Thu Apr 16 15:58:13 2020 UTC ()

update padding within 'struct blkif_request_indirect' to be binary
compatible with Linux/i386 - they changed padding so that there is no
structure layout difference between i386 and amd64; there is no change
for amd64 due to implicit padding

since Linux seems to be the only xen blkback implementation supporting
indirect segments, follow that rather than public xen includes; note
their blkif_x86_32_request_indirect handling expect this layout,
particularly padding for i386 before indirect_grefs[]


(jdolecek)

diff -r1.1.1.1 -r1.2 src/sys/external/mit/xen-include-public/dist/xen/include/public/io/blkif.h

--- src/sys/external/mit/xen-include-public/dist/xen/include/public/io/blkif.h 2019/02/02 08:03:48	1.1.1.1
+++ src/sys/external/mit/xen-include-public/dist/xen/include/public/io/blkif.h 2020/04/16 15:58:13	1.2

 @@ -643,34 +643,40 @@ struct blkif_request_discard {
     uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
 #define BLKIF_DISCARD_SECURE (1<<0)  /* ignored if discard-secure=0      */
     blkif_vdev_t   handle;       /* same as for read/write requests      */
     uint64_t       id;           /* private guest value, echoed in resp  */
     blkif_sector_t sector_number;/* start sector idx on disk             */
     uint64_t       nr_sectors;   /* number of contiguous sectors to discard*/
 };
 typedef struct blkif_request_discard blkif_request_discard_t;
 struct blkif_request_indirect {
     uint8_t        operation;    /* BLKIF_OP_INDIRECT                    */
     uint8_t        indirect_op;  /* BLKIF_OP_{READ/WRITE}                */
     uint16_t       nr_segments;  /* number of segments                   */
 #ifndef __i386__
     uint32_t	   _pad1;
 #endif
     uint64_t       id;           /* private guest value, echoed in resp  */
     blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
     blkif_vdev_t   handle;       /* same as for read/write requests      */
     uint16_t       _pad2;
     grant_ref_t    indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
-#ifdef __i386__
+#ifndef __i386__
-    uint64_t       pad;          /* Make it 64 byte aligned on i386      */
+    uint32_t       _pad3;        /* Make it 64 byte aligned */
 #else
     uint64_t       _pad3;        /* Make it 64 byte aligned */
 #endif
-};
+} __packed;
 typedef struct blkif_request_indirect blkif_request_indirect_t;
 struct blkif_response {
     uint64_t        id;              /* copied from request */
     uint8_t         operation;       /* copied from request */
     int16_t         status;          /* BLKIF_RSP_???       */
 };
 typedef struct blkif_response blkif_response_t;
 /*
  * STATUS RETURN CODES.
  */
  /* Operation not supported (only happens on barrier writes). */