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

/******************************************************************************
 * 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()).
 */

typedef uint16_t blkif_vdev_t;
typedef uint64_t blkif_sector_t;

/*
 * REQUEST CODES.
 */
#define BLKIF_OP_READ              0
#define BLKIF_OP_WRITE             1
/*
 * Recognised only if "feature-barrier" is present in backend xenbus info.
 * The "feature_barrier" node contains a boolean indicating whether barrier
 * requests are likely to succeed or fail. Either way, a barrier request
 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
 * the underlying block-device hardware. The boolean simply indicates whether
 * or not it is worthwhile for the frontend to attempt barrier requests.
 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
 * create the "feature-barrier" node!
 */
#define BLKIF_OP_WRITE_BARRIER     2

/*
 * Maximum scatter/gather segments per request.
 * This is carefully chosen so that sizeof(struct blkif_ring) <= 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_rw {
	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];
};

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  */
	union {
		struct blkif_request_rw rw;
	} u;
};

struct blkif_response {
	uint64_t        id;              /* copied from request */
	uint8_t         operation;       /* copied from request */
	int16_t         status;          /* BLKIF_RSP_???       */
};

/*
 * STATUS RETURN CODES.
 */
 /* Operation not supported (only happens on barrier writes). */
#define BLKIF_RSP_EOPNOTSUPP  -2
 /* Operation failed for some unspecified reason (-EIO). */
#define BLKIF_RSP_ERROR       -1
 /* Operation completed successfully. */
#define BLKIF_RSP_OKAY         0

/*
 * 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

/* Xen-defined major numbers for virtual disks, they look strangely
 * familiar */
#define XEN_IDE0_MAJOR	3
#define XEN_IDE1_MAJOR	22
#define XEN_SCSI_DISK0_MAJOR	8
#define XEN_SCSI_DISK1_MAJOR	65
#define XEN_SCSI_DISK2_MAJOR	66
#define XEN_SCSI_DISK3_MAJOR	67
#define XEN_SCSI_DISK4_MAJOR	68
#define XEN_SCSI_DISK5_MAJOR	69
#define XEN_SCSI_DISK6_MAJOR	70
#define XEN_SCSI_DISK7_MAJOR	71
#define XEN_SCSI_DISK8_MAJOR	128
#define XEN_SCSI_DISK9_MAJOR	129
#define XEN_SCSI_DISK10_MAJOR	130
#define XEN_SCSI_DISK11_MAJOR	131
#define XEN_SCSI_DISK12_MAJOR	132
#define XEN_SCSI_DISK13_MAJOR	133
#define XEN_SCSI_DISK14_MAJOR	134
#define XEN_SCSI_DISK15_MAJOR	135

