This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / include / xen / interface / io / blkif.h

diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
new file mode 100644 (file)
index 0000000..e29e400
--- /dev/null
+++ b/include/xen/interface/io/blkif.h
@@ -0,0 +1,87 @@
+/******************************************************************************
+ * blkif.h
+ * 
+ * Unified block-device I/O interface for Xen guest OSes.
+ * 
+ * Copyright (c) 2003-2004, Keir Fraser
+ */
+
+#ifndef __XEN_PUBLIC_IO_BLKIF_H__
+#define __XEN_PUBLIC_IO_BLKIF_H__
+
+#include "ring.h"
+#include "../grant_table.h"
+
+/*
+ * Front->back notifications: When enqueuing a new request, sending a
+ * notification can be made conditional on req_event (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Backends must set
+ * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
+ * 
+ * Back->front notifications: When enqueuing a new response, sending a
+ * notification can be made conditional on rsp_event (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Frontends must set
+ * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
+ */
+
+#ifndef blkif_vdev_t
+#define blkif_vdev_t   uint16_t
+#endif
+#define blkif_sector_t uint64_t
+
+#define BLKIF_OP_READ      0
+#define BLKIF_OP_WRITE     1
+
+/*
+ * Maximum scatter/gather segments per request.
+ * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE.
+ * NB. This could be 12 if the ring indexes weren't stored in the same page.
+ */
+#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
+
+struct blkif_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 {
+        grant_ref_t gref;        /* reference to I/O buffer frame        */
+        /* @first_sect: first sector in frame to transfer (inclusive).   */
+        /* @last_sect: last sector in frame to transfer (inclusive).     */
+        uint8_t     first_sect, last_sect;
+    } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+};
+typedef struct blkif_request blkif_request_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;
+
+#define BLKIF_RSP_ERROR  -1 /* non-specific 'error' */
+#define BLKIF_RSP_OKAY    0 /* non-specific 'okay'  */
+
+/*
+ * Generate blkif ring structures and types.
+ */
+
+DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
+
+#define VDISK_CDROM        0x1
+#define VDISK_REMOVABLE    0x2
+#define VDISK_READONLY     0x4
+
+#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-set-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */