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xen: Add essential and required interface headers

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Add essential and required Xen interface headers only taken from
the stable Linux kernel stable/linux-5.7.y at commit
66dfe4522160 Linux 5.7.5.

These are better suited for U-boot than the original headers
from Xen as they are the stripped versions of the same.

At the same time use public protocols from Xen RELEASE-4.13.1, at
commit 6278553325a9 update Xen version to 4.13.1
as those have more comments in them.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
Acked-by: Peng Fan <peng.fan@nxp.com>
This commit is contained in:
Oleksandr Andrushchenko 2020-08-06 12:42:46 +03:00 • committed by Tom Rini
parent 751897301d
commit 365d88ac7e
14 changed files with 3242 additions and 0 deletions
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701
include/xen/interface/io/blkif.h Normal file
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/* SPDX-License-Identifier: MIT
*
* blkif.h
*
* Unified block-device I/O interface for Xen guest OSes.
*
* Copyright (c) 2003-2004, Keir Fraser
* Copyright (c) 2012, Spectra Logic Corporation
*/
#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 u16
#endif
#define blkif_sector_t u64
/*
* Feature and Parameter Negotiation
* =================================
* The two halves of a Xen block driver utilize nodes within the XenStore to
* communicate capabilities and to negotiate operating parameters. This
* section enumerates these nodes which reside in the respective front and
* backend portions of the XenStore, following the XenBus convention.
*
* All data in the XenStore is stored as strings. Nodes specifying numeric
* values are encoded in decimal. Integer value ranges listed below are
* expressed as fixed sized integer types capable of storing the conversion
* of a properly formated node string, without loss of information.
*
* Any specified default value is in effect if the corresponding XenBus node
* is not present in the XenStore.
*
* XenStore nodes in sections marked "PRIVATE" are solely for use by the
* driver side whose XenBus tree contains them.
*
* XenStore nodes marked "DEPRECATED" in their notes section should only be
* used to provide interoperability with legacy implementations.
*
* See the XenBus state transition diagram below for details on when XenBus
* nodes must be published and when they can be queried.
*
*****************************************************************************
* Backend XenBus Nodes
*****************************************************************************
*
*------------------ Backend Device Identification (PRIVATE) ------------------
*
* mode
* Values: "r" (read only), "w" (writable)
*
* The read or write access permissions to the backing store to be
* granted to the frontend.
*
* params
* Values: string
*
* A free formatted string providing sufficient information for the
* hotplug script to attach the device and provide a suitable
* handler (ie: a block device) for blkback to use.
*
* physical-device
* Values: "MAJOR:MINOR"
* Notes: 11
*
* MAJOR and MINOR are the major number and minor number of the
* backing device respectively.
*
* physical-device-path
* Values: path string
*
* A string that contains the absolute path to the disk image. On
* NetBSD and Linux this is always a block device, while on FreeBSD
* it can be either a block device or a regular file.
*
* type
* Values: "file", "phy", "tap"
*
* The type of the backing device/object.
*
*
* direct-io-safe
* Values: 0/1 (boolean)
* Default Value: 0
*
* The underlying storage is not affected by the direct IO memory
* lifetime bug. See:
* http://lists.xen.org/archives/html/xen-devel/2012-12/msg01154.html
*
* Therefore this option gives the backend permission to use
* O_DIRECT, notwithstanding that bug.
*
* That is, if this option is enabled, use of O_DIRECT is safe,
* in circumstances where we would normally have avoided it as a
* workaround for that bug. This option is not relevant for all
* backends, and even not necessarily supported for those for
* which it is relevant. A backend which knows that it is not
* affected by the bug can ignore this option.
*
* This option doesn't require a backend to use O_DIRECT, so it
* should not be used to try to control the caching behaviour.
*
*--------------------------------- Features ---------------------------------
*
* feature-barrier
* Values: 0/1 (boolean)
* Default Value: 0
*
* A value of "1" indicates that the backend can process requests
* containing the BLKIF_OP_WRITE_BARRIER request opcode. Requests
* of this type may still be returned at any time with the
* BLKIF_RSP_EOPNOTSUPP result code.