#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
Commit	Line	Data
a42089dd JF	1	/******************************************************************************
	2	* blkif.h
	3	*
	4	* Unified block-device I/O interface for Xen guest OSes.
	5	*
	6	* Copyright (c) 2003-2004, Keir Fraser
	7	*/
	8
	9	#ifndef __XEN_PUBLIC_IO_BLKIF_H__
	10	#define __XEN_PUBLIC_IO_BLKIF_H__
	11
	12	#include "ring.h"
	13	#include "../grant_table.h"
	14
	15	/*
	16	* Front->back notifications: When enqueuing a new request, sending a
	17	* notification can be made conditional on req_event (i.e., the generic
	18	* hold-off mechanism provided by the ring macros). Backends must set
	19	* req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
	20	*
	21	* Back->front notifications: When enqueuing a new response, sending a
	22	* notification can be made conditional on rsp_event (i.e., the generic
	23	* hold-off mechanism provided by the ring macros). Frontends must set
	24	* rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
	25	*/
	26
	27	typedef uint16_t blkif_vdev_t;
	28	typedef uint64_t blkif_sector_t;
	29
	30	/*
	31	* REQUEST CODES.
	32	*/
	33	#define BLKIF_OP_READ 0
	34	#define BLKIF_OP_WRITE 1
	35	/*
	36	* Recognised only if "feature-barrier" is present in backend xenbus info.
	37	* The "feature_barrier" node contains a boolean indicating whether barrier
	38	* requests are likely to succeed or fail. Either way, a barrier request
	39	* may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
	40	* the underlying block-device hardware. The boolean simply indicates whether
	41	* or not it is worthwhile for the frontend to attempt barrier requests.
	42	* If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should not
	43	* create the "feature-barrier" node!
	44	*/
	45	#define BLKIF_OP_WRITE_BARRIER 2
	46
	47	/*
	48	* Maximum scatter/gather segments per request.
	49	* This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
	50	* NB. This could be 12 if the ring indexes weren't stored in the same page.
	51	*/
	52	#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
	53
51de6952	54	struct blkif_request_rw {
a42089dd JF	55	blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
	56	struct blkif_request_segment {
	57	grant_ref_t gref; /* reference to I/O buffer frame */
	58	/* @first_sect: first sector in frame to transfer (inclusive). */
	59	/* @last_sect: last sector in frame to transfer (inclusive). */
	60	uint8_t first_sect, last_sect;
	61	} seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
	62	};
	63
51de6952 OS	64	struct blkif_request {
	65	uint8_t operation; /* BLKIF_OP_??? */
	66	uint8_t nr_segments; /* number of segments */
	67	blkif_vdev_t handle; /* only for read/write requests */
	68	uint64_t id; /* private guest value, echoed in resp */
	69	union {
	70	struct blkif_request_rw rw;
	71	} u;
	72	};
	73
a42089dd JF	74	struct blkif_response {
	75	uint64_t id; /* copied from request */
	76	uint8_t operation; /* copied from request */
	77	int16_t status; /* BLKIF_RSP_??? */
	78	};
	79
	80	/*
	81	* STATUS RETURN CODES.
	82	*/
	83	/* Operation not supported (only happens on barrier writes). */
	84	#define BLKIF_RSP_EOPNOTSUPP -2
	85	/* Operation failed for some unspecified reason (-EIO). */
	86	#define BLKIF_RSP_ERROR -1
	87	/* Operation completed successfully. */
	88	#define BLKIF_RSP_OKAY 0
	89
	90	/*
	91	* Generate blkif ring structures and types.
	92	*/
	93
	94	DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
	95
	96	#define VDISK_CDROM 0x1
	97	#define VDISK_REMOVABLE 0x2
	98	#define VDISK_READONLY 0x4
	99
c80a4209 SS	100	/* Xen-defined major numbers for virtual disks, they look strangely
	101	* familiar */
	102	#define XEN_IDE0_MAJOR 3
	103	#define XEN_IDE1_MAJOR 22
	104	#define XEN_SCSI_DISK0_MAJOR 8
	105	#define XEN_SCSI_DISK1_MAJOR 65
	106	#define XEN_SCSI_DISK2_MAJOR 66
	107	#define XEN_SCSI_DISK3_MAJOR 67
	108	#define XEN_SCSI_DISK4_MAJOR 68
	109	#define XEN_SCSI_DISK5_MAJOR 69
	110	#define XEN_SCSI_DISK6_MAJOR 70
	111	#define XEN_SCSI_DISK7_MAJOR 71
	112	#define XEN_SCSI_DISK8_MAJOR 128
	113	#define XEN_SCSI_DISK9_MAJOR 129
	114	#define XEN_SCSI_DISK10_MAJOR 130
	115	#define XEN_SCSI_DISK11_MAJOR 131
	116	#define XEN_SCSI_DISK12_MAJOR 132
	117	#define XEN_SCSI_DISK13_MAJOR 133
	118	#define XEN_SCSI_DISK14_MAJOR 134
	119	#define XEN_SCSI_DISK15_MAJOR 135
	120
a42089dd	121	#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */