FreeBSD/Linux Kernel Cross Reference
sys/dev/acpica/acpi_cpu.c

     /*-
      * Copyright (c) 2003-2005 Nate Lawson (SDG)
      * Copyright (c) 2001 Michael Smith
      * 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.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.2/sys/dev/acpica/acpi_cpu.c 283892 2015-06-01 19:26:24Z jkim $");
    
    #include "opt_acpi.h"
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/cpu.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/pcpu.h>
    #include <sys/power.h>
    #include <sys/proc.h>
    #include <sys/sched.h>
    #include <sys/sbuf.h>
    #include <sys/smp.h>
    
    #include <dev/pci/pcivar.h>
    #include <machine/atomic.h>
    #include <machine/bus.h>
    #if defined(__amd64__) || defined(__i386__)
    #include <machine/clock.h>
    #endif
    #include <sys/rman.h>
    
    #include <contrib/dev/acpica/include/acpi.h>
    #include <contrib/dev/acpica/include/accommon.h>
    
    #include <dev/acpica/acpivar.h>
    
    /*
     * Support for ACPI Processor devices, including C[1-3] sleep states.
     */
    
    /* Hooks for the ACPI CA debugging infrastructure */
    #define _COMPONENT      ACPI_PROCESSOR
    ACPI_MODULE_NAME("PROCESSOR")
    
    struct acpi_cx {
        struct resource     *p_lvlx;        /* Register to read to enter state. */
        uint32_t             type;          /* C1-3 (C4 and up treated as C3). */
        uint32_t             trans_lat;     /* Transition latency (usec). */
        uint32_t             power;         /* Power consumed (mW). */
        int                  res_type;      /* Resource type for p_lvlx. */
        int                  res_rid;       /* Resource ID for p_lvlx. */
    };
    #define MAX_CX_STATES    8
    
    struct acpi_cpu_softc {
        device_t             cpu_dev;
        ACPI_HANDLE          cpu_handle;
        struct pcpu         *cpu_pcpu;
        uint32_t             cpu_acpi_id;   /* ACPI processor id */
        uint32_t             cpu_p_blk;     /* ACPI P_BLK location */
        uint32_t             cpu_p_blk_len; /* P_BLK length (must be 6). */
        struct acpi_cx       cpu_cx_states[MAX_CX_STATES];
        int                  cpu_cx_count;  /* Number of valid Cx states. */
        int                  cpu_prev_sleep;/* Last idle sleep duration. */
        int                  cpu_features;  /* Child driver supported features. */
        /* Runtime state. */
        int                  cpu_non_c2;    /* Index of lowest non-C2 state. */
        int                  cpu_non_c3;    /* Index of lowest non-C3 state. */
        u_int                cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */
        /* Values for sysctl. */
        struct sysctl_ctx_list cpu_sysctl_ctx;
        struct sysctl_oid   *cpu_sysctl_tree;
        int                  cpu_cx_lowest;
        int                  cpu_cx_lowest_lim;
        int                  cpu_disable_idle; /* Disable entry to idle function */
        char                 cpu_cx_supported[64];
    };
    
   struct acpi_cpu_device {
       struct resource_list        ad_rl;
   };
   
   #define CPU_GET_REG(reg, width)                                         \
       (bus_space_read_ ## width(rman_get_bustag((reg)),                   \
                         rman_get_bushandle((reg)), 0))
   #define CPU_SET_REG(reg, width, val)                                    \
       (bus_space_write_ ## width(rman_get_bustag((reg)),                  \
                          rman_get_bushandle((reg)), 0, (val)))
   
   #define PM_USEC(x)       ((x) >> 2)     /* ~4 clocks per usec (3.57955 Mhz) */
   
   #define ACPI_NOTIFY_CX_STATES   0x81    /* _CST changed. */
   
   #define CPU_QUIRK_NO_C3         (1<<0)  /* C3-type states are not usable. */
   #define CPU_QUIRK_NO_BM_CTRL    (1<<2)  /* No bus mastering control. */
   
   #define PCI_VENDOR_INTEL        0x8086
   #define PCI_DEVICE_82371AB_3    0x7113  /* PIIX4 chipset for quirks. */
   #define PCI_REVISION_A_STEP     0
   #define PCI_REVISION_B_STEP     1
   #define PCI_REVISION_4E         2
   #define PCI_REVISION_4M         3
   #define PIIX4_DEVACTB_REG       0x58
   #define PIIX4_BRLD_EN_IRQ0      (1<<0)
   #define PIIX4_BRLD_EN_IRQ       (1<<1)
   #define PIIX4_BRLD_EN_IRQ8      (1<<5)
   #define PIIX4_STOP_BREAK_MASK   (PIIX4_BRLD_EN_IRQ0 | PIIX4_BRLD_EN_IRQ | PIIX4_BRLD_EN_IRQ8)
   #define PIIX4_PCNTRL_BST_EN     (1<<10)
   
   /* Allow users to ignore processor orders in MADT. */
   static int cpu_unordered;
   TUNABLE_INT("debug.acpi.cpu_unordered", &cpu_unordered);
   SYSCTL_INT(_debug_acpi, OID_AUTO, cpu_unordered, CTLFLAG_RDTUN,
       &cpu_unordered, 0,
       "Do not use the MADT to match ACPI Processor objects to CPUs.");
   
   /* Platform hardware resource information. */
   static uint32_t          cpu_smi_cmd;   /* Value to write to SMI_CMD. */
   static uint8_t           cpu_cst_cnt;   /* Indicate we are _CST aware. */
   static int               cpu_quirks;    /* Indicate any hardware bugs. */
   
