }
          return (pathid);
  }
  
  static path_id_t
  xptpathid(const char *sim_name, int sim_unit, int sim_bus)
  {
          path_id_t pathid;
          int i, dunit, val;
          char buf[32], *strval;
  
          pathid = CAM_XPT_PATH_ID;
          snprintf(buf, sizeof(buf), "%s%d", sim_name, sim_unit);
          i = -1;
          while ((i = resource_locate(i, "scbus")) != -1) {
                  dunit = resource_query_unit(i);
                  if (dunit < 0)          /* unwired?! */
                          continue;
                  if (resource_string_value("scbus", dunit, "at", &strval) != 0)
                          continue;
                  if (strcmp(buf, strval) != 0)
                          continue;
                  if (resource_int_value("scbus", dunit, "bus", &val) == 0) {
                          if (sim_bus == val) {
                                  pathid = dunit;
                                  break;
                          }
                  } else if (sim_bus == 0) {
                          /* Unspecified matches bus 0 */
                          pathid = dunit;
                          break;
                  } else {
                          printf("Ambiguous scbus configuration for %s%d "
                                 "bus %d, cannot wire down.  The kernel "
                                 "config entry for scbus%d should "
                                 "specify a controller bus.\n"
                                 "Scbus will be assigned dynamically.\n",
                                 sim_name, sim_unit, sim_bus, dunit);
                          break;
                  }
          }
  
          if (pathid == CAM_XPT_PATH_ID)
                  pathid = xptnextfreepathid();
          return (pathid);
  }
  
  void
  xpt_async(u_int32_t async_code, struct cam_path *path, void *async_arg)
  {
          struct cam_eb *bus;
          struct cam_et *target, *next_target;
          struct cam_ed *device, *next_device;
          int s;
  
          CAM_DEBUG(path, CAM_DEBUG_TRACE, ("xpt_async\n"));
  
          /*
           * Most async events come from a CAM interrupt context.  In
           * a few cases, the error recovery code at the peripheral layer,
           * which may run from our SWI or a process context, may signal
           * deferred events with a call to xpt_async. Ensure async
           * notifications are serialized by blocking cam interrupts.
           */
          s = splcam();
  
          bus = path->bus;
  
          if (async_code == AC_BUS_RESET) { 
                  int s;
  
                  s = splclock();
                  /* Update our notion of when the last reset occurred */
                  microtime(&bus->last_reset);
                  splx(s);
          }
  
          for (target = TAILQ_FIRST(&bus->et_entries);
               target != NULL;
               target = next_target) {
  
                  next_target = TAILQ_NEXT(target, links);
  
                  if (path->target != target
                   && path->target->target_id != CAM_TARGET_WILDCARD
                   && target->target_id != CAM_TARGET_WILDCARD)
                          continue;
  
                  if (async_code == AC_SENT_BDR) {
                          int s;
  
                          /* Update our notion of when the last reset occurred */
                          s = splclock();
                          microtime(&path->target->last_reset);
                          splx(s);
                  }
  
                  for (device = TAILQ_FIRST(&target->ed_entries);
                       device != NULL;
                       device = next_device) {
  
                          next_device = TAILQ_NEXT(device, links);
  
                          if (path->device != device 
                           && path->device->lun_id != CAM_LUN_WILDCARD
                           && device->lun_id != CAM_LUN_WILDCARD)
                                  continue;
  
                          xpt_dev_async(async_code, bus, target,
                                        device, async_arg);
  
                          xpt_async_bcast(&device->asyncs, async_code,
                                          path, async_arg);
                  }
          }
          
          /*
           * If this wasn't a fully wildcarded async, tell all
           * clients that want all async events.
           */
          if (bus != xpt_periph->path->bus)
                  xpt_async_bcast(&xpt_periph->path->device->asyncs, async_code,
                                  path, async_arg);
          splx(s);
  }
  
  static void
  xpt_async_bcast(struct async_list *async_head,
                  u_int32_t async_code,
                  struct cam_path *path, void *async_arg)
  {
          struct async_node *cur_entry;
  
          cur_entry = SLIST_FIRST(async_head);
          while (cur_entry != NULL) {
                  struct async_node *next_entry;
                  /*
                   * Grab the next list entry before we call the current
                   * entry's callback.  This is because the callback function
                   * can delete its async callback entry.
                   */
                  next_entry = SLIST_NEXT(cur_entry, links);
                  if ((cur_entry->event_enable & async_code) != 0)
                          cur_entry->callback(cur_entry->callback_arg,
                                              async_code, path,
                                              async_arg);
                  cur_entry = next_entry;
          }
  }
  
  /*
   * Handle any per-device event notifications that require action by the XPT.
   */
  static void
  xpt_dev_async(u_int32_t async_code, struct cam_eb *bus, struct cam_et *target,
                struct cam_ed *device, void *async_arg)
  {
          cam_status status;
          struct cam_path newpath;
  
          /*
           * We only need to handle events for real devices.
           */
          if (target->target_id == CAM_TARGET_WILDCARD
           || device->lun_id == CAM_LUN_WILDCARD)
                  return;
  
          /*
           * We need our own path with wildcards expanded to
           * handle certain types of events.
           */
          if ((async_code == AC_SENT_BDR)
           || (async_code == AC_BUS_RESET)
           || (async_code == AC_INQ_CHANGED))
                  status = xpt_compile_path(&newpath, NULL,
                                            bus->path_id,
                                            target->target_id,
                                            device->lun_id);
          else
                  status = CAM_REQ_CMP_ERR;
  
          if (status == CAM_REQ_CMP) {
  
                  /*
                   * Allow transfer negotiation to occur in a
                   * tag free environment.
                   */
                  if (async_code == AC_SENT_BDR
                   || async_code == AC_BUS_RESET)
                          xpt_toggle_tags(&newpath);
  
                  if (async_code == AC_INQ_CHANGED) {
                          /*
                           * We've sent a start unit command, or
                           * something similar to a device that
                           * may have caused its inquiry data to
                           * change. So we re-scan the device to
                           * refresh the inquiry data for it.
                           */
                          xpt_scan_lun(newpath.periph, &newpath,
                                       CAM_EXPECT_INQ_CHANGE, NULL);
                  }
                  xpt_release_path(&newpath);
          } else if (async_code == AC_LOST_DEVICE) {
                  device->flags |= CAM_DEV_UNCONFIGURED;
          } else if (async_code == AC_TRANSFER_NEG) {
                  struct ccb_trans_settings *settings;
  
                  settings = (struct ccb_trans_settings *)async_arg;
                  xpt_set_transfer_settings(settings, device,
                                            /*async_update*/TRUE);
          }
  }
  
  u_int32_t
  xpt_freeze_devq(struct cam_path *path, u_int count)
  {
          int s;
          struct ccb_hdr *ccbh;
  
          s = splcam();
          path->device->qfrozen_cnt += count;
  
          /*
           * Mark the last CCB in the queue as needing
           * to be requeued if the driver hasn't
           * changed it's state yet.  This fixes a race
           * where a ccb is just about to be queued to
           * a controller driver when it's interrupt routine
           * freezes the queue.  To completly close the
           * hole, controller drives must check to see
           * if a ccb's status is still CAM_REQ_INPROG
           * under spl protection just before they queue
           * the CCB.  See ahc_action/ahc_freeze_devq for
           * an example.
           */
          ccbh = TAILQ_LAST(&path->device->ccbq.active_ccbs, ccb_hdr_tailq);
          if (ccbh && ccbh->status == CAM_REQ_INPROG)
                  ccbh->status = CAM_REQUEUE_REQ;
          splx(s);
          return (path->device->qfrozen_cnt);
  }
  
  u_int32_t
  xpt_freeze_simq(struct cam_sim *sim, u_int count)
  {
          sim->devq->send_queue.qfrozen_cnt += count;
          if (sim->devq->active_dev != NULL) {
                  struct ccb_hdr *ccbh;
                  
                  ccbh = TAILQ_LAST(&sim->devq->active_dev->ccbq.active_ccbs,
                                    ccb_hdr_tailq);
                  if (ccbh && ccbh->status == CAM_REQ_INPROG)
                          ccbh->status = CAM_REQUEUE_REQ;
          }
          return (sim->devq->send_queue.qfrozen_cnt);
  }
  
  static void
  xpt_release_devq_timeout(void *arg)
  {
          struct cam_ed *device;
  
          device = (struct cam_ed *)arg;
  
          xpt_release_devq_device(device, /*count*/1, /*run_queue*/TRUE);
  }
  
  void
  xpt_release_devq(struct cam_path *path, u_int count, int run_queue)
  {
          xpt_release_devq_device(path->device, count, run_queue);
  }
  
  static void
  xpt_release_devq_device(struct cam_ed *dev, u_int count, int run_queue)
  {
          int     rundevq;
          int     s0, s1;
  
          rundevq = 0;
          s0 = splsoftcam();
          s1 = splcam();
          if (dev->qfrozen_cnt > 0) {
  
                  count = (count > dev->qfrozen_cnt) ? dev->qfrozen_cnt : count;
                  dev->qfrozen_cnt -= count;
                  if (dev->qfrozen_cnt == 0) {
  
                          /*
                           * No longer need to wait for a successful
                           * command completion.
                           */
                          dev->flags &= ~CAM_DEV_REL_ON_COMPLETE;
  
                          /*
                           * Remove any timeouts that might be scheduled
                           * to release this queue.
                           */
                          if ((dev->flags & CAM_DEV_REL_TIMEOUT_PENDING) != 0) {
                                  untimeout(xpt_release_devq_timeout, dev,
                                            dev->c_handle);
                                  dev->flags &= ~CAM_DEV_REL_TIMEOUT_PENDING;
                          }
  
                          /*
                           * Now that we are unfrozen schedule the
                           * device so any pending transactions are
                           * run.
                           */
                          if ((dev->ccbq.queue.entries > 0)
                           && (xpt_schedule_dev_sendq(dev->target->bus, dev))
                           && (run_queue != 0)) {
                                  rundevq = 1;
                          }
                  }
          }
          splx(s1);
          if (rundevq != 0)
                  xpt_run_dev_sendq(dev->target->bus);
          splx(s0);
  }
  
  void
  xpt_release_simq(struct cam_sim *sim, int run_queue)
  {
          int     s;
          struct  camq *sendq;
  
          sendq = &(sim->devq->send_queue);
          s = splcam();
          if (sendq->qfrozen_cnt > 0) {
  
                  sendq->qfrozen_cnt--;
                  if (sendq->qfrozen_cnt == 0) {
                          struct cam_eb *bus;
  