*
* feature-flush-cache
* Values: 0/1 (boolean)
* Default Value: 0
*
* A value of "1" indicates that the backend can process requests
* containing the BLKIF_OP_FLUSH_DISKCACHE request opcode. Requests
* of this type may still be returned at any time with the
* BLKIF_RSP_EOPNOTSUPP result code.
*
* feature-discard
* Values: 0/1 (boolean)
* Default Value: 0
*
* A value of "1" indicates that the backend can process requests
* containing the BLKIF_OP_DISCARD request opcode. Requests
* of this type may still be returned at any time with the
* BLKIF_RSP_EOPNOTSUPP result code.
*
* feature-persistent
* Values: 0/1 (boolean)
* Default Value: 0
* Notes: 7
*
* A value of "1" indicates that the backend can keep the grants used
* by the frontend driver mapped, so the same set of grants should be
* used in all transactions. The maximum number of grants the backend
* can map persistently depends on the implementation, but ideally it
* should be RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST. Using this
* feature the backend doesn't need to unmap each grant, preventing
* costly TLB flushes. The backend driver should only map grants
* persistently if the frontend supports it. If a backend driver chooses
* to use the persistent protocol when the frontend doesn't support it,
* it will probably hit the maximum number of persistently mapped grants
* (due to the fact that the frontend won't be reusing the same grants),
* and fall back to non-persistent mode. Backend implementations may
* shrink or expand the number of persistently mapped grants without
* notifying the frontend depending on memory constraints (this might
* cause a performance degradation).
*
* If a backend driver wants to limit the maximum number of persistently
* mapped grants to a value less than RING_SIZE *
* BLKIF_MAX_SEGMENTS_PER_REQUEST a LRU strategy should be used to
* discard the grants that are less commonly used. Using a LRU in the
* backend driver paired with a LIFO queue in the frontend will
* allow us to have better performance in this scenario.
*
*----------------------- Request Transport Parameters ------------------------
*
* max-ring-page-order
* Values: <uint32_t>
* Default Value: 0
* Notes: 1, 3
*
* The maximum supported size of the request ring buffer in units of
* lb(machine pages). (e.g. 0 == 1 page, 1 = 2 pages, 2 == 4 pages,
* etc.).
*
* max-ring-pages
* Values: <uint32_t>
* Default Value: 1
* Notes: DEPRECATED, 2, 3
*
* The maximum supported size of the request ring buffer in units of
* machine pages. The value must be a power of 2.
*
*------------------------- Backend Device Properties -------------------------
*
* discard-enable
* Values: 0/1 (boolean)
* Default Value: 1
*
* This optional property, set by the toolstack, instructs the backend
* to offer (or not to offer) discard to the frontend. If the property
* is missing the backend should offer discard if the backing storage
* actually supports it.
*
* discard-alignment
* Values: <uint32_t>
* Default Value: 0
* Notes: 4, 5
*
* The offset, in bytes from the beginning of the virtual block device,
* to the first, addressable, discard extent on the underlying device.
*
* discard-granularity
* Values: <uint32_t>
* Default Value: <"sector-size">
* Notes: 4
*
* The size, in bytes, of the individually addressable discard extents
* of the underlying device.
*
* discard-secure
* Values: 0/1 (boolean)
* Default Value: 0
* Notes: 10
*
* A value of "1" indicates that the backend can process BLKIF_OP_DISCARD
* requests with the BLKIF_DISCARD_SECURE flag set.
*
* info
* Values: <uint32_t> (bitmap)
*
* A collection of bit flags describing attributes of the backing
* device. The VDISK_* macros define the meaning of each bit
* location.
*
* sector-size
* Values: <uint32_t>
*
* The logical block size, in bytes, of the underlying storage. This
* must be a power of two with a minimum value of 512.