   /* Values for sysctl. */
   static struct sysctl_ctx_list cpu_sysctl_ctx;
   static struct sysctl_oid *cpu_sysctl_tree;
   static int               cpu_cx_generic;
   static int               cpu_cx_lowest_lim;
   
   static device_t         *cpu_devices;
   static int               cpu_ndevices;
   static struct acpi_cpu_softc **cpu_softc;
   ACPI_SERIAL_DECL(cpu, "ACPI CPU");
   
   static int      acpi_cpu_probe(device_t dev);
   static int      acpi_cpu_attach(device_t dev);
   static int      acpi_cpu_suspend(device_t dev);
   static int      acpi_cpu_resume(device_t dev);
   static int      acpi_pcpu_get_id(device_t dev, uint32_t *acpi_id,
                       uint32_t *cpu_id);
   static struct resource_list *acpi_cpu_get_rlist(device_t dev, device_t child);
   static device_t acpi_cpu_add_child(device_t dev, u_int order, const char *name,
                       int unit);
   static int      acpi_cpu_read_ivar(device_t dev, device_t child, int index,
                       uintptr_t *result);
   static int      acpi_cpu_shutdown(device_t dev);
   static void     acpi_cpu_cx_probe(struct acpi_cpu_softc *sc);
   static void     acpi_cpu_generic_cx_probe(struct acpi_cpu_softc *sc);
   static int      acpi_cpu_cx_cst(struct acpi_cpu_softc *sc);
   static void     acpi_cpu_startup(void *arg);
   static void     acpi_cpu_startup_cx(struct acpi_cpu_softc *sc);
   static void     acpi_cpu_cx_list(struct acpi_cpu_softc *sc);
   static void     acpi_cpu_idle(sbintime_t sbt);
   static void     acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context);
   static void     acpi_cpu_quirks(void);
   static void     acpi_cpu_quirks_piix4(void);
   static int      acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS);
   static int      acpi_cpu_set_cx_lowest(struct acpi_cpu_softc *sc);
   static int      acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);
   static int      acpi_cpu_global_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);
   
   static device_method_t acpi_cpu_methods[] = {
       /* Device interface */
       DEVMETHOD(device_probe,     acpi_cpu_probe),
       DEVMETHOD(device_attach,    acpi_cpu_attach),
       DEVMETHOD(device_detach,    bus_generic_detach),
       DEVMETHOD(device_shutdown,  acpi_cpu_shutdown),
       DEVMETHOD(device_suspend,   acpi_cpu_suspend),
       DEVMETHOD(device_resume,    acpi_cpu_resume),
   
       /* Bus interface */
       DEVMETHOD(bus_add_child,    acpi_cpu_add_child),
       DEVMETHOD(bus_read_ivar,    acpi_cpu_read_ivar),
       DEVMETHOD(bus_get_resource_list, acpi_cpu_get_rlist),
       DEVMETHOD(bus_get_resource, bus_generic_rl_get_resource),
       DEVMETHOD(bus_set_resource, bus_generic_rl_set_resource),
       DEVMETHOD(bus_alloc_resource, bus_generic_rl_alloc_resource),
       DEVMETHOD(bus_release_resource, bus_generic_rl_release_resource),
       DEVMETHOD(bus_activate_resource, bus_generic_activate_resource),
       DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource),
       DEVMETHOD(bus_setup_intr,   bus_generic_setup_intr),
       DEVMETHOD(bus_teardown_intr, bus_generic_teardown_intr),
   
       DEVMETHOD_END
   };
   
   static driver_t acpi_cpu_driver = {
       "cpu",
       acpi_cpu_methods,
       sizeof(struct acpi_cpu_softc),
   };
   
   static devclass_t acpi_cpu_devclass;
   DRIVER_MODULE(cpu, acpi, acpi_cpu_driver, acpi_cpu_devclass, 0, 0);
   MODULE_DEPEND(cpu, acpi, 1, 1, 1);
   
   static int
   acpi_cpu_probe(device_t dev)
   {
       int                    acpi_id, cpu_id;
       ACPI_BUFFER            buf;
       ACPI_HANDLE            handle;
       ACPI_OBJECT            *obj;
       ACPI_STATUS            status;
   
       if (acpi_disabled("cpu") || acpi_get_type(dev) != ACPI_TYPE_PROCESSOR)
           return (ENXIO);
   
       handle = acpi_get_handle(dev);
       if (cpu_softc == NULL)
           cpu_softc = malloc(sizeof(struct acpi_cpu_softc *) *
               (mp_maxid + 1), M_TEMP /* XXX */, M_WAITOK | M_ZERO);
   
       /* Get our Processor object. */
       buf.Pointer = NULL;
       buf.Length = ACPI_ALLOCATE_BUFFER;
       status = AcpiEvaluateObject(handle, NULL, NULL, &buf);
       if (ACPI_FAILURE(status)) {
           device_printf(dev, "probe failed to get Processor obj - %s\n",
                         AcpiFormatException(status));
           return (ENXIO);
       }
       obj = (ACPI_OBJECT *)buf.Pointer;
       if (obj->Type != ACPI_TYPE_PROCESSOR) {
           device_printf(dev, "Processor object has bad type %d\n", obj->Type);
           AcpiOsFree(obj);
           return (ENXIO);
       }
   
       /*
        * Find the processor associated with our unit.  We could use the
        * ProcId as a key, however, some boxes do not have the same values
        * in their Processor object as the ProcId values in the MADT.
        */
       acpi_id = obj->Processor.ProcId;
       AcpiOsFree(obj);
       if (acpi_pcpu_get_id(dev, &acpi_id, &cpu_id) != 0)
           return (ENXIO);
   
       /*
        * Check if we already probed this processor.  We scan the bus twice
        * so it's possible we've already seen this one.
        */
       if (cpu_softc[cpu_id] != NULL)
           return (ENXIO);
   
       /* Mark this processor as in-use and save our derived id for attach. */
       cpu_softc[cpu_id] = (void *)1;
       acpi_set_private(dev, (void*)(intptr_t)cpu_id);
       device_set_desc(dev, "ACPI CPU");
   
       return (0);
   }
   
   static int
   acpi_cpu_attach(device_t dev)
   {
       ACPI_BUFFER            buf;
       ACPI_OBJECT            arg[4], *obj;
       ACPI_OBJECT_LIST       arglist;
       struct pcpu            *pcpu_data;
       struct acpi_cpu_softc *sc;
       struct acpi_softc     *acpi_sc;
       ACPI_STATUS            status;
       u_int                  features;
       int                    cpu_id, drv_count, i;
       driver_t              **drivers;
       uint32_t               cap_set[3];
   
       /* UUID needed by _OSC evaluation */
       static uint8_t cpu_oscuuid[16] = { 0x16, 0xA6, 0x77, 0x40, 0x0C, 0x29,
                                          0xBE, 0x47, 0x9E, 0xBD, 0xD8, 0x70,
                                          0x58, 0x71, 0x39, 0x53 };
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       sc = device_get_softc(dev);
       sc->cpu_dev = dev;
       sc->cpu_handle = acpi_get_handle(dev);
       cpu_id = (int)(intptr_t)acpi_get_private(dev);
       cpu_softc[cpu_id] = sc;
       pcpu_data = pcpu_find(cpu_id);
       pcpu_data->pc_device = dev;
       sc->cpu_pcpu = pcpu_data;
       cpu_smi_cmd = AcpiGbl_FADT.SmiCommand;
       cpu_cst_cnt = AcpiGbl_FADT.CstControl;
   
       buf.Pointer = NULL;
       buf.Length = ACPI_ALLOCATE_BUFFER;
       status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
       if (ACPI_FAILURE(status)) {
           device_printf(dev, "attach failed to get Processor obj - %s\n",
                         AcpiFormatException(status));
           return (ENXIO);
       }
       obj = (ACPI_OBJECT *)buf.Pointer;
       sc->cpu_p_blk = obj->Processor.PblkAddress;
       sc->cpu_p_blk_len = obj->Processor.PblkLength;
       sc->cpu_acpi_id = obj->Processor.ProcId;
       AcpiOsFree(obj);
       ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_BLK at %#x/%d\n",
                        device_get_unit(dev), sc->cpu_p_blk, sc->cpu_p_blk_len));
   
       /*
        * If this is the first cpu we attach, create and initialize the generic
        * resources that will be used by all acpi cpu devices.
        */
       if (device_get_unit(dev) == 0) {
           /* Assume we won't be using generic Cx mode by default */
           cpu_cx_generic = FALSE;
   
           /* Install hw.acpi.cpu sysctl tree */
           acpi_sc = acpi_device_get_parent_softc(dev);
           sysctl_ctx_init(&cpu_sysctl_ctx);
           cpu_sysctl_tree = SYSCTL_ADD_NODE(&cpu_sysctl_ctx,
               SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree), OID_AUTO, "cpu",
               CTLFLAG_RD, 0, "node for CPU children");
   
           /* Queue post cpu-probing task handler */
           AcpiOsExecute(OSL_NOTIFY_HANDLER, acpi_cpu_startup, NULL);
       }
   
       /*
        * Before calling any CPU methods, collect child driver feature hints
        * and notify ACPI of them.  We support unified SMP power control
        * so advertise this ourselves.  Note this is not the same as independent
        * SMP control where each CPU can have different settings.
        */
       sc->cpu_features = ACPI_CAP_SMP_SAME | ACPI_CAP_SMP_SAME_C3;
       if (devclass_get_drivers(acpi_cpu_devclass, &drivers, &drv_count) == 0) {
           for (i = 0; i < drv_count; i++) {
               if (ACPI_GET_FEATURES(drivers[i], &features) == 0)
                   sc->cpu_features |= features;
           }
           free(drivers, M_TEMP);
       }
   
       /*
        * CPU capabilities are specified in
        * Intel Processor Vendor-Specific ACPI Interface Specification.
        */
       if (sc->cpu_features) {
           arglist.Pointer = arg;
           arglist.Count = 4;
           arg[0].Type = ACPI_TYPE_BUFFER;
           arg[0].Buffer.Length = sizeof(cpu_oscuuid);
           arg[0].Buffer.Pointer = cpu_oscuuid;    /* UUID */
           arg[1].Type = ACPI_TYPE_INTEGER;
           arg[1].Integer.Value = 1;               /* revision */
           arg[2].Type = ACPI_TYPE_INTEGER;
           arg[2].Integer.Value = 1;               /* count */
           arg[3].Type = ACPI_TYPE_BUFFER;
           arg[3].Buffer.Length = sizeof(cap_set); /* Capabilities buffer */
           arg[3].Buffer.Pointer = (uint8_t *)cap_set;
           cap_set[0] = 0;                         /* status */
           cap_set[1] = sc->cpu_features;
           status = AcpiEvaluateObject(sc->cpu_handle, "_OSC", &arglist, NULL);
           if (ACPI_SUCCESS(status)) {
               if (cap_set[0] != 0)
                   device_printf(dev, "_OSC returned status %#x\n", cap_set[0]);
           }
           else {
               arglist.Pointer = arg;
               arglist.Count = 1;
               arg[0].Type = ACPI_TYPE_BUFFER;
               arg[0].Buffer.Length = sizeof(cap_set);
               arg[0].Buffer.Pointer = (uint8_t *)cap_set;
               cap_set[0] = 1; /* revision */
               cap_set[1] = 1; /* number of capabilities integers */
               cap_set[2] = sc->cpu_features;
               AcpiEvaluateObject(sc->cpu_handle, "_PDC", &arglist, NULL);
           }
       }
   
       /* Probe for Cx state support. */
       acpi_cpu_cx_probe(sc);
   
       return (0);
   }
   
   static void
   acpi_cpu_postattach(void *unused __unused)
   {
       device_t *devices;
       int err;
       int i, n;
   
       err = devclass_get_devices(acpi_cpu_devclass, &devices, &n);
       if (err != 0) {
           printf("devclass_get_devices(acpi_cpu_devclass) failed\n");
           return;
       }
       for (i = 0; i < n; i++)
           bus_generic_probe(devices[i]);
       for (i = 0; i < n; i++)
           bus_generic_attach(devices[i]);
       free(devices, M_TEMP);
   }
   
   SYSINIT(acpi_cpu, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
       acpi_cpu_postattach, NULL);
   
   static void
   disable_idle(struct acpi_cpu_softc *sc)
   {
       cpuset_t cpuset;
   
       CPU_SETOF(sc->cpu_pcpu->pc_cpuid, &cpuset);
       sc->cpu_disable_idle = TRUE;
   
       /*
        * Ensure that the CPU is not in idle state or in acpi_cpu_idle().
        * Note that this code depends on the fact that the rendezvous IPI
        * can not penetrate context where interrupts are disabled and acpi_cpu_idle
        * is called and executed in such a context with interrupts being re-enabled
        * right before return.
        */
       smp_rendezvous_cpus(cpuset, smp_no_rendevous_barrier, NULL,
           smp_no_rendevous_barrier, NULL);
   }
   
   static void
   enable_idle(struct acpi_cpu_softc *sc)
   {
   
       sc->cpu_disable_idle = FALSE;
   }
   
   static int
   is_idle_disabled(struct acpi_cpu_softc *sc)
   {
   
       return (sc->cpu_disable_idle);
   }
   
   /*
    * Disable any entry to the idle function during suspend and re-enable it
    * during resume.
    */
   static int
   acpi_cpu_suspend(device_t dev)
   {
       int error;
   
       error = bus_generic_suspend(dev);
       if (error)
           return (error);
       disable_idle(device_get_softc(dev));
       return (0);
   }
   
   static int
   acpi_cpu_resume(device_t dev)
   {
   
       enable_idle(device_get_softc(dev));
       return (bus_generic_resume(dev));
   }
   
   /*
    * Find the processor associated with a given ACPI ID.  By default,
    * use the MADT to map ACPI IDs to APIC IDs and use that to locate a
    * processor.  Some systems have inconsistent ASL and MADT however.
    * For these systems the cpu_unordered tunable can be set in which
    * case we assume that Processor objects are listed in the same order
    * in both the MADT and ASL.
    */
   static int
   acpi_pcpu_get_id(device_t dev, uint32_t *acpi_id, uint32_t *cpu_id)
   {
       struct pcpu *pc;
       uint32_t     i, idx;
   
       KASSERT(acpi_id != NULL, ("Null acpi_id"));
       KASSERT(cpu_id != NULL, ("Null cpu_id"));
       idx = device_get_unit(dev);
   
       /*
        * If pc_acpi_id for CPU 0 is not initialized (e.g. a non-APIC
        * UP box) use the ACPI ID from the first processor we find.
        */
       if (idx == 0 && mp_ncpus == 1) {
           pc = pcpu_find(0);
           if (pc->pc_acpi_id == 0xffffffff)
               pc->pc_acpi_id = *acpi_id;
           *cpu_id = 0;
           return (0);
       }
   
       CPU_FOREACH(i) {
           pc = pcpu_find(i);
           KASSERT(pc != NULL, ("no pcpu data for %d", i));
           if (cpu_unordered) {
               if (idx-- == 0) {
                   /*
                    * If pc_acpi_id doesn't match the ACPI ID from the
                    * ASL, prefer the MADT-derived value.
                    */
                   if (pc->pc_acpi_id != *acpi_id)
                       *acpi_id = pc->pc_acpi_id;
                   *cpu_id = pc->pc_cpuid;
                   return (0);
               }
           } else {
               if (pc->pc_acpi_id == *acpi_id) {
                   if (bootverbose)
                       device_printf(dev,
                           "Processor %s (ACPI ID %u) -> APIC ID %d\n",
                           acpi_name(acpi_get_handle(dev)), *acpi_id,
                           pc->pc_cpuid);
                   *cpu_id = pc->pc_cpuid;
                   return (0);
               }
           }
       }
   
       if (bootverbose)
           printf("ACPI: Processor %s (ACPI ID %u) ignored\n",
               acpi_name(acpi_get_handle(dev)), *acpi_id);
   
       return (ESRCH);
   }
   
   static struct resource_list *
   acpi_cpu_get_rlist(device_t dev, device_t child)
   {
       struct acpi_cpu_device *ad;
   
       ad = device_get_ivars(child);
       if (ad == NULL)
           return (NULL);
       return (&ad->ad_rl);
   }
   
   static device_t
   acpi_cpu_add_child(device_t dev, u_int order, const char *name, int unit)
   {
       struct acpi_cpu_device *ad;
       device_t child;
   
       if ((ad = malloc(sizeof(*ad), M_TEMP, M_NOWAIT | M_ZERO)) == NULL)
           return (NULL);
   
       resource_list_init(&ad->ad_rl);
       
       child = device_add_child_ordered(dev, order, name, unit);
       if (child != NULL)
           device_set_ivars(child, ad);
       else
           free(ad, M_TEMP);
       return (child);
   }
   
   static int
   acpi_cpu_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
   {
       struct acpi_cpu_softc *sc;
   
       sc = device_get_softc(dev);
       switch (index) {
       case ACPI_IVAR_HANDLE:
           *result = (uintptr_t)sc->cpu_handle;
           break;
       case CPU_IVAR_PCPU:
           *result = (uintptr_t)sc->cpu_pcpu;
           break;
   #if defined(__amd64__) || defined(__i386__)
       case CPU_IVAR_NOMINAL_MHZ:
           if (tsc_is_invariant) {
               *result = (uintptr_t)(atomic_load_acq_64(&tsc_freq) / 1000000);
               break;
           }
           /* FALLTHROUGH */
   #endif
       default:
           return (ENOENT);
       }
       return (0);
   }
   
   static int
   acpi_cpu_shutdown(device_t dev)
   {
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       /* Allow children to shutdown first. */
       bus_generic_shutdown(dev);
   
       /*
        * Disable any entry to the idle function.
        */
       disable_idle(device_get_softc(dev));
   
       /*
        * CPU devices are not truely detached and remain referenced,
        * so their resources are not freed.
        */
   
       return_VALUE (0);
   }
   
   static void
   acpi_cpu_cx_probe(struct acpi_cpu_softc *sc)
   {
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       /* Use initial sleep value of 1 sec. to start with lowest idle state. */
       sc->cpu_prev_sleep = 1000000;
       sc->cpu_cx_lowest = 0;
       sc->cpu_cx_lowest_lim = 0;
   
       /*
        * Check for the ACPI 2.0 _CST sleep states object. If we can't find
        * any, we'll revert to generic FADT/P_BLK Cx control method which will
        * be handled by acpi_cpu_startup. We need to defer to after having
        * probed all the cpus in the system before probing for generic Cx
        * states as we may already have found cpus with valid _CST packages
        */
       if (!cpu_cx_generic && acpi_cpu_cx_cst(sc) != 0) {
           /*
            * We were unable to find a _CST package for this cpu or there
            * was an error parsing it. Switch back to generic mode.
            */
           cpu_cx_generic = TRUE;
           if (bootverbose)
               device_printf(sc->cpu_dev, "switching to generic Cx mode\n");
       }
   
       /*
        * TODO: _CSD Package should be checked here.
        */
   }
   
   static void
   acpi_cpu_generic_cx_probe(struct acpi_cpu_softc *sc)
   {
       ACPI_GENERIC_ADDRESS         gas;
       struct acpi_cx              *cx_ptr;
   
       sc->cpu_cx_count = 0;
       cx_ptr = sc->cpu_cx_states;
   
       /* Use initial sleep value of 1 sec. to start with lowest idle state. */
       sc->cpu_prev_sleep = 1000000;
   
       /* C1 has been required since just after ACPI 1.0 */
       cx_ptr->type = ACPI_STATE_C1;
       cx_ptr->trans_lat = 0;
       cx_ptr++;
       sc->cpu_non_c2 = sc->cpu_cx_count;
       sc->cpu_non_c3 = sc->cpu_cx_count;
       sc->cpu_cx_count++;
       cpu_deepest_sleep = 1;
   
       /* 
        * The spec says P_BLK must be 6 bytes long.  However, some systems
        * use it to indicate a fractional set of features present so we
        * take 5 as C2.  Some may also have a value of 7 to indicate
        * another C3 but most use _CST for this (as required) and having
        * "only" C1-C3 is not a hardship.
        */
       if (sc->cpu_p_blk_len < 5)
           return; 
   
       /* Validate and allocate resources for C2 (P_LVL2). */
       gas.SpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
       gas.BitWidth = 8;
       if (AcpiGbl_FADT.C2Latency <= 100) {
           gas.Address = sc->cpu_p_blk + 4;
           cx_ptr->res_rid = 0;
           acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &cx_ptr->res_rid,
               &gas, &cx_ptr->p_lvlx, RF_SHAREABLE);
           if (cx_ptr->p_lvlx != NULL) {
               cx_ptr->type = ACPI_STATE_C2;
               cx_ptr->trans_lat = AcpiGbl_FADT.C2Latency;
               cx_ptr++;
               sc->cpu_non_c3 = sc->cpu_cx_count;
               sc->cpu_cx_count++;
               cpu_deepest_sleep = 2;
           }
       }
       if (sc->cpu_p_blk_len < 6)
           return;
   
       /* Validate and allocate resources for C3 (P_LVL3). */
       if (AcpiGbl_FADT.C3Latency <= 1000 && !(cpu_quirks & CPU_QUIRK_NO_C3)) {
           gas.Address = sc->cpu_p_blk + 5;
           cx_ptr->res_rid = 1;
           acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &cx_ptr->res_rid,
               &gas, &cx_ptr->p_lvlx, RF_SHAREABLE);
           if (cx_ptr->p_lvlx != NULL) {
               cx_ptr->type = ACPI_STATE_C3;
               cx_ptr->trans_lat = AcpiGbl_FADT.C3Latency;
               cx_ptr++;
               sc->cpu_cx_count++;
               cpu_deepest_sleep = 3;
           }
       }
   }
   
   /*
    * Parse a _CST package and set up its Cx states.  Since the _CST object
    * can change dynamically, our notify handler may call this function
    * to clean up and probe the new _CST package.
    */
   static int
   acpi_cpu_cx_cst(struct acpi_cpu_softc *sc)
   {
       struct       acpi_cx *cx_ptr;
       ACPI_STATUS  status;
       ACPI_BUFFER  buf;
       ACPI_OBJECT *top;
       ACPI_OBJECT *pkg;
       uint32_t     count;
       int          i;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       buf.Pointer = NULL;
       buf.Length = ACPI_ALLOCATE_BUFFER;
       status = AcpiEvaluateObject(sc->cpu_handle, "_CST", NULL, &buf);
       if (ACPI_FAILURE(status))
           return (ENXIO);
   
       /* _CST is a package with a count and at least one Cx package. */
       top = (ACPI_OBJECT *)buf.Pointer;
       if (!ACPI_PKG_VALID(top, 2) || acpi_PkgInt32(top, 0, &count) != 0) {
           device_printf(sc->cpu_dev, "invalid _CST package\n");
           AcpiOsFree(buf.Pointer);
           return (ENXIO);
       }
       if (count != top->Package.Count - 1) {
           device_printf(sc->cpu_dev, "invalid _CST state count (%d != %d)\n",
                  count, top->Package.Count - 1);
           count = top->Package.Count - 1;
       }
       if (count > MAX_CX_STATES) {
           device_printf(sc->cpu_dev, "_CST has too many states (%d)\n", count);
           count = MAX_CX_STATES;
       }
   
       sc->cpu_non_c2 = 0;
       sc->cpu_non_c3 = 0;
       sc->cpu_cx_count = 0;
       cx_ptr = sc->cpu_cx_states;
   
       /*
        * C1 has been required since just after ACPI 1.0.
        * Reserve the first slot for it.
        */
       cx_ptr->type = ACPI_STATE_C0;
       cx_ptr++;
       sc->cpu_cx_count++;
       cpu_deepest_sleep = 1;
   
       /* Set up all valid states. */
       for (i = 0; i < count; i++) {
           pkg = &top->Package.Elements[i + 1];
           if (!ACPI_PKG_VALID(pkg, 4) ||
               acpi_PkgInt32(pkg, 1, &cx_ptr->type) != 0 ||
               acpi_PkgInt32(pkg, 2, &cx_ptr->trans_lat) != 0 ||
               acpi_PkgInt32(pkg, 3, &cx_ptr->power) != 0) {
   
               device_printf(sc->cpu_dev, "skipping invalid Cx state package\n");
               continue;
           }
   
           /* Validate the state to see if we should use it. */
           switch (cx_ptr->type) {
           case ACPI_STATE_C1:
               if (sc->cpu_cx_states[0].type == ACPI_STATE_C0) {
                   /* This is the first C1 state.  Use the reserved slot. */
                   sc->cpu_cx_states[0] = *cx_ptr;
               } else {
                   sc->cpu_non_c2 = sc->cpu_cx_count;
                   sc->cpu_non_c3 = sc->cpu_cx_count;
                   cx_ptr++;
                   sc->cpu_cx_count++;
               }
               continue;
           case ACPI_STATE_C2:
               sc->cpu_non_c3 = sc->cpu_cx_count;
               if (cpu_deepest_sleep < 2)
                       cpu_deepest_sleep = 2;
               break;
           case ACPI_STATE_C3:
           default:
               if ((cpu_quirks & CPU_QUIRK_NO_C3) != 0) {
                   ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                    "acpi_cpu%d: C3[%d] not available.\n",
                                    device_get_unit(sc->cpu_dev), i));
                   continue;
               } else
                   cpu_deepest_sleep = 3;
               break;
           }
   
           /* Free up any previous register. */
           if (cx_ptr->p_lvlx != NULL) {
               bus_release_resource(sc->cpu_dev, cx_ptr->res_type, cx_ptr->res_rid,
                   cx_ptr->p_lvlx);
               cx_ptr->p_lvlx = NULL;
           }
   