                          /*
                           * If there is a timeout scheduled to release this
                           * sim queue, remove it.  The queue frozen count is
                           * already at 0.
                           */
                          if ((sim->flags & CAM_SIM_REL_TIMEOUT_PENDING) != 0){
                                  untimeout(xpt_release_simq_timeout, sim,
                                            sim->c_handle);
                                  sim->flags &= ~CAM_SIM_REL_TIMEOUT_PENDING;
                          }
                          bus = xpt_find_bus(sim->path_id);
                          splx(s);
  
                          if (run_queue) {
                                  /*
                                   * Now that we are unfrozen run the send queue.
                                   */
                                  xpt_run_dev_sendq(bus);
                          }
                          xpt_release_bus(bus);
                  } else
                          splx(s);
          } else
                  splx(s);
  }
  
  static void
  xpt_release_simq_timeout(void *arg)
  {
          struct cam_sim *sim;
  
          sim = (struct cam_sim *)arg;
          xpt_release_simq(sim, /* run_queue */ TRUE);
  }
  
  void
  xpt_done(union ccb *done_ccb)
  {
          int s;
  
          s = splcam();
  
          CAM_DEBUG(done_ccb->ccb_h.path, CAM_DEBUG_TRACE, ("xpt_done\n"));
          if ((done_ccb->ccb_h.func_code & XPT_FC_QUEUED) != 0) {
                  /*
                   * Queue up the request for handling by our SWI handler
                   * any of the "non-immediate" type of ccbs.
                   */
                  switch (done_ccb->ccb_h.path->periph->type) {
                  case CAM_PERIPH_BIO:
                          TAILQ_INSERT_TAIL(&cam_bioq, &done_ccb->ccb_h,
                                            sim_links.tqe);
                          done_ccb->ccb_h.pinfo.index = CAM_DONEQ_INDEX;
                          setsoftcambio();
                          break;
                  case CAM_PERIPH_NET:
                          TAILQ_INSERT_TAIL(&cam_netq, &done_ccb->ccb_h,
                                            sim_links.tqe);
                          done_ccb->ccb_h.pinfo.index = CAM_DONEQ_INDEX;
                          setsoftcamnet();
                          break;
                  }
          }
          splx(s);
  }
  
  union ccb *
  xpt_alloc_ccb()
  {
          union ccb *new_ccb;
  
          new_ccb = malloc(sizeof(*new_ccb), M_DEVBUF, M_WAITOK);
          return (new_ccb);
  }
  
  void
  xpt_free_ccb(union ccb *free_ccb)
  {
          free(free_ccb, M_DEVBUF);
  }
  
  
  
  /* Private XPT functions */
  
  /*
   * Get a CAM control block for the caller. Charge the structure to the device
   * referenced by the path.  If the this device has no 'credits' then the
   * device already has the maximum number of outstanding operations under way
   * and we return NULL. If we don't have sufficient resources to allocate more
   * ccbs, we also return NULL.
   */
  static union ccb *
  xpt_get_ccb(struct cam_ed *device)
  {
          union ccb *new_ccb;
          int s;
  
          s = splsoftcam();
          if ((new_ccb = (union ccb *)ccb_freeq.slh_first) == NULL) {
                  new_ccb = malloc(sizeof(*new_ccb), M_DEVBUF, M_NOWAIT);
                  if (new_ccb == NULL) {
                          splx(s);
                          return (NULL);
                  }
                  callout_handle_init(&new_ccb->ccb_h.timeout_ch);
                  SLIST_INSERT_HEAD(&ccb_freeq, &new_ccb->ccb_h,
                                    xpt_links.sle);
                  xpt_ccb_count++;
          }
          cam_ccbq_take_opening(&device->ccbq);
          SLIST_REMOVE_HEAD(&ccb_freeq, xpt_links.sle);
          splx(s);
          return (new_ccb);
  }
  
  static void
  xpt_release_bus(struct cam_eb *bus)
  {
          int s;
  
          s = splcam();
          if ((--bus->refcount == 0)
           && (TAILQ_FIRST(&bus->et_entries) == NULL)) {
                  TAILQ_REMOVE(&xpt_busses, bus, links);
                  bus_generation++;
                  splx(s);
                  free(bus, M_DEVBUF);
          } else
                  splx(s);
  }
  
  static struct cam_et *
  xpt_alloc_target(struct cam_eb *bus, target_id_t target_id)
  {
          struct cam_et *target;
  
          target = (struct cam_et *)malloc(sizeof(*target), M_DEVBUF, M_NOWAIT);
          if (target != NULL) {
                  struct cam_et *cur_target;
  
                  TAILQ_INIT(&target->ed_entries);
                  target->bus = bus;
                  target->target_id = target_id;
                  target->refcount = 1;
                  target->generation = 0;
                  timevalclear(&target->last_reset);
                  /*
                   * Hold a reference to our parent bus so it
                   * will not go away before we do.
                   */
                  bus->refcount++;
  
                  /* Insertion sort into our bus's target list */
                  cur_target = TAILQ_FIRST(&bus->et_entries);
                  while (cur_target != NULL && cur_target->target_id < target_id)
                          cur_target = TAILQ_NEXT(cur_target, links);
  
                  if (cur_target != NULL) {
                          TAILQ_INSERT_BEFORE(cur_target, target, links);
                  } else {
                          TAILQ_INSERT_TAIL(&bus->et_entries, target, links);
                  }
                  bus->generation++;
          }
          return (target);
  }
  
  static void
  xpt_release_target(struct cam_eb *bus, struct cam_et *target)
  {
          int s;
  
          s = splcam();
          if ((--target->refcount == 0)
           && (TAILQ_FIRST(&target->ed_entries) == NULL)) {
                  TAILQ_REMOVE(&bus->et_entries, target, links);
                  bus->generation++;
                  splx(s);
                  free(target, M_DEVBUF);
                  xpt_release_bus(bus);
          } else
                  splx(s);
  }
  
  static struct cam_ed *
  xpt_alloc_device(struct cam_eb *bus, struct cam_et *target, lun_id_t lun_id)
  {
          struct     cam_ed *device;
          struct     cam_devq *devq;
          cam_status status;
  
          /* Make space for us in the device queue on our bus */
          devq = bus->sim->devq;
          status = cam_devq_resize(devq, devq->alloc_queue.array_size + 1);
  
          if (status != CAM_REQ_CMP) {
                  device = NULL;
          } else {
                  device = (struct cam_ed *)malloc(sizeof(*device),
                                                   M_DEVBUF, M_NOWAIT);
          }
  
          if (device != NULL) {
                  struct cam_ed *cur_device;
  
                  cam_init_pinfo(&device->alloc_ccb_entry.pinfo);
                  device->alloc_ccb_entry.device = device;
                  cam_init_pinfo(&device->send_ccb_entry.pinfo);
                  device->send_ccb_entry.device = device;
                  device->target = target;
                  device->lun_id = lun_id;
                  /* Initialize our queues */
                  if (camq_init(&device->drvq, 0) != 0) {
                          free(device, M_DEVBUF);
                          return (NULL);
                  }
                  if (cam_ccbq_init(&device->ccbq,
                                    bus->sim->max_dev_openings) != 0) {
                          camq_fini(&device->drvq);
                          free(device, M_DEVBUF);
                          return (NULL);
                  }
                  SLIST_INIT(&device->asyncs);
                  SLIST_INIT(&device->periphs);
                  device->generation = 0;
                  device->owner = NULL;
                  /*
                   * Take the default quirk entry until we have inquiry
                   * data and can determine a better quirk to use.
                   */
                  device->quirk = &xpt_quirk_table[xpt_quirk_table_size - 1];
                  bzero(&device->inq_data, sizeof(device->inq_data));
                  device->inq_flags = 0;
                  device->queue_flags = 0;
                  device->serial_num = NULL;
                  device->serial_num_len = 0;
                  device->qfrozen_cnt = 0;
                  device->flags = CAM_DEV_UNCONFIGURED;
                  device->tag_delay_count = 0;
                  device->refcount = 1;
                  callout_handle_init(&device->c_handle);
  
                  /*
                   * Hold a reference to our parent target so it
                   * will not go away before we do.
                   */
                  target->refcount++;
  
                  /*
                   * XXX should be limited by number of CCBs this bus can
                   * do.
                   */
                  xpt_max_ccbs += device->ccbq.devq_openings;
                  /* Insertion sort into our target's device list */
                  cur_device = TAILQ_FIRST(&target->ed_entries);
                  while (cur_device != NULL && cur_device->lun_id < lun_id)
                          cur_device = TAILQ_NEXT(cur_device, links);
                  if (cur_device != NULL) {
                          TAILQ_INSERT_BEFORE(cur_device, device, links);
                  } else {
                          TAILQ_INSERT_TAIL(&target->ed_entries, device, links);
                  }
                  target->generation++;
          }
          return (device);
  }
  
  static void
  xpt_release_device(struct cam_eb *bus, struct cam_et *target,
                     struct cam_ed *device)
  {
          int s;
  
          s = splcam();
          if ((--device->refcount == 0)
           && ((device->flags & CAM_DEV_UNCONFIGURED) != 0)) {
                  struct cam_devq *devq;
  
                  if (device->alloc_ccb_entry.pinfo.index != CAM_UNQUEUED_INDEX
                   || device->send_ccb_entry.pinfo.index != CAM_UNQUEUED_INDEX)
                          panic("Removing device while still queued for ccbs");
  
                  if ((device->flags & CAM_DEV_REL_TIMEOUT_PENDING) != 0)
                                  untimeout(xpt_release_devq_timeout, device,
                                            device->c_handle);
  