*
* NOTE: Because of implementation bugs in some frontends this must be
* set to 512, unless the frontend advertizes a non-zero value
* in its "feature-large-sector-size" xenbus node. (See below).
*
* physical-sector-size
* Values: <uint32_t>
* Default Value: <"sector-size">
*
* The physical block size, in bytes, of the backend storage. This
* must be an integer multiple of "sector-size".
*
* sectors
* Values: <u64>
*
* The size of the backend device, expressed in units of "sector-size".
* The product of "sector-size" and "sectors" must also be an integer
* multiple of "physical-sector-size", if that node is present.
*
*****************************************************************************
* Frontend XenBus Nodes
*****************************************************************************
*
*----------------------- Request Transport Parameters -----------------------
*
* event-channel
* Values: <uint32_t>
*
* The identifier of the Xen event channel used to signal activity
* in the ring buffer.
*
* ring-ref
* Values: <uint32_t>
* Notes: 6
*
* The Xen grant reference granting permission for the backend to map
* the sole page in a single page sized ring buffer.
*
* ring-ref%u
* Values: <uint32_t>
* Notes: 6
*
* For a frontend providing a multi-page ring, a "number of ring pages"
* sized list of nodes, each containing a Xen grant reference granting
* permission for the backend to map the page of the ring located
* at page index "%u". Page indexes are zero based.
*
* protocol
* Values: string (XEN_IO_PROTO_ABI_*)
* Default Value: XEN_IO_PROTO_ABI_NATIVE
*
* The machine ABI rules governing the format of all ring request and
* response structures.
*
* ring-page-order
* Values: <uint32_t>
* Default Value: 0
* Maximum Value: MAX(ffs(max-ring-pages) - 1, max-ring-page-order)
* Notes: 1, 3
*
* The size of the frontend allocated request ring buffer in units
* of lb(machine pages). (e.g. 0 == 1 page, 1 = 2 pages, 2 == 4 pages,
* etc.).
*
* num-ring-pages
* Values: <uint32_t>
* Default Value: 1
* Maximum Value: MAX(max-ring-pages,(0x1 << max-ring-page-order))
* Notes: DEPRECATED, 2, 3
*
* The size of the frontend allocated request ring buffer in units of
* machine pages. The value must be a power of 2.
*
*--------------------------------- Features ---------------------------------
*
* feature-persistent
* Values: 0/1 (boolean)
* Default Value: 0
* Notes: 7, 8, 9
*
* A value of "1" indicates that the frontend will reuse the same grants
* for all transactions, allowing the backend to map them with write
* access (even when it should be read-only). If the frontend hits the
* maximum number of allowed persistently mapped grants, it can fallback
* to non persistent mode. This will cause a performance degradation,
* since the the backend driver will still try to map those grants
* persistently. Since the persistent grants protocol is compatible with
* the previous protocol, a frontend driver can choose to work in
* persistent mode even when the backend doesn't support it.
*
* It is recommended that the frontend driver stores the persistently
* mapped grants in a LIFO queue, so a subset of all persistently mapped
* grants gets used commonly. This is done in case the backend driver
* decides to limit the maximum number of persistently mapped grants
* to a value less than RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST.
*
* feature-large-sector-size
* Values: 0/1 (boolean)
* Default Value: 0
*
* A value of "1" indicates that the frontend will correctly supply and
* interpret all sector-based quantities in terms of the "sector-size"
* value supplied in the backend info, whatever that may be set to.
* If this node is not present or its value is "0" then it is assumed
* that the frontend requires that the logical block size is 512 as it
* is hardcoded (which is the case in some frontend implementations).
*
*------------------------- Virtual Device Properties -------------------------
*
* device-type
* Values: "disk", "cdrom", "floppy", etc.
*
* virtual-device
* Values: <uint32_t>
*
* A value indicating the physical device to virtualize within the
* frontend's domain. (e.g. "The first ATA disk", "The third SCSI
* disk", etc.)
*
* See docs/misc/vbd-interface.txt for details on the format of this
* value.
