FreeBSD/Linux Kernel Cross Reference
sys/dev/virtio/block/virtio_blk.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * This header is BSD licensed so anyone can use the definitions to implement
      * compatible drivers/servers.
      *
      * 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.
     * 3. Neither the name of IBM nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 IBM 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.
     *
     * $FreeBSD$
     */
    
    #ifndef _VIRTIO_BLK_H
    #define _VIRTIO_BLK_H
    
    /* Feature bits */
    #define VIRTIO_BLK_F_SIZE_MAX           0x0002  /* Indicates maximum segment size */
    #define VIRTIO_BLK_F_SEG_MAX            0x0004  /* Indicates maximum # of segments */
    #define VIRTIO_BLK_F_GEOMETRY           0x0010  /* Legacy geometry available  */
    #define VIRTIO_BLK_F_RO                 0x0020  /* Disk is read-only */
    #define VIRTIO_BLK_F_BLK_SIZE           0x0040  /* Block size of disk is available*/
    #define VIRTIO_BLK_F_FLUSH              0x0200  /* Flush command supported */
    #define VIRTIO_BLK_F_TOPOLOGY           0x0400  /* Topology information is available */
    #define VIRTIO_BLK_F_CONFIG_WCE         0x0800  /* Writeback mode available in config */
    #define VIRTIO_BLK_F_MQ                 0x1000  /* Support more than one vq */
    #define VIRTIO_BLK_F_DISCARD            0x2000  /* DISCARD is supported */
    #define VIRTIO_BLK_F_WRITE_ZEROES       0x4000  /* WRITE ZEROES is supported */
    
    /* Legacy feature bits */
    #define VIRTIO_BLK_F_BARRIER    0x0001  /* Does host support barriers? */
    #define VIRTIO_BLK_F_SCSI       0x0080  /* Supports scsi command passthru */
    
    /* Old (deprecated) name for VIRTIO_BLK_F_FLUSH. */
    #define VIRTIO_BLK_F_WCE VIRTIO_BLK_F_FLUSH
    
    #define VIRTIO_BLK_ID_BYTES     20      /* ID string length */
    
    struct virtio_blk_config {
            /* The capacity (in 512-byte sectors). */
            uint64_t capacity;
            /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
            uint32_t size_max;
            /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
            uint32_t seg_max;
            /* Geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
            struct virtio_blk_geometry {
                    uint16_t cylinders;
                    uint8_t heads;
                    uint8_t sectors;
            } geometry;
    
            /* Block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
            uint32_t blk_size;
    
            /* Topology of the device (if VIRTIO_BLK_F_TOPOLOGY) */
            struct virtio_blk_topology {
                    /* Exponent for physical block per logical block. */
                    uint8_t physical_block_exp;
                    /* Alignment offset in logical blocks. */
                    uint8_t alignment_offset;
                    /* Minimum I/O size without performance penalty in logical
                     * blocks. */
                    uint16_t min_io_size;
                    /* Optimal sustained I/O size in logical blocks. */
                    uint32_t opt_io_size;
            } topology;
    
            /* Writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
            uint8_t wce;
            uint8_t unused;
    
            /* Number of vqs, only available when VIRTIO_BLK_F_MQ is set */
            uint16_t num_queues;
    
            /*
             * The next 3 entries are guarded by VIRTIO_BLK_F_DISCARD.
             *
             * The maximum discard sectors (in 512-byte sectors) for
             * one segment.
            */
           uint32_t max_discard_sectors;
           /*
            * The maximum number of discard segments in a
            * discard command.
            */
           uint32_t max_discard_seg;
           /* Discard commands must be aligned to this number of sectors. */
           uint32_t discard_sector_alignment;
   
           /*
            * The next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES
            *
            * The maximum number of write zeroes sectors (in 512-byte sectors) in
            * one segment.
            */
           uint32_t max_write_zeroes_sectors;
           /*
            * The maximum number of segments in a write zeroes
            * command.
            */
           uint32_t max_write_zeroes_seg;
           /*
            * Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
            * deallocation of one or more of the sectors.
            */
           uint8_t write_zeroes_may_unmap;
   
           uint8_t unused1[3];
   } __packed;
   
   /*
    * Command types
    *
    * Usage is a bit tricky as some bits are used as flags and some are not.
    *
    * Rules:
    *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
    *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
    *   and may not be combined with any of the other flags.
    */
   
   /* These two define direction. */
   #define VIRTIO_BLK_T_IN                 0
   #define VIRTIO_BLK_T_OUT                1
   
   /* This bit says it's a scsi command, not an actual read or write. */
   #define VIRTIO_BLK_T_SCSI_CMD           2
   #define VIRTIO_BLK_T_SCSI_CMD_OUT       3
   
   /* Cache flush command */
   #define VIRTIO_BLK_T_FLUSH              4
   #define VIRTIO_BLK_T_FLUSH_OUT          5
   
   /* Get device ID command */
   #define VIRTIO_BLK_T_GET_ID             8
   
   /* Discard command */
   #define VIRTIO_BLK_T_DISCARD            11
   
   /* Write zeros command */
   #define VIRTIO_BLK_T_WRITE_ZEROES       13
   
   /* Barrier before this op. */
   #define VIRTIO_BLK_T_BARRIER            0x80000000
   
   /* Unmap this range (only valid for write zeroes command) */
   #define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP      0x00000001
   
   /*
    * This comes first in the read scatter-gather list.
    * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
    * this is the first element of the read scatter-gather list.
    */
   struct virtio_blk_outhdr {
           /* VIRTIO_BLK_T* */
           uint32_t type;
           /* io priority. */
           uint32_t ioprio;
           /* Sector (ie. 512 byte offset) */
           uint64_t sector;
   };
   
   /* Unmap this range (only valid for write zeroes command) */
   #define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP      0x00000001
   
   /* Discard/write zeroes range for each request. */
   struct virtio_blk_discard_write_zeroes {
           /* Discard/write zeroes start sector */
           uint64_t sector;
           /* Number of discard/write zeroes sectors */
           uint32_t num_sectors;
           /* Flags for this range */
           uint32_t flags;
   };
   
   struct virtio_scsi_inhdr {
           uint32_t errors;
           uint32_t data_len;
           uint32_t sense_len;
           uint32_t residual;
   };
   
   /* And this is the final byte of the write scatter-gather list. */
   #define VIRTIO_BLK_S_OK         0
   #define VIRTIO_BLK_S_IOERR      1
   #define VIRTIO_BLK_S_UNSUPP     2
   
   #endif /* _VIRTIO_BLK_H */

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