           /* Allocate the control register for C2 or C3. */
           cx_ptr->res_rid = sc->cpu_cx_count;
           acpi_PkgGas(sc->cpu_dev, pkg, 0, &cx_ptr->res_type, &cx_ptr->res_rid,
               &cx_ptr->p_lvlx, RF_SHAREABLE);
           if (cx_ptr->p_lvlx) {
               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                "acpi_cpu%d: Got C%d - %d latency\n",
                                device_get_unit(sc->cpu_dev), cx_ptr->type,
                                cx_ptr->trans_lat));
               cx_ptr++;
               sc->cpu_cx_count++;
           }
       }
       AcpiOsFree(buf.Pointer);
   
       /* If C1 state was not found, we need one now. */
       cx_ptr = sc->cpu_cx_states;
       if (cx_ptr->type == ACPI_STATE_C0) {
           cx_ptr->type = ACPI_STATE_C1;
           cx_ptr->trans_lat = 0;
       }
   
       return (0);
   }
   
   /*
    * Call this *after* all CPUs have been attached.
    */
   static void
   acpi_cpu_startup(void *arg)
   {
       struct acpi_cpu_softc *sc;
       int i;
   
       /* Get set of CPU devices */
       devclass_get_devices(acpi_cpu_devclass, &cpu_devices, &cpu_ndevices);
   
       /*
        * Setup any quirks that might necessary now that we have probed
        * all the CPUs
        */
       acpi_cpu_quirks();
   
       if (cpu_cx_generic) {
           /*
            * We are using generic Cx mode, probe for available Cx states
            * for all processors.
            */
           for (i = 0; i < cpu_ndevices; i++) {
               sc = device_get_softc(cpu_devices[i]);
               acpi_cpu_generic_cx_probe(sc);
           }
       } else {
           /*
            * We are using _CST mode, remove C3 state if necessary.
            * As we now know for sure that we will be using _CST mode
            * install our notify handler.
            */
           for (i = 0; i < cpu_ndevices; i++) {
               sc = device_get_softc(cpu_devices[i]);
               if (cpu_quirks & CPU_QUIRK_NO_C3) {
                   sc->cpu_cx_count = min(sc->cpu_cx_count, sc->cpu_non_c3 + 1);
               }
               AcpiInstallNotifyHandler(sc->cpu_handle, ACPI_DEVICE_NOTIFY,
                   acpi_cpu_notify, sc);
           }
       }
   
       /* Perform Cx final initialization. */
       for (i = 0; i < cpu_ndevices; i++) {
           sc = device_get_softc(cpu_devices[i]);
           acpi_cpu_startup_cx(sc);
       }
   
       /* Add a sysctl handler to handle global Cx lowest setting */
       SYSCTL_ADD_PROC(&cpu_sysctl_ctx, SYSCTL_CHILDREN(cpu_sysctl_tree),
           OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
           NULL, 0, acpi_cpu_global_cx_lowest_sysctl, "A",
           "Global lowest Cx sleep state to use");
   
       /* Take over idling from cpu_idle_default(). */
       cpu_cx_lowest_lim = 0;
       for (i = 0; i < cpu_ndevices; i++) {
           sc = device_get_softc(cpu_devices[i]);
           enable_idle(sc);
       }
       cpu_idle_hook = acpi_cpu_idle;
   }
   
   static void
   acpi_cpu_cx_list(struct acpi_cpu_softc *sc)
   {
       struct sbuf sb;
       int i;
   
       /*
        * Set up the list of Cx states
        */
       sbuf_new(&sb, sc->cpu_cx_supported, sizeof(sc->cpu_cx_supported),
           SBUF_FIXEDLEN);
       for (i = 0; i < sc->cpu_cx_count; i++)
           sbuf_printf(&sb, "C%d/%d/%d ", i + 1, sc->cpu_cx_states[i].type,
               sc->cpu_cx_states[i].trans_lat);
       sbuf_trim(&sb);
       sbuf_finish(&sb);
   }       
   
   static void
   acpi_cpu_startup_cx(struct acpi_cpu_softc *sc)
   {
       acpi_cpu_cx_list(sc);
       
       SYSCTL_ADD_STRING(&sc->cpu_sysctl_ctx,
                         SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
                         OID_AUTO, "cx_supported", CTLFLAG_RD,
                         sc->cpu_cx_supported, 0,
                         "Cx/microsecond values for supported Cx states");
       SYSCTL_ADD_PROC(&sc->cpu_sysctl_ctx,
                       SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
                       OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
                       (void *)sc, 0, acpi_cpu_cx_lowest_sysctl, "A",
                       "lowest Cx sleep state to use");
       SYSCTL_ADD_PROC(&sc->cpu_sysctl_ctx,
                       SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
                       OID_AUTO, "cx_usage", CTLTYPE_STRING | CTLFLAG_RD,
                       (void *)sc, 0, acpi_cpu_usage_sysctl, "A",
                       "percent usage for each Cx state");
   
       /* Signal platform that we can handle _CST notification. */
       if (!cpu_cx_generic && cpu_cst_cnt != 0) {
           ACPI_LOCK(acpi);
           AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
           ACPI_UNLOCK(acpi);
       }
   }
   
   /*
    * Idle the CPU in the lowest state possible.  This function is called with
    * interrupts disabled.  Note that once it re-enables interrupts, a task
    * switch can occur so do not access shared data (i.e. the softc) after
    * interrupts are re-enabled.
    */
   static void
   acpi_cpu_idle(sbintime_t sbt)
   {
       struct      acpi_cpu_softc *sc;
       struct      acpi_cx *cx_next;
       uint64_t    cputicks;
       uint32_t    start_time, end_time;
       int         bm_active, cx_next_idx, i, us;
   
       /*
        * Look up our CPU id to get our softc.  If it's NULL, we'll use C1
        * since there is no ACPI processor object for this CPU.  This occurs
        * for logical CPUs in the HTT case.
        */
       sc = cpu_softc[PCPU_GET(cpuid)];
       if (sc == NULL) {
           acpi_cpu_c1();
           return;
       }
   
       /* If disabled, take the safe path. */
       if (is_idle_disabled(sc)) {
           acpi_cpu_c1();
           return;
       }
   
