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212 lines
7.7 KiB
212 lines
7.7 KiB
/* SPDX-License-Identifier: MIT */ |
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/****************************************************************************** |
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* vscsiif.h |
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* |
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* Based on the blkif.h code. |
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* |
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* Copyright(c) FUJITSU Limited 2008. |
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*/ |
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#ifndef __XEN__PUBLIC_IO_SCSI_H__ |
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#define __XEN__PUBLIC_IO_SCSI_H__ |
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#include "ring.h" |
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#include "../grant_table.h" |
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/* |
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* Feature and Parameter Negotiation |
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* ================================= |
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* The two halves of a Xen pvSCSI driver utilize nodes within the XenStore to |
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* communicate capabilities and to negotiate operating parameters. This |
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* section enumerates these nodes which reside in the respective front and |
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* backend portions of the XenStore, following the XenBus convention. |
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* |
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* Any specified default value is in effect if the corresponding XenBus node |
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* is not present in the XenStore. |
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* |
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* XenStore nodes in sections marked "PRIVATE" are solely for use by the |
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* driver side whose XenBus tree contains them. |
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* |
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***************************************************************************** |
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* Backend XenBus Nodes |
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***************************************************************************** |
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* |
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*------------------ Backend Device Identification (PRIVATE) ------------------ |
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* |
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* p-devname |
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* Values: string |
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* |
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* A free string used to identify the physical device (e.g. a disk name). |
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* |
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* p-dev |
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* Values: string |
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* |
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* A string specifying the backend device: either a 4-tuple "h:c:t:l" |
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* (host, controller, target, lun, all integers), or a WWN (e.g. |
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* "naa.60014054ac780582"). |
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* |
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* v-dev |
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* Values: string |
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* |
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* A string specifying the frontend device in form of a 4-tuple "h:c:t:l" |
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* (host, controller, target, lun, all integers). |
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* |
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*--------------------------------- Features --------------------------------- |
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* |
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* feature-sg-grant |
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* Values: unsigned [VSCSIIF_SG_TABLESIZE...65535] |
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* Default Value: 0 |
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* |
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* Specifies the maximum number of scatter/gather elements in grant pages |
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* supported. If not set, the backend supports up to VSCSIIF_SG_TABLESIZE |
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* SG elements specified directly in the request. |
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* |
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***************************************************************************** |
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* Frontend XenBus Nodes |
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***************************************************************************** |
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* |
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*----------------------- Request Transport Parameters ----------------------- |
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* |
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* event-channel |
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* Values: unsigned |
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* |
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* The identifier of the Xen event channel used to signal activity |
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* in the ring buffer. |
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* |
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* ring-ref |
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* Values: unsigned |
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* |
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* The Xen grant reference granting permission for the backend to map |
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* the sole page in a single page sized ring buffer. |
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* |
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* protocol |
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* Values: string (XEN_IO_PROTO_ABI_*) |
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* Default Value: XEN_IO_PROTO_ABI_NATIVE |
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* |
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* The machine ABI rules governing the format of all ring request and |
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* response structures. |
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*/ |
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/* Requests from the frontend to the backend */ |
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/* |
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* Request a SCSI operation specified via a CDB in vscsiif_request.cmnd. |
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* The target is specified via channel, id and lun. |
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* |
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* The operation to be performed is specified via a CDB in cmnd[], the length |
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* of the CDB is in cmd_len. sc_data_direction specifies the direction of data |
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* (to the device, from the device, or none at all). |
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* |
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* If data is to be transferred to or from the device the buffer(s) in the |
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* guest memory is/are specified via one or multiple scsiif_request_segment |
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* descriptors each specifying a memory page via a grant_ref_t, a offset into |
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* the page and the length of the area in that page. All scsiif_request_segment |
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* areas concatenated form the resulting data buffer used by the operation. |
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* If the number of scsiif_request_segment areas is not too large (less than |