                  TAILQ_REMOVE(&target->ed_entries, device,links);
                  target->generation++;
                  xpt_max_ccbs -= device->ccbq.devq_openings;
                  /* Release our slot in the devq */
                  devq = bus->sim->devq;
                  cam_devq_resize(devq, devq->alloc_queue.array_size - 1);
                  splx(s);
                  camq_fini(&device->drvq);
                  camq_fini(&device->ccbq.queue);
                  free(device, M_DEVBUF);
                  xpt_release_target(bus, target);
          } else
                  splx(s);
  }
  
  static u_int32_t
  xpt_dev_ccbq_resize(struct cam_path *path, int newopenings)
  {
          int     s;
          int     diff;
          int     result;
          struct  cam_ed *dev;
  
          dev = path->device;
          s = splsoftcam();
  
          diff = newopenings - (dev->ccbq.dev_active + dev->ccbq.dev_openings);
          result = cam_ccbq_resize(&dev->ccbq, newopenings);
          if (result == CAM_REQ_CMP && (diff < 0)) {
                  dev->flags |= CAM_DEV_RESIZE_QUEUE_NEEDED;
          }
          /* Adjust the global limit */
          xpt_max_ccbs += diff;
          splx(s);
          return (result);
  }
  
  static struct cam_eb *
  xpt_find_bus(path_id_t path_id)
  {
          struct cam_eb *bus;
  
          for (bus = TAILQ_FIRST(&xpt_busses);
               bus != NULL;
               bus = TAILQ_NEXT(bus, links)) {
                  if (bus->path_id == path_id) {
                          bus->refcount++;
                          break;
                  }
          }
          return (bus);
  }
  
  static struct cam_et *
  xpt_find_target(struct cam_eb *bus, target_id_t target_id)
  {
          struct cam_et *target;
  
          for (target = TAILQ_FIRST(&bus->et_entries);
               target != NULL;
               target = TAILQ_NEXT(target, links)) {
                  if (target->target_id == target_id) {
                          target->refcount++;
                          break;
                  }
          }
          return (target);
  }
  
  static struct cam_ed *
  xpt_find_device(struct cam_et *target, lun_id_t lun_id)
  {
          struct cam_ed *device;
  
          for (device = TAILQ_FIRST(&target->ed_entries);
               device != NULL;
               device = TAILQ_NEXT(device, links)) {
                  if (device->lun_id == lun_id) {
                          device->refcount++;
                          break;
                  }
          }
          return (device);
  }
  
  typedef struct {
          union   ccb *request_ccb;
          struct  ccb_pathinq *cpi;
          int     counter;
  } xpt_scan_bus_info;
  
  static void
  xpt_scan_bus(struct cam_periph *periph, union ccb *request_ccb)
  {
          CAM_DEBUG(request_ccb->ccb_h.path, CAM_DEBUG_TRACE,
                    ("xpt_scan_bus\n"));
          switch (request_ccb->ccb_h.func_code) {
          case XPT_SCAN_BUS:
          {
                  xpt_scan_bus_info *scan_info;
                  union   ccb *work_ccb;
                  struct  cam_path *path;
                  u_int i;
                  u_int max_target;
                  u_int initiator_id;
  
                  /* Find out the characteristics of the bus */
                  work_ccb = xpt_alloc_ccb();
                  xpt_setup_ccb(&work_ccb->ccb_h, request_ccb->ccb_h.path,
                      request_ccb->ccb_h.pinfo.priority);
                  work_ccb->ccb_h.func_code = XPT_PATH_INQ;
                  xpt_action(work_ccb);
                  if (work_ccb->ccb_h.status != CAM_REQ_CMP) {
                          request_ccb->ccb_h.status = work_ccb->ccb_h.status;
                          xpt_free_ccb(work_ccb);
                          xpt_done(request_ccb);
                          return;
                  }
  
                  if ((work_ccb->cpi.hba_misc & PIM_NOINITIATOR) != 0) {
                          /*
                           * Can't scan the bus on an adapter that
                           * cannot perform the initiator role.
                           */
                          request_ccb->ccb_h.status = CAM_REQ_CMP;
                          xpt_free_ccb(work_ccb);
                          xpt_done(request_ccb);
                          return;
                  }
  
                  /* Save some state for use while we probe for devices */
                  scan_info = (xpt_scan_bus_info *)
                      malloc(sizeof(xpt_scan_bus_info), M_TEMP, M_WAITOK);
                  scan_info->request_ccb = request_ccb;
                  scan_info->cpi = &work_ccb->cpi;
  
                  /* Cache on our stack so we can work asynchronously */
                  max_target = scan_info->cpi->max_target;
                  initiator_id = scan_info->cpi->initiator_id;
  
  
                  /*
                   * We can scan all targets in parallel, or do it sequentially.
                   */
                  if (scan_info->cpi->hba_misc & PIM_SEQSCAN) {
                          max_target = 0;
                          scan_info->counter = 0;
                  } else {
                          scan_info->counter = scan_info->cpi->max_target + 1;
                          if (scan_info->cpi->initiator_id < scan_info->counter) {
                                  scan_info->counter--;
                          }
                  }
                  
                  for (i = 0; i <= max_target; i++) {
                          cam_status status;
                          if (i == initiator_id)
                                  continue;
  
                          status = xpt_create_path(&path, xpt_periph,
                                                   request_ccb->ccb_h.path_id,
                                                   i, 0);
                          if (status != CAM_REQ_CMP) {
                                  printf("xpt_scan_bus: xpt_create_path failed"
                                         " with status %#x, bus scan halted\n",
                                         status);
                                  free(scan_info, M_TEMP);
                                  request_ccb->ccb_h.status = status;
                                  xpt_free_ccb(work_ccb);
                                  xpt_done(request_ccb);
                                  break;
                          }
                          work_ccb = xpt_alloc_ccb();
                          xpt_setup_ccb(&work_ccb->ccb_h, path,
                              request_ccb->ccb_h.pinfo.priority);
                          work_ccb->ccb_h.func_code = XPT_SCAN_LUN;
                          work_ccb->ccb_h.cbfcnp = xpt_scan_bus;
                          work_ccb->ccb_h.ppriv_ptr0 = scan_info;
                          work_ccb->crcn.flags = request_ccb->crcn.flags;
                          xpt_action(work_ccb);
                  }
                  break;
          }
          case XPT_SCAN_LUN:
          {
                  cam_status status;
                  struct cam_path *path;
                  xpt_scan_bus_info *scan_info;
                  path_id_t path_id;
                  target_id_t target_id;
                  lun_id_t lun_id;
  
                  /* Reuse the same CCB to query if a device was really found */
                  scan_info = (xpt_scan_bus_info *)request_ccb->ccb_h.ppriv_ptr0;
                  xpt_setup_ccb(&request_ccb->ccb_h, request_ccb->ccb_h.path,
                                request_ccb->ccb_h.pinfo.priority);
                  request_ccb->ccb_h.func_code = XPT_GDEV_TYPE;
  
                  path_id = request_ccb->ccb_h.path_id;
                  target_id = request_ccb->ccb_h.target_id;
                  lun_id = request_ccb->ccb_h.target_lun;
                  xpt_action(request_ccb);
  
  #if 0
                  printf("xpt_scan_bus: got back probe from %d:%d:%d\n",
                          path_id, target_id, lun_id);
  #endif
  
                  if (request_ccb->ccb_h.status != CAM_REQ_CMP) {
                          struct cam_ed *device;
                          struct cam_et *target;
                          int s, phl;
  
                          /*
                           * If we already probed lun 0 successfully, or
                           * we have additional configured luns on this
                           * target that might have "gone away", go onto
                           * the next lun.
                           */
                          target = request_ccb->ccb_h.path->target;
                          /*
                           * We may touch devices that we don't
                           * hold references too, so ensure they
                           * don't disappear out from under us.
                           * The target above is referenced by the
                           * path in the request ccb.
                           */
                          phl = 0;
                          s = splcam();
                          device = TAILQ_FIRST(&target->ed_entries);
                          if (device != NULL) {
                                  phl = device->quirk->quirks & CAM_QUIRK_HILUNS;
                                  if (device->lun_id == 0)
                                          device = TAILQ_NEXT(device, links);
                          }
                          splx(s);
                          if ((lun_id != 0) || (device != NULL)) {
                                  if (lun_id < (CAM_SCSI2_MAXLUN-1) || phl)
                                          lun_id++;
                          }
                  } else {
                          struct cam_ed *device;
                          
                          device = request_ccb->ccb_h.path->device;
  
                          if ((device->quirk->quirks & CAM_QUIRK_NOLUNS) == 0) {
                                  /* Try the next lun */
                                  if (lun_id < (CAM_SCSI2_MAXLUN-1) ||
                                      (device->quirk->quirks & CAM_QUIRK_HILUNS))
                                          lun_id++;
                          }
                  }
  
                  /*
                   * Free the current request path- we're done with it.
                   */
                  xpt_free_path(request_ccb->ccb_h.path);
  
                  /*
                   * Check to see if we scan any further luns.
                   */
                  if (lun_id == request_ccb->ccb_h.target_lun
                   || lun_id > scan_info->cpi->max_lun) {
                          int done;
  
   hop_again:
                          done = 0;
                          if (scan_info->cpi->hba_misc & PIM_SEQSCAN) {
                                  scan_info->counter++;
                                  if (scan_info->counter == 
                                      scan_info->cpi->initiator_id) {
                                          scan_info->counter++;
                                  }
                                  if (scan_info->counter >=
                                      scan_info->cpi->max_target+1) {
                                          done = 1;
                                  }
                          } else {
                                  scan_info->counter--;
                                  if (scan_info->counter == 0) {
                                          done = 1;
                                  }
                          }
                          if (done) {
                                  xpt_free_ccb(request_ccb);
                                  xpt_free_ccb((union ccb *)scan_info->cpi);
                                  request_ccb = scan_info->request_ccb;
                                  free(scan_info, M_TEMP);
                                  request_ccb->ccb_h.status = CAM_REQ_CMP;
                                  xpt_done(request_ccb);
                                  break;
                          }
  
