FreeBSD/Linux Kernel Cross Reference
sys/xen/blkif.h

     /* 
      * Permission is hereby granted, free of charge, to any person obtaining a copy
      * of this software and associated documentation files (the "Software"), to
      * deal in the Software without restriction, including without limitation the
      * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
      * sell copies of the Software, and to permit persons to whom the Software is
      * furnished to do so, subject to the following conditions:
      *
      * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     * DEALINGS IN THE SOFTWARE.
     *
     * $FreeBSD$
     */
    
    #ifndef __XEN_BLKIF_H__
    #define __XEN_BLKIF_H__
    
    #include <contrib/xen/io/ring.h>
    #include <contrib/xen/io/blkif.h>
    #include <contrib/xen/io/protocols.h>
    
    /* Not a real protocol.  Used to generate ring structs which contain
     * the elements common to all protocols only.  This way we get a
     * compiler-checkable way to use common struct elements, so we can
     * avoid using switch(protocol) in a number of places.  */
    struct blkif_common_request {
            char dummy;
    };
    struct blkif_common_response {
            char dummy;
    };
    
    /* i386 protocol version */
    #pragma pack(push, 4)
    struct blkif_x86_32_request {
            uint8_t        operation;    /* BLKIF_OP_???                         */
            uint8_t        nr_segments;  /* number of segments                   */
            blkif_vdev_t   handle;       /* only for read/write requests         */
            uint64_t       id;           /* private guest value, echoed in resp  */
            blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
            struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
    };
    struct blkif_x86_32_response {
            uint64_t        id;              /* copied from request */
            uint8_t         operation;       /* copied from request */
            int16_t         status;          /* BLKIF_RSP_???       */
    };
    typedef struct blkif_x86_32_request blkif_x86_32_request_t;
    typedef struct blkif_x86_32_response blkif_x86_32_response_t;
    #pragma pack(pop)
    
    /* x86_64 protocol version */
    struct blkif_x86_64_request {
            uint8_t        operation;    /* BLKIF_OP_???                         */
            uint8_t        nr_segments;  /* number of segments                   */
            blkif_vdev_t   handle;       /* only for read/write requests         */
            uint64_t       __attribute__((__aligned__(8))) id;
            blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
            struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
    };
    struct blkif_x86_64_response {
            uint64_t       __attribute__((__aligned__(8))) id;
            uint8_t         operation;       /* copied from request */
            int16_t         status;          /* BLKIF_RSP_???       */
    };
    typedef struct blkif_x86_64_request blkif_x86_64_request_t;
    typedef struct blkif_x86_64_response blkif_x86_64_response_t;
    
    DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, struct blkif_common_response);
    DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct blkif_x86_32_response);
    DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct blkif_x86_64_response);
    
    /*
     * Maximum number of requests that can be active for a given instance
     * regardless of the protocol in use, based on the ring size.  This constant
     * facilitates resource pre-allocation in backend drivers since the size is
     * known well in advance of attaching to a front end.
     */
    #define BLKIF_MAX_RING_REQUESTS(_sz) \
            MAX(__RING_SIZE((blkif_x86_64_sring_t *)NULL, _sz),     \
                MAX(__RING_SIZE((blkif_x86_32_sring_t *)NULL, _sz), \
                    __RING_SIZE((blkif_sring_t *)NULL, _sz)))
    
    /*
     * The number of ring pages required to support a given number of requests
     * for a given instance regardless of the protocol in use.
     */
    #define BLKIF_RING_PAGES(_entries) \
            MAX(__RING_PAGES((blkif_x86_64_sring_t *)NULL, _entries),       \
                MAX(__RING_PAGES((blkif_x86_32_sring_t *)NULL, _entries),   \
                    __RING_PAGES((blkif_sring_t *)NULL, _entries)))
   
   union blkif_back_rings {
           blkif_back_ring_t        native;
           blkif_common_back_ring_t common;
           blkif_x86_32_back_ring_t x86_32;
           blkif_x86_64_back_ring_t x86_64;
   };
   typedef union blkif_back_rings blkif_back_rings_t;
   
   enum blkif_protocol {
           BLKIF_PROTOCOL_NATIVE = 1,
           BLKIF_PROTOCOL_X86_32 = 2,
           BLKIF_PROTOCOL_X86_64 = 3,
   };
   
   static void inline blkif_get_x86_32_req(blkif_request_t *dst, blkif_x86_32_request_t *src)
   {
           int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
           dst->operation = src->operation;
           dst->nr_segments = src->nr_segments;
           dst->handle = src->handle;
           dst->id = src->id;
           dst->sector_number = src->sector_number;
           __compiler_membar();
           if (n > dst->nr_segments)
                   n = dst->nr_segments;
           for (i = 0; i < n; i++)
                   dst->seg[i] = src->seg[i];
   }
   
   static void inline blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_request_t *src)
   {
           int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
           dst->operation = src->operation;
           dst->nr_segments = src->nr_segments;
           dst->handle = src->handle;
           dst->id = src->id;
           dst->sector_number = src->sector_number;
           __compiler_membar();
           if (n > dst->nr_segments)
                   n = dst->nr_segments;
           for (i = 0; i < n; i++)
                   dst->seg[i] = src->seg[i];
   }
   
   #endif /* __XEN_BLKIF_H__ */

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