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* or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the |
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* seg[] array and the number of valid scsiif_request_segment elements is to be |
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* set in nr_segments. |
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* |
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* If "feature-sg-grant" in the Xenstore is set it is possible to specify more |
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* than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection. |
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* The maximum number of allowed scsiif_request_segment elements is the value |
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* of the "feature-sg-grant" entry from Xenstore. When using indirection the |
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* seg[] array doesn't contain specifications of the data buffers, but |
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* references to scsiif_request_segment arrays, which in turn reference the |
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* data buffers. While nr_segments holds the number of populated seg[] entries |
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* (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment |
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* elements referencing the target data buffers is calculated from the lengths |
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* of the seg[] elements (the sum of all valid seg[].length divided by the |
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* size of one scsiif_request_segment structure). |
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*/ |
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#define VSCSIIF_ACT_SCSI_CDB 1 |
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/* |
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* Request abort of a running operation for the specified target given by |
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* channel, id, lun and the operation's rqid in ref_rqid. |
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*/ |
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#define VSCSIIF_ACT_SCSI_ABORT 2 |
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/* |
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* Request a device reset of the specified target (channel and id). |
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*/ |
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#define VSCSIIF_ACT_SCSI_RESET 3 |
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/* |
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* Preset scatter/gather elements for a following request. Deprecated. |
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* Keeping the define only to avoid usage of the value "4" for other actions. |
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*/ |
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#define VSCSIIF_ACT_SCSI_SG_PRESET 4 |
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/* |
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* Maximum scatter/gather segments per request. |
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* |
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* Considering balance between allocating at least 16 "vscsiif_request" |
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* structures on one page (4096 bytes) and the number of scatter/gather |
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* elements needed, we decided to use 26 as a magic number. |
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* |
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* If "feature-sg-grant" is set, more scatter/gather elements can be specified |
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* by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages. |
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* In this case the vscsiif_request seg elements don't contain references to |
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* the user data, but to the SG elements referencing the user data. |
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*/ |
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#define VSCSIIF_SG_TABLESIZE 26 |
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/* |
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* based on Linux kernel 2.6.18, still valid |
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* Changing these values requires support of multiple protocols via the rings |
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* as "old clients" will blindly use these values and the resulting structure |
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* sizes. |
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*/ |
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#define VSCSIIF_MAX_COMMAND_SIZE 16 |
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#define VSCSIIF_SENSE_BUFFERSIZE 96 |
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struct scsiif_request_segment { |
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grant_ref_t gref; |
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uint16_t offset; |
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uint16_t length; |
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}; |
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#define VSCSIIF_SG_PER_PAGE (PAGE_SIZE / sizeof(struct scsiif_request_segment)) |
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/* Size of one request is 252 bytes */ |
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struct vscsiif_request { |
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uint16_t rqid; /* private guest value, echoed in resp */ |
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uint8_t act; /* command between backend and frontend */ |
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uint8_t cmd_len; /* valid CDB bytes */ |
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uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */ |
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uint16_t timeout_per_command; /* deprecated */ |
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uint16_t channel, id, lun; /* (virtual) device specification */ |
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uint16_t ref_rqid; /* command abort reference */ |
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uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1) |
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DMA_FROM_DEVICE(2) |
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DMA_NONE(3) requests */ |
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uint8_t nr_segments; /* Number of pieces of scatter-gather */ |
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/* |
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* flag in nr_segments: SG elements via grant page |
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* |
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* If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number |
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* of grant pages containing SG elements. Usable if "feature-sg-grant" set. |
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*/ |
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#define VSCSIIF_SG_GRANT 0x80 |
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struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; |
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uint32_t reserved[3]; |
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}; |
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/* Size of one response is 252 bytes */ |
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struct vscsiif_response { |
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uint16_t rqid; /* identifies request */ |
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uint8_t padding; |
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uint8_t sense_len; |
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uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE]; |
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int32_t rslt; |
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uint32_t residual_len; /* request bufflen - |
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return the value from physical device */ |
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uint32_t reserved[36]; |
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}; |
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DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); |
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#endif /*__XEN__PUBLIC_IO_SCSI_H__*/
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