                          if ((scan_info->cpi->hba_misc & PIM_SEQSCAN) == 0) {
                                  break;
                          }
                          status = xpt_create_path(&path, xpt_periph,
                              scan_info->request_ccb->ccb_h.path_id,
                              scan_info->counter, 0);
                          if (status != CAM_REQ_CMP) {
                                  printf("xpt_scan_bus: xpt_create_path failed"
                                      " with status %#x, bus scan halted\n",
                                      status);
                                  xpt_free_ccb(request_ccb);
                                  xpt_free_ccb((union ccb *)scan_info->cpi);
                                  request_ccb = scan_info->request_ccb;
                                  free(scan_info, M_TEMP);
                                  request_ccb->ccb_h.status = status;
                                  xpt_done(request_ccb);
                                  break;
                          }
                          xpt_setup_ccb(&request_ccb->ccb_h, path,
                              request_ccb->ccb_h.pinfo.priority);
                          request_ccb->ccb_h.func_code = XPT_SCAN_LUN;
                          request_ccb->ccb_h.cbfcnp = xpt_scan_bus;
                          request_ccb->ccb_h.ppriv_ptr0 = scan_info;
                          request_ccb->crcn.flags =
                              scan_info->request_ccb->crcn.flags;
                  } else {
                          status = xpt_create_path(&path, xpt_periph,
                              path_id, target_id, lun_id);
                          if (status != CAM_REQ_CMP) {
                                  printf("xpt_scan_bus: xpt_create_path failed "
                                         "with status %#x, halting LUN scan\n",
                                         status);
                                  goto hop_again;
                          }
                          xpt_setup_ccb(&request_ccb->ccb_h, path,
                                request_ccb->ccb_h.pinfo.priority);
                          request_ccb->ccb_h.func_code = XPT_SCAN_LUN;
                          request_ccb->ccb_h.cbfcnp = xpt_scan_bus;
                          request_ccb->ccb_h.ppriv_ptr0 = scan_info;
                          request_ccb->crcn.flags =
                                  scan_info->request_ccb->crcn.flags;
                  }
                  xpt_action(request_ccb);
                  break;
          }
          default:
                  break;
          }
  }
  
  typedef enum {
          PROBE_TUR,
          PROBE_INQUIRY,
          PROBE_FULL_INQUIRY,
          PROBE_MODE_SENSE,
          PROBE_SERIAL_NUM,
          PROBE_TUR_FOR_NEGOTIATION
  } probe_action;
  
  typedef enum {
          PROBE_INQUIRY_CKSUM     = 0x01,
          PROBE_SERIAL_CKSUM      = 0x02,
          PROBE_NO_ANNOUNCE       = 0x04
  } probe_flags;
  
  typedef struct {
          TAILQ_HEAD(, ccb_hdr) request_ccbs;
          probe_action    action;
          union ccb       saved_ccb;
          probe_flags     flags;
          MD5_CTX         context;
          u_int8_t        digest[16];
  } probe_softc;
  
  static void
  xpt_scan_lun(struct cam_periph *periph, struct cam_path *path,
               cam_flags flags, union ccb *request_ccb)
  {
          struct ccb_pathinq cpi;
          cam_status status;
          struct cam_path *new_path;
          struct cam_periph *old_periph;
          int s;
          
          CAM_DEBUG(request_ccb->ccb_h.path, CAM_DEBUG_TRACE,
                    ("xpt_scan_lun\n"));
          
          xpt_setup_ccb(&cpi.ccb_h, path, /*priority*/1);
          cpi.ccb_h.func_code = XPT_PATH_INQ;
          xpt_action((union ccb *)&cpi);
  
          if (cpi.ccb_h.status != CAM_REQ_CMP) {
                  if (request_ccb != NULL) {
                          request_ccb->ccb_h.status = cpi.ccb_h.status;
                          xpt_done(request_ccb);
                  }
                  return;
          }
  
          if ((cpi.hba_misc & PIM_NOINITIATOR) != 0) {
                  /*
                   * Can't scan the bus on an adapter that
                   * cannot perform the initiator role.
                   */
                  if (request_ccb != NULL) {
                          request_ccb->ccb_h.status = CAM_REQ_CMP;
                          xpt_done(request_ccb);
                  }
                  return;
          }
  
          if (request_ccb == NULL) {
                  request_ccb = malloc(sizeof(union ccb), M_TEMP, M_NOWAIT);
                  if (request_ccb == NULL) {
                          xpt_print_path(path);
                          printf("xpt_scan_lun: can't allocate CCB, can't "
                                 "continue\n");
                          return;
                  }
                  new_path = malloc(sizeof(*new_path), M_TEMP, M_NOWAIT);
                  if (new_path == NULL) {
                          xpt_print_path(path);
                          printf("xpt_scan_lun: can't allocate path, can't "
                                 "continue\n");
                          free(request_ccb, M_TEMP);
                          return;
                  }
                  status = xpt_compile_path(new_path, xpt_periph,
                                            path->bus->path_id,
                                            path->target->target_id,
                                            path->device->lun_id);
  
                  if (status != CAM_REQ_CMP) {
                          xpt_print_path(path);
                          printf("xpt_scan_lun: can't compile path, can't "
                                 "continue\n");
                          free(request_ccb, M_TEMP);
                          free(new_path, M_TEMP);
                          return;
                  }
                  xpt_setup_ccb(&request_ccb->ccb_h, new_path, /*priority*/ 1);
                  request_ccb->ccb_h.cbfcnp = xptscandone;
                  request_ccb->ccb_h.func_code = XPT_SCAN_LUN;
                  request_ccb->crcn.flags = flags;
          }
  
          s = splsoftcam();
          if ((old_periph = cam_periph_find(path, "probe")) != NULL) {
                  probe_softc *softc;
  
                  softc = (probe_softc *)old_periph->softc;
                  TAILQ_INSERT_TAIL(&softc->request_ccbs, &request_ccb->ccb_h,
                                    periph_links.tqe);
          } else {
                  status = cam_periph_alloc(proberegister, NULL, probecleanup,
                                            probestart, "probe",
                                            CAM_PERIPH_BIO,
                                            request_ccb->ccb_h.path, NULL, 0,
                                            request_ccb);
  
                  if (status != CAM_REQ_CMP) {
                          xpt_print_path(path);
                          printf("xpt_scan_lun: cam_alloc_periph returned an "
                                 "error, can't continue probe\n");
                          request_ccb->ccb_h.status = status;
                          xpt_done(request_ccb);
                  }
          }
          splx(s);
  }
  
  static void
  xptscandone(struct cam_periph *periph, union ccb *done_ccb)
  {
          xpt_release_path(done_ccb->ccb_h.path);
          free(done_ccb->ccb_h.path, M_TEMP);
          free(done_ccb, M_TEMP);
  }
  
  static cam_status
  proberegister(struct cam_periph *periph, void *arg)
  {
          union ccb *request_ccb; /* CCB representing the probe request */
          probe_softc *softc;
  
          request_ccb = (union ccb *)arg;
          if (periph == NULL) {
                  printf("proberegister: periph was NULL!!\n");
                  return(CAM_REQ_CMP_ERR);
          }
  
          if (request_ccb == NULL) {
                  printf("proberegister: no probe CCB, "
                         "can't register device\n");
                  return(CAM_REQ_CMP_ERR);
          }
  
          softc = (probe_softc *)malloc(sizeof(*softc), M_TEMP, M_NOWAIT);
  
          if (softc == NULL) {
                  printf("proberegister: Unable to probe new device. "
                         "Unable to allocate softc\n");                           
                  return(CAM_REQ_CMP_ERR);
          }
          TAILQ_INIT(&softc->request_ccbs);
          TAILQ_INSERT_TAIL(&softc->request_ccbs, &request_ccb->ccb_h,
                            periph_links.tqe);
          softc->flags = 0;
          periph->softc = softc;
          cam_periph_acquire(periph);
          /*
           * Ensure we've waited at least a bus settle
           * delay before attempting to probe the device.
           * For HBAs that don't do bus resets, this won't make a difference.
           */
          cam_periph_freeze_after_event(periph, &periph->path->bus->last_reset,
                                        SCSI_DELAY);
          probeschedule(periph);
          return(CAM_REQ_CMP);
  }
  
  static void
  probeschedule(struct cam_periph *periph)
  {
          struct ccb_pathinq cpi;
          union ccb *ccb;
          probe_softc *softc;
  
          softc = (probe_softc *)periph->softc;
          ccb = (union ccb *)TAILQ_FIRST(&softc->request_ccbs);
  
          xpt_setup_ccb(&cpi.ccb_h, periph->path, /*priority*/1);
          cpi.ccb_h.func_code = XPT_PATH_INQ;
          xpt_action((union ccb *)&cpi);
  
          /*
           * If a device has gone away and another device, or the same one,
           * is back in the same place, it should have a unit attention
           * condition pending.  It will not report the unit attention in
           * response to an inquiry, which may leave invalid transfer
           * negotiations in effect.  The TUR will reveal the unit attention
           * condition.  Only send the TUR for lun 0, since some devices 
           * will get confused by commands other than inquiry to non-existent
           * luns.  If you think a device has gone away start your scan from
           * lun 0.  This will insure that any bogus transfer settings are
           * invalidated.
           *
           * If we haven't seen the device before and the controller supports
           * some kind of transfer negotiation, negotiate with the first
           * sent command if no bus reset was performed at startup.  This
           * ensures that the device is not confused by transfer negotiation
           * settings left over by loader or BIOS action.
           */
          if (((ccb->ccb_h.path->device->flags & CAM_DEV_UNCONFIGURED) == 0)
           && (ccb->ccb_h.target_lun == 0)) {
                  softc->action = PROBE_TUR;
          } else if ((cpi.hba_inquiry & (PI_WIDE_32|PI_WIDE_16|PI_SDTR_ABLE)) != 0
                && (cpi.hba_misc & PIM_NOBUSRESET) != 0) {
                  proberequestdefaultnegotiation(periph);
                  softc->action = PROBE_INQUIRY;
          } else {
                  softc->action = PROBE_INQUIRY;
          }
  
          if (ccb->crcn.flags & CAM_EXPECT_INQ_CHANGE)
                  softc->flags |= PROBE_NO_ANNOUNCE;
          else
                  softc->flags &= ~PROBE_NO_ANNOUNCE;
  
          xpt_schedule(periph, ccb->ccb_h.pinfo.priority);
  }
  
  static void
  probestart(struct cam_periph *periph, union ccb *start_ccb)
  {
          /* Probe the device that our peripheral driver points to */
          struct ccb_scsiio *csio;
          probe_softc *softc;
  
          CAM_DEBUG(start_ccb->ccb_h.path, CAM_DEBUG_TRACE, ("probestart\n"));
  
          softc = (probe_softc *)periph->softc;
          csio = &start_ccb->csio;
  
          switch (softc->action) {
          case PROBE_TUR:
          case PROBE_TUR_FOR_NEGOTIATION:
          {
                  scsi_test_unit_ready(csio,
                                       /*retries*/4,
                                       probedone,
                                       MSG_SIMPLE_Q_TAG,
                                       SSD_FULL_SIZE,
                                       /*timeout*/60000);
                  break;
          }
          case PROBE_INQUIRY:
          case PROBE_FULL_INQUIRY:
          {
                  u_int inquiry_len;
                  struct scsi_inquiry_data *inq_buf;
  
                  inq_buf = &periph->path->device->inq_data;
                  /*
                   * If the device is currently configured, we calculate an
                   * MD5 checksum of the inquiry data, and if the serial number
                   * length is greater than 0, add the serial number data
                   * into the checksum as well.  Once the inquiry and the
                   * serial number check finish, we attempt to figure out
                   * whether we still have the same device.
                   */
                  if ((periph->path->device->flags & CAM_DEV_UNCONFIGURED) == 0) {
                          
                          MD5Init(&softc->context);
                          MD5Update(&softc->context, (unsigned char *)inq_buf,
                                    sizeof(struct scsi_inquiry_data));
                          softc->flags |= PROBE_INQUIRY_CKSUM;
                          if (periph->path->device->serial_num_len > 0) {
                                  MD5Update(&softc->context,
                                            periph->path->device->serial_num,
                                            periph->path->device->serial_num_len);
                                  softc->flags |= PROBE_SERIAL_CKSUM;
                          }
                          MD5Final(softc->digest, &softc->context);
                  } 
  
                  if (softc->action == PROBE_INQUIRY)
                          inquiry_len = SHORT_INQUIRY_LENGTH;
                  else
                          inquiry_len = inq_buf->additional_length + 5;
          
                  scsi_inquiry(csio,
                               /*retries*/4,
                               probedone,
                               MSG_SIMPLE_Q_TAG,
                               (u_int8_t *)inq_buf,
                               inquiry_len,
                               /*evpd*/FALSE,
                               /*page_code*/0,
                               SSD_MIN_SIZE,
                               /*timeout*/60 * 1000);
                  break;
          }
          case PROBE_MODE_SENSE:
          {
                  void  *mode_buf;
                  int    mode_buf_len;
  
                  mode_buf_len = sizeof(struct scsi_mode_header_6)
                               + sizeof(struct scsi_mode_blk_desc)
                               + sizeof(struct scsi_control_page);
                  mode_buf = malloc(mode_buf_len, M_TEMP, M_NOWAIT);
                  if (mode_buf != NULL) {
                          scsi_mode_sense(csio,
                                          /*retries*/4,
                                          probedone,
                                          MSG_SIMPLE_Q_TAG,
                                          /*dbd*/FALSE,
                                          SMS_PAGE_CTRL_CURRENT,
                                          SMS_CONTROL_MODE_PAGE,
                                          mode_buf,
                                          mode_buf_len,
                                          SSD_FULL_SIZE,
                                          /*timeout*/60000);
                          break;
                  }
                  xpt_print_path(periph->path);
                  printf("Unable to mode sense control page - malloc failure\n");
                  softc->action = PROBE_SERIAL_NUM;
                  /* FALLTHROUGH */
          }
          case PROBE_SERIAL_NUM:
          {
                  struct scsi_vpd_unit_serial_number *serial_buf;
                  struct cam_ed* device;
  
                  serial_buf = NULL;
                  device = periph->path->device;
                  device->serial_num = NULL;
                  device->serial_num_len = 0;
  
                  if ((device->quirk->quirks & CAM_QUIRK_NOSERIAL) == 0)
                          serial_buf = (struct scsi_vpd_unit_serial_number *)
                                  malloc(sizeof(*serial_buf), M_TEMP,
                                          M_NOWAIT | M_ZERO);
  
                  if (serial_buf != NULL) {
                          scsi_inquiry(csio,
                                       /*retries*/4,
                                       probedone,
                                       MSG_SIMPLE_Q_TAG,
                                       (u_int8_t *)serial_buf,
                                       sizeof(*serial_buf),
                                       /*evpd*/TRUE,
                                       SVPD_UNIT_SERIAL_NUMBER,
                                       SSD_MIN_SIZE,
                                       /*timeout*/60 * 1000);
                          break;
                  }
                  /*
                   * We'll have to do without, let our probedone
                   * routine finish up for us.
                   */
                  start_ccb->csio.data_ptr = NULL;
                  probedone(periph, start_ccb);
                  return;
          }
          }
          xpt_action(start_ccb);
  }
  
  static void
  proberequestdefaultnegotiation(struct cam_periph *periph)
  {
          struct ccb_trans_settings cts;
  
          xpt_setup_ccb(&cts.ccb_h, periph->path, /*priority*/1);
          cts.ccb_h.func_code = XPT_GET_TRAN_SETTINGS;
          cts.flags = CCB_TRANS_USER_SETTINGS;
          xpt_action((union ccb *)&cts);
          cts.ccb_h.func_code = XPT_SET_TRAN_SETTINGS;
          cts.flags &= ~CCB_TRANS_USER_SETTINGS;
          cts.flags |= CCB_TRANS_CURRENT_SETTINGS;
          xpt_action((union ccb *)&cts);
  }
  
  static void
  probedone(struct cam_periph *periph, union ccb *done_ccb)
  {
          probe_softc *softc;
          struct cam_path *path;
          u_int32_t  priority;
  
          CAM_DEBUG(done_ccb->ccb_h.path, CAM_DEBUG_TRACE, ("probedone\n"));
  
          softc = (probe_softc *)periph->softc;
          path = done_ccb->ccb_h.path;
          priority = done_ccb->ccb_h.pinfo.priority;
  
          switch (softc->action) {
          case PROBE_TUR:
          {
                  if ((done_ccb->ccb_h.status & CAM_STATUS_MASK) != CAM_REQ_CMP) {
  
                          if (cam_periph_error(done_ccb, 0,
                                               SF_NO_PRINT, NULL) == ERESTART)
                                  return;
                          else if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
                                  /* Don't wedge the queue */
                                  xpt_release_devq(done_ccb->ccb_h.path,
                                                   /*count*/1,
                                                   /*run_queue*/TRUE);
                  }
                  softc->action = PROBE_INQUIRY;
                  xpt_release_ccb(done_ccb);
                  xpt_schedule(periph, priority);
                  return;
          }
          case PROBE_INQUIRY:
          case PROBE_FULL_INQUIRY:
          {
                  if ((done_ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP) {
                          struct scsi_inquiry_data *inq_buf;
                          u_int8_t periph_qual;
  
                          path->device->flags |= CAM_DEV_INQUIRY_DATA_VALID;
                          inq_buf = &path->device->inq_data;
  
                          periph_qual = SID_QUAL(inq_buf);
                          
                          switch(periph_qual) {
                          case SID_QUAL_LU_CONNECTED:
                          {
                                  u_int8_t alen;
  
                                  /*
                                   * We conservatively request only
                                   * SHORT_INQUIRY_LEN bytes of inquiry
                                   * information during our first try
                                   * at sending an INQUIRY. If the device
                                   * has more information to give,
                                   * perform a second request specifying
                                   * the amount of information the device
                                   * is willing to give.
                                   */
                                  alen = inq_buf->additional_length;
                                  if (softc->action == PROBE_INQUIRY
                                   && alen > (SHORT_INQUIRY_LENGTH - 5)) {
                                          softc->action = PROBE_FULL_INQUIRY;
                                          xpt_release_ccb(done_ccb);
                                          xpt_schedule(periph, priority);
                                          return;
                                  }
  
                                  xpt_find_quirk(path->device);
  
                                  if ((inq_buf->flags & SID_CmdQue) != 0)
                                          softc->action = PROBE_MODE_SENSE;
                                  else
                                          softc->action = PROBE_SERIAL_NUM;
  
                                  path->device->flags &= ~CAM_DEV_UNCONFIGURED;
  
                                  xpt_release_ccb(done_ccb);
                                  xpt_schedule(periph, priority);
                                  return;
                          }
                          default:
                                  break;
                          }
                  } else if (cam_periph_error(done_ccb, 0,
                                              done_ccb->ccb_h.target_lun > 0
                                              ? SF_RETRY_UA|SF_QUIET_IR
                                              : SF_RETRY_UA,
                                              &softc->saved_ccb) == ERESTART) {
                          return;
                  } else if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
                          /* Don't wedge the queue */
                          xpt_release_devq(done_ccb->ccb_h.path, /*count*/1,
                                           /*run_queue*/TRUE);
                  }
                  /*
                   * If we get to this point, we got an error status back
                   * from the inquiry and the error status doesn't require
                   * automatically retrying the command.  Therefore, the
                   * inquiry failed.  If we had inquiry information before
                   * for this device, but this latest inquiry command failed,
                   * the device has probably gone away.  If this device isn't
                   * already marked unconfigured, notify the peripheral
                   * drivers that this device is no more.
                   */
                  if ((path->device->flags & CAM_DEV_UNCONFIGURED) == 0)
                          /* Send the async notification. */
                          xpt_async(AC_LOST_DEVICE, path, NULL);
  
                  xpt_release_ccb(done_ccb);
                  break;
          }
          case PROBE_MODE_SENSE:
          {
                  struct ccb_scsiio *csio;
                  struct scsi_mode_header_6 *mode_hdr;
  
                  csio = &done_ccb->csio;
                  mode_hdr = (struct scsi_mode_header_6 *)csio->data_ptr;
                  if ((csio->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP) {
                          struct scsi_control_page *page;
                          u_int8_t *offset;
  
                          offset = ((u_int8_t *)&mode_hdr[1])
                              + mode_hdr->blk_desc_len;
                          page = (struct scsi_control_page *)offset;
                          path->device->queue_flags = page->queue_flags;
                  } else if (cam_periph_error(done_ccb, 0,
                                              SF_RETRY_UA|SF_NO_PRINT,
                                              &softc->saved_ccb) == ERESTART) {
                          return;
                  } else if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
                          /* Don't wedge the queue */
                          xpt_release_devq(done_ccb->ccb_h.path,
                                           /*count*/1, /*run_queue*/TRUE);
                  }
                  xpt_release_ccb(done_ccb);
                  free(mode_hdr, M_TEMP);
                  softc->action = PROBE_SERIAL_NUM;
                  xpt_schedule(periph, priority);
                  return;
          }
          case PROBE_SERIAL_NUM:
          {
                  struct ccb_scsiio *csio;
                  struct scsi_vpd_unit_serial_number *serial_buf;
                  u_int32_t  priority;
                  int changed;
                  int have_serialnum;
  
                  changed = 1;
                  have_serialnum = 0;
                  csio = &done_ccb->csio;
                  priority = done_ccb->ccb_h.pinfo.priority;
                  serial_buf =
                      (struct scsi_vpd_unit_serial_number *)csio->data_ptr;
  
                  /* Clean up from previous instance of this device */
                  if (path->device->serial_num != NULL) {
                          free(path->device->serial_num, M_DEVBUF);
                          path->device->serial_num = NULL;
                          path->device->serial_num_len = 0;
                  }
  
                  if (serial_buf == NULL) {
                          /*
                           * Don't process the command as it was never sent
                           */
                  } else if ((csio->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP
                          && (serial_buf->length > 0)) {
  
                          have_serialnum = 1;
                          path->device->serial_num =
                                  (u_int8_t *)malloc((serial_buf->length + 1),
                                                     M_DEVBUF, M_NOWAIT);
                          if (path->device->serial_num != NULL) {
                                  bcopy(serial_buf->serial_num,
                                        path->device->serial_num,
                                        serial_buf->length);
                                  path->device->serial_num_len =
                                      serial_buf->length;
                                  path->device->serial_num[serial_buf->length]
                                      = '\0';
                          }
                  } else if (cam_periph_error(done_ccb, 0,
                                              SF_RETRY_UA|SF_NO_PRINT,
                                              &softc->saved_ccb) == ERESTART) {
                          return;
                  } else if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
                          /* Don't wedge the queue */
                          xpt_release_devq(done_ccb->ccb_h.path, /*count*/1,
                                           /*run_queue*/TRUE);
                  }
                  
                  /*
                   * Let's see if we have seen this device before.
                   */
                  if ((softc->flags & PROBE_INQUIRY_CKSUM) != 0) {
                          MD5_CTX context;
                          u_int8_t digest[16];
  
                          MD5Init(&context);
                          
                          MD5Update(&context,
                                    (unsigned char *)&path->device->inq_data,
                                    sizeof(struct scsi_inquiry_data));
  
                          if (have_serialnum)
                                  MD5Update(&context, serial_buf->serial_num,
                                            serial_buf->length);
  
                          MD5Final(digest, &context);
                          if (bcmp(softc->digest, digest, 16) == 0)
                                  changed = 0;
  
                          /*
                           * XXX Do we need to do a TUR in order to ensure
                           *     that the device really hasn't changed???
                           */
                          if ((changed != 0)
                           && ((softc->flags & PROBE_NO_ANNOUNCE) == 0))
                                  xpt_async(AC_LOST_DEVICE, path, NULL);
                  }
                  if (serial_buf != NULL)
                          free(serial_buf, M_TEMP);
  
                  if (changed != 0) {
                          /*
                           * Now that we have all the necessary
                           * information to safely perform transfer
                           * negotiations... Controllers don't perform
                           * any negotiation or tagged queuing until
                           * after the first XPT_SET_TRAN_SETTINGS ccb is
                           * received.  So, on a new device, just retreive
                           * the user settings, and set them as the current
                           * settings to set the device up.
                           */
                          proberequestdefaultnegotiation(periph);
                          xpt_release_ccb(done_ccb);
  
                          /*
                           * Perform a TUR to allow the controller to
                           * perform any necessary transfer negotiation.
                           */
                          softc->action = PROBE_TUR_FOR_NEGOTIATION;
                          xpt_schedule(periph, priority);
                          return;
                  }
                  xpt_release_ccb(done_ccb);
                  break;
          }
          case PROBE_TUR_FOR_NEGOTIATION:
                  if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
                          /* Don't wedge the queue */
                          xpt_release_devq(done_ccb->ccb_h.path, /*count*/1,
                                           /*run_queue*/TRUE);
                  }
  
                  path->device->flags &= ~CAM_DEV_UNCONFIGURED;
  
                  if ((softc->flags & PROBE_NO_ANNOUNCE) == 0) {
                          /* Inform the XPT that a new device has been found */
                          done_ccb->ccb_h.func_code = XPT_GDEV_TYPE;
                          xpt_action(done_ccb);
  
                          xpt_async(AC_FOUND_DEVICE, xpt_periph->path, done_ccb);
                  }
                  xpt_release_ccb(done_ccb);
                  break;
          }
          done_ccb = (union ccb *)TAILQ_FIRST(&softc->request_ccbs);
          TAILQ_REMOVE(&softc->request_ccbs, &done_ccb->ccb_h, periph_links.tqe);
          done_ccb->ccb_h.status = CAM_REQ_CMP;
          xpt_done(done_ccb);
          if (TAILQ_FIRST(&softc->request_ccbs) == NULL) {
                  cam_periph_invalidate(periph);
                  cam_periph_release(periph);
          } else {
                  probeschedule(periph);
          }
  }
  
  static void
  probecleanup(struct cam_periph *periph)
  {
          free(periph->softc, M_TEMP);
  }
  
  static void
  xpt_find_quirk(struct cam_ed *device)
  {
          caddr_t match;
  
          match = cam_quirkmatch((caddr_t)&device->inq_data,
                                 (caddr_t)xpt_quirk_table,
                                 sizeof(xpt_quirk_table)/sizeof(*xpt_quirk_table),
                                 sizeof(*xpt_quirk_table), scsi_inquiry_match);
  
          if (match == NULL)
                  panic("xpt_find_quirk: device didn't match wildcard entry!!");
  
          device->quirk = (struct xpt_quirk_entry *)match;
  }
  
  static void
  xpt_set_transfer_settings(struct ccb_trans_settings *cts, struct cam_ed *device,
                            int async_update)
  {
          struct  cam_sim *sim;
          int     qfrozen;
  
          sim = cts->ccb_h.path->bus->sim;
          if (async_update == FALSE) {
                  struct  scsi_inquiry_data *inq_data;
                  struct  ccb_pathinq cpi;
                  struct  ccb_trans_settings cur_cts;
  
                  if (device == NULL) {
                          cts->ccb_h.status = CAM_PATH_INVALID;
                          xpt_done((union ccb *)cts);
                          return;
                  }
  
                  /*
                   * Perform sanity checking against what the
                   * controller and device can do.
                   */
                  xpt_setup_ccb(&cpi.ccb_h, cts->ccb_h.path, /*priority*/1);
                  cpi.ccb_h.func_code = XPT_PATH_INQ;
                  xpt_action((union ccb *)&cpi);
                  xpt_setup_ccb(&cur_cts.ccb_h, cts->ccb_h.path, /*priority*/1);
                  cur_cts.ccb_h.func_code = XPT_GET_TRAN_SETTINGS;
                  cur_cts.flags = CCB_TRANS_CURRENT_SETTINGS;
                  xpt_action((union ccb *)&cur_cts);
                  inq_data = &device->inq_data;
  
                  /* Fill in any gaps in what the user gave us */
                  if ((cts->valid & CCB_TRANS_SYNC_RATE_VALID) == 0)
                          cts->sync_period = cur_cts.sync_period;
                  if ((cts->valid & CCB_TRANS_SYNC_OFFSET_VALID) == 0)
                          cts->sync_offset = cur_cts.sync_offset;
                  if ((cts->valid & CCB_TRANS_BUS_WIDTH_VALID) == 0)
                          cts->bus_width = cur_cts.bus_width;
                  if ((cts->valid & CCB_TRANS_DISC_VALID) == 0) {
                          cts->flags &= ~CCB_TRANS_DISC_ENB;
                          cts->flags |= cur_cts.flags & CCB_TRANS_DISC_ENB;
                  }
                  if ((cts->valid & CCB_TRANS_TQ_VALID) == 0) {
                          cts->flags &= ~CCB_TRANS_TAG_ENB;
                          cts->flags |= cur_cts.flags & CCB_TRANS_TAG_ENB;
                  }
  
                  if (((device->flags & CAM_DEV_INQUIRY_DATA_VALID) != 0
                    && (inq_data->flags & SID_Sync) == 0)
                   || ((cpi.hba_inquiry & PI_SDTR_ABLE) == 0)
                   || (cts->sync_offset == 0)
                   || (cts->sync_period == 0)) {
                          /* Force async */
                          cts->sync_period = 0;
                          cts->sync_offset = 0;
                  } else if ((device->flags & CAM_DEV_INQUIRY_DATA_VALID) != 0) {
  