       /* Find the lowest state that has small enough latency. */
       us = sc->cpu_prev_sleep;
       if (sbt >= 0 && us > (sbt >> 12))
           us = (sbt >> 12);
       cx_next_idx = 0;
       if (cpu_disable_c2_sleep)
           i = min(sc->cpu_cx_lowest, sc->cpu_non_c2);
       else if (cpu_disable_c3_sleep)
          i = min(sc->cpu_cx_lowest, sc->cpu_non_c3);
      else
          i = sc->cpu_cx_lowest;
      for (; i >= 0; i--) {
          if (sc->cpu_cx_states[i].trans_lat * 3 <= us) {
              cx_next_idx = i;
              break;
          }
      }
  
      /*
       * Check for bus master activity.  If there was activity, clear
       * the bit and use the lowest non-C3 state.  Note that the USB
       * driver polling for new devices keeps this bit set all the
       * time if USB is loaded.
       */
      if ((cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0 &&
          cx_next_idx > sc->cpu_non_c3) {
          AcpiReadBitRegister(ACPI_BITREG_BUS_MASTER_STATUS, &bm_active);
          if (bm_active != 0) {
              AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_STATUS, 1);
              cx_next_idx = sc->cpu_non_c3;
          }
      }
  
      /* Select the next state and update statistics. */
      cx_next = &sc->cpu_cx_states[cx_next_idx];
      sc->cpu_cx_stats[cx_next_idx]++;
      KASSERT(cx_next->type != ACPI_STATE_C0, ("acpi_cpu_idle: C0 sleep"));
  
      /*
       * Execute HLT (or equivalent) and wait for an interrupt.  We can't
       * precisely calculate the time spent in C1 since the place we wake up
       * is an ISR.  Assume we slept no more then half of quantum, unless
       * we are called inside critical section, delaying context switch.
       */
      if (cx_next->type == ACPI_STATE_C1) {
          cputicks = cpu_ticks();
          acpi_cpu_c1();
          end_time = ((cpu_ticks() - cputicks) << 20) / cpu_tickrate();
          if (curthread->td_critnest == 0)
                  end_time = min(end_time, 500000 / hz);
          sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 + end_time) / 4;
          return;
      }
  
      /*
       * For C3, disable bus master arbitration and enable bus master wake
       * if BM control is available, otherwise flush the CPU cache.
       */
      if (cx_next->type == ACPI_STATE_C3) {
          if ((cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
              AcpiWriteBitRegister(ACPI_BITREG_ARB_DISABLE, 1);
              AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 1);
          } else
              ACPI_FLUSH_CPU_CACHE();
      }
  
      /*
       * Read from P_LVLx to enter C2(+), checking time spent asleep.
       * Use the ACPI timer for measuring sleep time.  Since we need to
       * get the time very close to the CPU start/stop clock logic, this
       * is the only reliable time source.
       */
      if (cx_next->type == ACPI_STATE_C3) {
          AcpiHwRead(&start_time, &AcpiGbl_FADT.XPmTimerBlock);
          cputicks = 0;
      } else {
          start_time = 0;
          cputicks = cpu_ticks();
      }
      CPU_GET_REG(cx_next->p_lvlx, 1);
  
      /*
       * Read the end time twice.  Since it may take an arbitrary time
       * to enter the idle state, the first read may be executed before
       * the processor has stopped.  Doing it again provides enough
       * margin that we are certain to have a correct value.
       */
      AcpiHwRead(&end_time, &AcpiGbl_FADT.XPmTimerBlock);
      if (cx_next->type == ACPI_STATE_C3) {
          AcpiHwRead(&end_time, &AcpiGbl_FADT.XPmTimerBlock);
          end_time = acpi_TimerDelta(end_time, start_time);
      } else
          end_time = ((cpu_ticks() - cputicks) << 20) / cpu_tickrate();
  
      /* Enable bus master arbitration and disable bus master wakeup. */
      if (cx_next->type == ACPI_STATE_C3 &&
          (cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
          AcpiWriteBitRegister(ACPI_BITREG_ARB_DISABLE, 0);
          AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 0);
      }
      ACPI_ENABLE_IRQS();
  
      sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 + PM_USEC(end_time)) / 4;
  }
  
  /*
   * Re-evaluate the _CST object when we are notified that it changed.
   */
  static void
  acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context)
  {
      struct acpi_cpu_softc *sc = (struct acpi_cpu_softc *)context;
  
      if (notify != ACPI_NOTIFY_CX_STATES)
          return;
  
      /*
       * C-state data for target CPU is going to be in flux while we execute
       * acpi_cpu_cx_cst, so disable entering acpi_cpu_idle.
       * Also, it may happen that multiple ACPI taskqueues may concurrently
       * execute notifications for the same CPU.  ACPI_SERIAL is used to
       * protect against that.
       */
      ACPI_SERIAL_BEGIN(cpu);
      disable_idle(sc);
  
      /* Update the list of Cx states. */
      acpi_cpu_cx_cst(sc);
      acpi_cpu_cx_list(sc);
      acpi_cpu_set_cx_lowest(sc);
  
      enable_idle(sc);
      ACPI_SERIAL_END(cpu);
  
      acpi_UserNotify("PROCESSOR", sc->cpu_handle, notify);
  }
  
  static void
  acpi_cpu_quirks(void)
  {
      ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
  
      /*
       * Bus mastering arbitration control is needed to keep caches coherent
       * while sleeping in C3.  If it's not present but a working flush cache
       * instruction is present, flush the caches before entering C3 instead.
       * Otherwise, just disable C3 completely.
       */
      if (AcpiGbl_FADT.Pm2ControlBlock == 0 ||
          AcpiGbl_FADT.Pm2ControlLength == 0) {
          if ((AcpiGbl_FADT.Flags & ACPI_FADT_WBINVD) &&
              (AcpiGbl_FADT.Flags & ACPI_FADT_WBINVD_FLUSH) == 0) {
              cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
              ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "acpi_cpu: no BM control, using flush cache method\n"));
          } else {
              cpu_quirks |= CPU_QUIRK_NO_C3;
              ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "acpi_cpu: no BM control, C3 not available\n"));
          }
      }
  
      /*
       * If we are using generic Cx mode, C3 on multiple CPUs requires using
       * the expensive flush cache instruction.
       */
      if (cpu_cx_generic && mp_ncpus > 1) {
          cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
          ACPI_DEBUG_PRINT((ACPI_DB_INFO,
              "acpi_cpu: SMP, using flush cache mode for C3\n"));
      }
  