                          if ((inq_data->spi3data & SID_SPI_CLOCK_DT) == 0
                           && cts->sync_period <= 0x9) {
                                  /*
                                   * Don't allow DT transmission rates if the
                                   * device does not support it.
                                   */
                                  cts->sync_period = 0xa;
                          }
                          if ((inq_data->spi3data & SID_SPI_IUS) == 0
                           && cts->sync_period <= 0x8) {
                                  /*
                                   * Don't allow PACE transmission rates
                                   * if the device does support packetized
                                   * transfers.
                                   */
                                  cts->sync_period = 0x9;
                          }
                  }
  
                  switch (cts->bus_width) {
                  case MSG_EXT_WDTR_BUS_32_BIT:
                          if (((device->flags & CAM_DEV_INQUIRY_DATA_VALID) == 0
                            || (inq_data->flags & SID_WBus32) != 0)
                           && (cpi.hba_inquiry & PI_WIDE_32) != 0)
                                  break;
                          /* Fall Through to 16-bit */
                  case MSG_EXT_WDTR_BUS_16_BIT:
                          if (((device->flags & CAM_DEV_INQUIRY_DATA_VALID) == 0
                            || (inq_data->flags & SID_WBus16) != 0)
                           && (cpi.hba_inquiry & PI_WIDE_16) != 0) {
                                  cts->bus_width = MSG_EXT_WDTR_BUS_16_BIT;
                                  break;
                          }
                          /* Fall Through to 8-bit */
                  default: /* New bus width?? */
                  case MSG_EXT_WDTR_BUS_8_BIT:
                          /* All targets can do this */
                          cts->bus_width = MSG_EXT_WDTR_BUS_8_BIT;
                          break;
                  }
  
                  if ((cts->flags & CCB_TRANS_DISC_ENB) == 0) {
                          /*
                           * Can't tag queue without disconnection.
                           */
                          cts->flags &= ~CCB_TRANS_TAG_ENB;
                          cts->valid |= CCB_TRANS_TQ_VALID;
                  }
  
                  if ((cpi.hba_inquiry & PI_TAG_ABLE) == 0
                   || (inq_data->flags & SID_CmdQue) == 0
                   || (device->queue_flags & SCP_QUEUE_DQUE) != 0
                   || (device->quirk->mintags == 0)) {
                          /*
                           * Can't tag on hardware that doesn't support,
                           * doesn't have it enabled, or has broken tag support.
                           */
                          cts->flags &= ~CCB_TRANS_TAG_ENB;
                  }
          }
  
          qfrozen = FALSE;
          if ((cts->valid & CCB_TRANS_TQ_VALID) != 0) {
                  int device_tagenb;
  
                  /*
                   * If we are transitioning from tags to no-tags or
                   * vice-versa, we need to carefully freeze and restart
                   * the queue so that we don't overlap tagged and non-tagged
                   * commands.  We also temporarily stop tags if there is
                   * a change in transfer negotiation settings to allow
                   * "tag-less" negotiation.
                   */
                  if ((device->flags & CAM_DEV_TAG_AFTER_COUNT) != 0
                   || (device->inq_flags & SID_CmdQue) != 0)
                          device_tagenb = TRUE;
                  else
                          device_tagenb = FALSE;
  
                  if (((cts->flags & CCB_TRANS_TAG_ENB) != 0
                    && device_tagenb == FALSE)
                   || ((cts->flags & CCB_TRANS_TAG_ENB) == 0
                    && device_tagenb == TRUE)) {
  
                          if ((cts->flags & CCB_TRANS_TAG_ENB) != 0) {
                                  /*
                                   * Delay change to use tags until after a
                                   * few commands have gone to this device so
                                   * the controller has time to perform transfer
                                   * negotiations without tagged messages getting
                                   * in the way.
                                   */
                                  device->tag_delay_count = CAM_TAG_DELAY_COUNT;
                                  device->flags |= CAM_DEV_TAG_AFTER_COUNT;
                          } else {
                                  xpt_freeze_devq(cts->ccb_h.path, /*count*/1);
                                  qfrozen = TRUE;
                                  device->inq_flags &= ~SID_CmdQue;
                                  xpt_dev_ccbq_resize(cts->ccb_h.path,
                                                      sim->max_dev_openings);
                                  device->flags &= ~CAM_DEV_TAG_AFTER_COUNT;
                                  device->tag_delay_count = 0;
                          }
                  }
          }
  
          if (async_update == FALSE) {
                  /*
                   * If we are currently performing tagged transactions to
                   * this device and want to change its negotiation parameters,
                   * go non-tagged for a bit to give the controller a chance to
                   * negotiate unhampered by tag messages.
                   */
                  if ((device->inq_flags & SID_CmdQue) != 0
                   && (cts->flags & (CCB_TRANS_SYNC_RATE_VALID|
                                     CCB_TRANS_SYNC_OFFSET_VALID|
                                     CCB_TRANS_BUS_WIDTH_VALID)) != 0)
                          xpt_toggle_tags(cts->ccb_h.path);
  
                  (*(sim->sim_action))(sim, (union ccb *)cts);
          }
  
          if (qfrozen) {
                  struct ccb_relsim crs;
  
                  xpt_setup_ccb(&crs.ccb_h, cts->ccb_h.path,
                                /*priority*/1);
                  crs.ccb_h.func_code = XPT_REL_SIMQ;
                  crs.release_flags = RELSIM_RELEASE_AFTER_QEMPTY;
                  crs.openings
                      = crs.release_timeout 
                      = crs.qfrozen_cnt
                      = 0;
                  xpt_action((union ccb *)&crs);
          }
  }
  
  static void
  xpt_toggle_tags(struct cam_path *path)
  {
          struct cam_ed *dev;
  
          /*
           * Give controllers a chance to renegotiate
           * before starting tag operations.  We
           * "toggle" tagged queuing off then on
           * which causes the tag enable command delay
           * counter to come into effect.
           */
          dev = path->device;
          if ((dev->flags & CAM_DEV_TAG_AFTER_COUNT) != 0
           || ((dev->inq_flags & SID_CmdQue) != 0
            && (dev->inq_flags & (SID_Sync|SID_WBus16|SID_WBus32)) != 0)) {
                  struct ccb_trans_settings cts;
  
                  xpt_setup_ccb(&cts.ccb_h, path, 1);
                  cts.flags = 0;
                  cts.valid = CCB_TRANS_TQ_VALID;
                  xpt_set_transfer_settings(&cts, path->device,
                                            /*async_update*/TRUE);
                  cts.flags = CCB_TRANS_TAG_ENB;
                  xpt_set_transfer_settings(&cts, path->device,
                                            /*async_update*/TRUE);
          }
  }
  
  static void
  xpt_start_tags(struct cam_path *path)
  {
          struct ccb_relsim crs;
          struct cam_ed *device;
          struct cam_sim *sim;
          int    newopenings;
  
          device = path->device;
          sim = path->bus->sim;
          device->flags &= ~CAM_DEV_TAG_AFTER_COUNT;
          xpt_freeze_devq(path, /*count*/1);
          device->inq_flags |= SID_CmdQue;
          newopenings = min(device->quirk->maxtags, sim->max_tagged_dev_openings);
          xpt_dev_ccbq_resize(path, newopenings);
          xpt_setup_ccb(&crs.ccb_h, path, /*priority*/1);
          crs.ccb_h.func_code = XPT_REL_SIMQ;
          crs.release_flags = RELSIM_RELEASE_AFTER_QEMPTY;
          crs.openings
              = crs.release_timeout 
              = crs.qfrozen_cnt
              = 0;
          xpt_action((union ccb *)&crs);
  }
  
  static int busses_to_config;
  static int busses_to_reset;
  
  static int
  xptconfigbuscountfunc(struct cam_eb *bus, void *arg)
  {
          if (bus->path_id != CAM_XPT_PATH_ID) {
                  struct cam_path path;
                  struct ccb_pathinq cpi;
                  int can_negotiate;
  
                  busses_to_config++;
                  xpt_compile_path(&path, NULL, bus->path_id,
                                   CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD);
                  xpt_setup_ccb(&cpi.ccb_h, &path, /*priority*/1);
                  cpi.ccb_h.func_code = XPT_PATH_INQ;
                  xpt_action((union ccb *)&cpi);
                  can_negotiate = cpi.hba_inquiry;
                  can_negotiate &= (PI_WIDE_32|PI_WIDE_16|PI_SDTR_ABLE);
                  if ((cpi.hba_misc & PIM_NOBUSRESET) == 0
                   && can_negotiate)
                          busses_to_reset++;
                  xpt_release_path(&path);
          }
  
          return(1);
  }
  
  static int
  xptconfigfunc(struct cam_eb *bus, void *arg)
  {
          struct  cam_path *path;
          union   ccb *work_ccb;
  
          if (bus->path_id != CAM_XPT_PATH_ID) {
                  cam_status status;
                  int can_negotiate;
  
                  work_ccb = xpt_alloc_ccb();
                  if ((status = xpt_create_path(&path, xpt_periph, bus->path_id,
                                                CAM_TARGET_WILDCARD,
                                                CAM_LUN_WILDCARD)) !=CAM_REQ_CMP){
                          printf("xptconfigfunc: xpt_create_path failed with "
                                 "status %#x for bus %d\n", status, bus->path_id);
                          printf("xptconfigfunc: halting bus configuration\n");
                          xpt_free_ccb(work_ccb);
                          busses_to_config--;
                          xpt_finishconfig(xpt_periph, NULL);
                          return(0);
                  }
                  xpt_setup_ccb(&work_ccb->ccb_h, path, /*priority*/1);
                  work_ccb->ccb_h.func_code = XPT_PATH_INQ;
                  xpt_action(work_ccb);
                  if (work_ccb->ccb_h.status != CAM_REQ_CMP) {
                          printf("xptconfigfunc: CPI failed on bus %d "
                                 "with status %d\n", bus->path_id,
                                 work_ccb->ccb_h.status);
                          xpt_finishconfig(xpt_periph, work_ccb);
                          return(1);
                  }
  
                  can_negotiate = work_ccb->cpi.hba_inquiry;
                  can_negotiate &= (PI_WIDE_32|PI_WIDE_16|PI_SDTR_ABLE);
                  if ((work_ccb->cpi.hba_misc & PIM_NOBUSRESET) == 0
                   && (can_negotiate != 0)) {
                          xpt_setup_ccb(&work_ccb->ccb_h, path, /*priority*/1);
                          work_ccb->ccb_h.func_code = XPT_RESET_BUS;
                          work_ccb->ccb_h.cbfcnp = NULL;
                          CAM_DEBUG(path, CAM_DEBUG_SUBTRACE,
                                    ("Resetting Bus\n"));
                          xpt_action(work_ccb);
                          xpt_finishconfig(xpt_periph, work_ccb);
                  } else {
                          /* Act as though we performed a successful BUS RESET */
                          work_ccb->ccb_h.func_code = XPT_RESET_BUS;
                          xpt_finishconfig(xpt_periph, work_ccb);
                  }
          }
  
          return(1);
  }
  
  static void
  xpt_config(void *arg)
  {
          /* Now that interrupts are enabled, go find our devices */
  
  #ifdef CAMDEBUG
          /* Setup debugging flags and path */
  #ifdef CAM_DEBUG_FLAGS
          cam_dflags = CAM_DEBUG_FLAGS;
  #else /* !CAM_DEBUG_FLAGS */
          cam_dflags = CAM_DEBUG_NONE;
  #endif /* CAM_DEBUG_FLAGS */
  #ifdef CAM_DEBUG_BUS
          if (cam_dflags != CAM_DEBUG_NONE) {
                  if (xpt_create_path(&cam_dpath, xpt_periph,
                                      CAM_DEBUG_BUS, CAM_DEBUG_TARGET,
                                      CAM_DEBUG_LUN) != CAM_REQ_CMP) {
                          printf("xpt_config: xpt_create_path() failed for debug"
                                 " target %d:%d:%d, debugging disabled\n",
                                 CAM_DEBUG_BUS, CAM_DEBUG_TARGET, CAM_DEBUG_LUN);
                          cam_dflags = CAM_DEBUG_NONE;
                  }
          } else
                  cam_dpath = NULL;
  #else /* !CAM_DEBUG_BUS */
          cam_dpath = NULL;
  #endif /* CAM_DEBUG_BUS */
  #endif /* CAMDEBUG */
  
          /*
           * Scan all installed busses.
           */
          xpt_for_all_busses(xptconfigbuscountfunc, NULL);
  
          if (busses_to_config == 0) {
                  /* Call manually because we don't have any busses */
                  xpt_finishconfig(xpt_periph, NULL);
          } else  {
                  if (busses_to_reset > 0 && SCSI_DELAY >= 2000) {
                          printf("Waiting %d seconds for SCSI "
                                 "devices to settle\n", SCSI_DELAY/1000);
                  }
                  xpt_for_all_busses(xptconfigfunc, NULL);
          }
  }
  
  /*
   * If the given device only has one peripheral attached to it, and if that
   * peripheral is the passthrough driver, announce it.  This insures that the
   * user sees some sort of announcement for every peripheral in their system.
   */
  static int
  xptpassannouncefunc(struct cam_ed *device, void *arg)
  {
          struct cam_periph *periph;
          int i;
  
          for (periph = SLIST_FIRST(&device->periphs), i = 0; periph != NULL;
               periph = SLIST_NEXT(periph, periph_links), i++);
  
          periph = SLIST_FIRST(&device->periphs);
          if ((i == 1)
           && (strncmp(periph->periph_name, "pass", 4) == 0))
                  xpt_announce_periph(periph, NULL);
  
          return(1);
  }
  
  static void
  xpt_finishconfig(struct cam_periph *periph, union ccb *done_ccb)
  {
          struct  periph_driver **p_drv;
          int     i;
  
          if (done_ccb != NULL) {
                  CAM_DEBUG(done_ccb->ccb_h.path, CAM_DEBUG_TRACE,
                            ("xpt_finishconfig\n"));
                  switch(done_ccb->ccb_h.func_code) {
                  case XPT_RESET_BUS:
                          if (done_ccb->ccb_h.status == CAM_REQ_CMP) {
                                  done_ccb->ccb_h.func_code = XPT_SCAN_BUS;
                                  done_ccb->ccb_h.cbfcnp = xpt_finishconfig;
                                  xpt_action(done_ccb);
                                  return;
                          }
                          /* FALLTHROUGH */
                  case XPT_SCAN_BUS:
                  default:
                          xpt_free_path(done_ccb->ccb_h.path);
                          busses_to_config--;
                          break;
                  }
          }
  
          if (busses_to_config == 0) {
                  /* Register all the peripheral drivers */
                  /* XXX This will have to change when we have loadable modules */
                  p_drv = (struct periph_driver **)periphdriver_set.ls_items;
                  for (i = 0; p_drv[i] != NULL; i++) {
                          (*p_drv[i]->init)();
                  }
  
                  /*
                   * Check for devices with no "standard" peripheral driver
                   * attached.  For any devices like that, announce the
                   * passthrough driver so the user will see something.
                   */
                  xpt_for_all_devices(xptpassannouncefunc, NULL);
  
                  /* Release our hook so that the boot can continue. */
                  config_intrhook_disestablish(xpt_config_hook);
                  free(xpt_config_hook, M_TEMP);
                  xpt_config_hook = NULL;
          }
          if (done_ccb != NULL)
                  xpt_free_ccb(done_ccb);
  }
  
  static void
  xptaction(struct cam_sim *sim, union ccb *work_ccb)
  {
          CAM_DEBUG(work_ccb->ccb_h.path, CAM_DEBUG_TRACE, ("xptaction\n"));
  
          switch (work_ccb->ccb_h.func_code) {
          /* Common cases first */
          case XPT_PATH_INQ:              /* Path routing inquiry */
          {
                  struct ccb_pathinq *cpi;
  
                  cpi = &work_ccb->cpi;
                  cpi->version_num = 1; /* XXX??? */
                  cpi->hba_inquiry = 0;
                  cpi->target_sprt = 0;
                  cpi->hba_misc = 0;
                  cpi->hba_eng_cnt = 0;
                  cpi->max_target = 0;
                  cpi->max_lun = 0;
                  cpi->initiator_id = 0;
                  strncpy(cpi->sim_vid, "FreeBSD", SIM_IDLEN);
                  strncpy(cpi->hba_vid, "", HBA_IDLEN);
                  strncpy(cpi->dev_name, sim->sim_name, DEV_IDLEN);
                  cpi->unit_number = sim->unit_number;
                  cpi->bus_id = sim->bus_id;
                  cpi->base_transfer_speed = 0;
                  cpi->ccb_h.status = CAM_REQ_CMP;
                  xpt_done(work_ccb);
                  break;
          }
          default:
                  work_ccb->ccb_h.status = CAM_REQ_INVALID;
                  xpt_done(work_ccb);
                  break;
          }
  }
  
  /*
   * The xpt as a "controller" has no interrupt sources, so polling
   * is a no-op.
   */
  static void
  xptpoll(struct cam_sim *sim)
  {
  }
  
  /*
   * Should only be called by the machine interrupt dispatch routines,
   * so put these prototypes here instead of in the header.
   */
  
  static void
  swi_camnet(void)
  {
          camisr(&cam_netq);
  }
  
  static void
  swi_cambio(void)
  {
          camisr(&cam_bioq);
  }
  
  static void
  camisr(cam_isrq_t *queue)
  {
          int     s;
          struct  ccb_hdr *ccb_h;
  
          s = splcam();
          while ((ccb_h = TAILQ_FIRST(queue)) != NULL) {
                  int     runq;
  
                  TAILQ_REMOVE(queue, ccb_h, sim_links.tqe);
                  ccb_h->pinfo.index = CAM_UNQUEUED_INDEX;
                  splx(s);
  
                  CAM_DEBUG(ccb_h->path, CAM_DEBUG_TRACE,
                            ("camisr\n"));
  
                  runq = FALSE;
  
                  if (ccb_h->flags & CAM_HIGH_POWER) {
                          struct highpowerlist    *hphead;
                          struct cam_ed           *device;
                          union ccb               *send_ccb;
  
                          hphead = &highpowerq;
  
                          send_ccb = (union ccb *)STAILQ_FIRST(hphead);
  
                          /*
                           * Increment the count since this command is done.
                           */
                          num_highpower++;
  
                          /* 
                           * Any high powered commands queued up?
                           */
                          if (send_ccb != NULL) {
                                  device = send_ccb->ccb_h.path->device;
  
                                  STAILQ_REMOVE_HEAD(hphead, xpt_links.stqe);
  
                                  xpt_release_devq(send_ccb->ccb_h.path,
                                                   /*count*/1, /*runqueue*/TRUE);
                          }
                  }
                  if ((ccb_h->func_code & XPT_FC_USER_CCB) == 0) {
                          struct cam_ed *dev;
  
                          dev = ccb_h->path->device;
  
                          s = splcam();
                          cam_ccbq_ccb_done(&dev->ccbq, (union ccb *)ccb_h);
  
                          ccb_h->path->bus->sim->devq->send_active--;
                          ccb_h->path->bus->sim->devq->send_openings++;
                          splx(s);
                          
                          if ((dev->flags & CAM_DEV_REL_ON_COMPLETE) != 0
                           || ((dev->flags & CAM_DEV_REL_ON_QUEUE_EMPTY) != 0
                            && (dev->ccbq.dev_active == 0))) {
                                  
                                  xpt_release_devq(ccb_h->path, /*count*/1,
                                                   /*run_queue*/TRUE);
                          }
  
                          if ((dev->flags & CAM_DEV_TAG_AFTER_COUNT) != 0
                           && (--dev->tag_delay_count == 0))
                                  xpt_start_tags(ccb_h->path);
  
                          if ((dev->ccbq.queue.entries > 0)
                           && (dev->qfrozen_cnt == 0)
                           && (device_is_send_queued(dev) == 0)) {
                                  runq = xpt_schedule_dev_sendq(ccb_h->path->bus,
                                                                dev);
                          }
                  }
  
                  if (ccb_h->status & CAM_RELEASE_SIMQ) {
                          xpt_release_simq(ccb_h->path->bus->sim,
                                           /*run_queue*/TRUE);
                          ccb_h->status &= ~CAM_RELEASE_SIMQ;
                          runq = FALSE;
                  } 
  
                  if ((ccb_h->flags & CAM_DEV_QFRZDIS)
                   && (ccb_h->status & CAM_DEV_QFRZN)) {
                          xpt_release_devq(ccb_h->path, /*count*/1,
                                           /*run_queue*/TRUE);
                          ccb_h->status &= ~CAM_DEV_QFRZN;
                  } else if (runq) {
                          xpt_run_dev_sendq(ccb_h->path->bus);
                  }
  
                  /* Call the peripheral driver's callback */
                  (*ccb_h->cbfcnp)(ccb_h->path->periph, (union ccb *)ccb_h);
  
                  /* Raise IPL for while test */
                  s = splcam();
          }
          splx(s);
  }