      /* Look for various quirks of the PIIX4 part. */
      acpi_cpu_quirks_piix4();
  }
  
  static void
  acpi_cpu_quirks_piix4(void)
  {
  #ifdef __i386__
      device_t acpi_dev;
      uint32_t val;
  
      acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
      if (acpi_dev != NULL) {
          switch (pci_get_revid(acpi_dev)) {
          /*
           * Disable C3 support for all PIIX4 chipsets.  Some of these parts
           * do not report the BMIDE status to the BM status register and
           * others have a livelock bug if Type-F DMA is enabled.  Linux
           * works around the BMIDE bug by reading the BM status directly
           * but we take the simpler approach of disabling C3 for these
           * parts.
           *
           * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
           * Livelock") from the January 2002 PIIX4 specification update.
           * Applies to all PIIX4 models.
           *
           * Also, make sure that all interrupts cause a "Stop Break"
           * event to exit from C2 state.
           * Also, BRLD_EN_BM (ACPI_BITREG_BUS_MASTER_RLD in ACPI-speak)
           * should be set to zero, otherwise it causes C2 to short-sleep.
           * PIIX4 doesn't properly support C3 and bus master activity
           * need not break out of C2.
           */
          case PCI_REVISION_A_STEP:
          case PCI_REVISION_B_STEP:
          case PCI_REVISION_4E:
          case PCI_REVISION_4M:
              cpu_quirks |= CPU_QUIRK_NO_C3;
              ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "acpi_cpu: working around PIIX4 bug, disabling C3\n"));
  
              val = pci_read_config(acpi_dev, PIIX4_DEVACTB_REG, 4);
              if ((val & PIIX4_STOP_BREAK_MASK) != PIIX4_STOP_BREAK_MASK) {
                  ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                      "acpi_cpu: PIIX4: enabling IRQs to generate Stop Break\n"));
                  val |= PIIX4_STOP_BREAK_MASK;
                  pci_write_config(acpi_dev, PIIX4_DEVACTB_REG, val, 4);
              }
              AcpiReadBitRegister(ACPI_BITREG_BUS_MASTER_RLD, &val);
              if (val) {
                  ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                      "acpi_cpu: PIIX4: reset BRLD_EN_BM\n"));
                  AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 0);
              }
              break;
          default:
              break;
          }
      }
  #endif
  }
  
  static int
  acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS)
  {
      struct acpi_cpu_softc *sc;
      struct sbuf  sb;
      char         buf[128];
      int          i;
      uintmax_t    fract, sum, whole;
  
      sc = (struct acpi_cpu_softc *) arg1;
      sum = 0;
      for (i = 0; i < sc->cpu_cx_count; i++)
          sum += sc->cpu_cx_stats[i];
      sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
      for (i = 0; i < sc->cpu_cx_count; i++) {
          if (sum > 0) {
              whole = (uintmax_t)sc->cpu_cx_stats[i] * 100;
              fract = (whole % sum) * 100;
              sbuf_printf(&sb, "%u.%02u%% ", (u_int)(whole / sum),
                  (u_int)(fract / sum));
          } else
              sbuf_printf(&sb, "0.00%% ");
      }
      sbuf_printf(&sb, "last %dus", sc->cpu_prev_sleep);
      sbuf_trim(&sb);
      sbuf_finish(&sb);
      sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
      sbuf_delete(&sb);
  
      return (0);
  }
  
  static int
  acpi_cpu_set_cx_lowest(struct acpi_cpu_softc *sc)
  {
      int i;
  
      ACPI_SERIAL_ASSERT(cpu);
      sc->cpu_cx_lowest = min(sc->cpu_cx_lowest_lim, sc->cpu_cx_count - 1);
  
      /* If not disabling, cache the new lowest non-C3 state. */
      sc->cpu_non_c3 = 0;
      for (i = sc->cpu_cx_lowest; i >= 0; i--) {
          if (sc->cpu_cx_states[i].type < ACPI_STATE_C3) {
              sc->cpu_non_c3 = i;
              break;
          }
      }
  
      /* Reset the statistics counters. */
      bzero(sc->cpu_cx_stats, sizeof(sc->cpu_cx_stats));
      return (0);
  }
  
  static int
  acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
  {
      struct       acpi_cpu_softc *sc;
      char         state[8];
      int          val, error;
  
      sc = (struct acpi_cpu_softc *) arg1;
      snprintf(state, sizeof(state), "C%d", sc->cpu_cx_lowest_lim + 1);
      error = sysctl_handle_string(oidp, state, sizeof(state), req);
      if (error != 0 || req->newptr == NULL)
          return (error);
      if (strlen(state) < 2 || toupper(state[0]) != 'C')
          return (EINVAL);
      if (strcasecmp(state, "Cmax") == 0)
          val = MAX_CX_STATES;
      else {
          val = (int) strtol(state + 1, NULL, 10);
          if (val < 1 || val > MAX_CX_STATES)
              return (EINVAL);
      }
  
      ACPI_SERIAL_BEGIN(cpu);
      sc->cpu_cx_lowest_lim = val - 1;
      acpi_cpu_set_cx_lowest(sc);
      ACPI_SERIAL_END(cpu);
  
      return (0);
  }
  
  static int
  acpi_cpu_global_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
  {
      struct      acpi_cpu_softc *sc;
      char        state[8];
      int         val, error, i;
  
      snprintf(state, sizeof(state), "C%d", cpu_cx_lowest_lim + 1);
      error = sysctl_handle_string(oidp, state, sizeof(state), req);
      if (error != 0 || req->newptr == NULL)
          return (error);
      if (strlen(state) < 2 || toupper(state[0]) != 'C')
          return (EINVAL);
      if (strcasecmp(state, "Cmax") == 0)
          val = MAX_CX_STATES;
      else {
          val = (int) strtol(state + 1, NULL, 10);
          if (val < 1 || val > MAX_CX_STATES)
              return (EINVAL);
      }
  
      /* Update the new lowest useable Cx state for all CPUs. */
      ACPI_SERIAL_BEGIN(cpu);
      cpu_cx_lowest_lim = val - 1;
      for (i = 0; i < cpu_ndevices; i++) {
          sc = device_get_softc(cpu_devices[i]);
          sc->cpu_cx_lowest_lim = cpu_cx_lowest_lim;
          acpi_cpu_set_cx_lowest(sc);
      }
      ACPI_SERIAL_END(cpu);
  
      return (0);
  }

Cache object: a3bf009163b1fdf6b87603f9fd6f19da