*
* Notes
* -----
* (1) Multi-page ring buffer scheme first developed in the Citrix XenServer
* PV drivers.
* (2) Multi-page ring buffer scheme first used in some RedHat distributions
* including a distribution deployed on certain nodes of the Amazon
* EC2 cluster.
* (3) Support for multi-page ring buffers was implemented independently,
* in slightly different forms, by both Citrix and RedHat/Amazon.
* For full interoperability, block front and backends should publish
* identical ring parameters, adjusted for unit differences, to the
* XenStore nodes used in both schemes.
* (4) Devices that support discard functionality may internally allocate space
* (discardable extents) in units that are larger than the exported logical
* block size. If the backing device has such discardable extents the
* backend should provide both discard-granularity and discard-alignment.
* Providing just one of the two may be considered an error by the frontend.
* Backends supporting discard should include discard-granularity and
* discard-alignment even if it supports discarding individual sectors.
* Frontends should assume discard-alignment == 0 and discard-granularity
* == sector size if these keys are missing.
* (5) The discard-alignment parameter allows a physical device to be
* partitioned into virtual devices that do not necessarily begin or
* end on a discardable extent boundary.
* (6) When there is only a single page allocated to the request ring,
* 'ring-ref' is used to communicate the grant reference for this
* page to the backend. When using a multi-page ring, the 'ring-ref'
* node is not created. Instead 'ring-ref0' - 'ring-refN' are used.
* (7) When using persistent grants data has to be copied from/to the page
* where the grant is currently mapped. The overhead of doing this copy
* however doesn't suppress the speed improvement of not having to unmap
* the grants.
* (8) The frontend driver has to allow the backend driver to map all grants
* with write access, even when they should be mapped read-only, since
* further requests may reuse these grants and require write permissions.
* (9) Linux implementation doesn't have a limit on the maximum number of
* grants that can be persistently mapped in the frontend driver, but
* due to the frontent driver implementation it should never be bigger
* than RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST.
*(10) The discard-secure property may be present and will be set to 1 if the
* backing device supports secure discard.
*(11) Only used by Linux and NetBSD.
*/
/*
* Multiple hardware queues/rings:
* If supported, the backend will write the key "multi-queue-max-queues" to
* the directory for that vbd, and set its value to the maximum supported
* number of queues.
* Frontends that are aware of this feature and wish to use it can write the
* key "multi-queue-num-queues" with the number they wish to use, which must be
* greater than zero, and no more than the value reported by the backend in
* "multi-queue-max-queues".
*
* For frontends requesting just one queue, the usual event-channel and
* ring-ref keys are written as before, simplifying the backend processing
* to avoid distinguishing between a frontend that doesn't understand the
* multi-queue feature, and one that does, but requested only one queue.
*
* Frontends requesting two or more queues must not write the toplevel
* event-channel and ring-ref keys, instead writing those keys under sub-keys
* having the name "queue-N" where N is the integer ID of the queue/ring for
* which those keys belong. Queues are indexed from zero.
* For example, a frontend with two queues must write the following set of
* queue-related keys:
*
* /local/domain/1/device/vbd/0/multi-queue-num-queues = "2"
* /local/domain/1/device/vbd/0/queue-0 = ""
* /local/domain/1/device/vbd/0/queue-0/ring-ref = "<ring-ref#0>"
* /local/domain/1/device/vbd/0/queue-0/event-channel = "<evtchn#0>"
* /local/domain/1/device/vbd/0/queue-1 = ""
* /local/domain/1/device/vbd/0/queue-1/ring-ref = "<ring-ref#1>"
* /local/domain/1/device/vbd/0/queue-1/event-channel = "<evtchn#1>"
*
* It is also possible to use multiple queues/rings together with
* feature multi-page ring buffer.
* For example, a frontend requests two queues/rings and the size of each ring
* buffer is two pages must write the following set of related keys:
*
* /local/domain/1/device/vbd/0/multi-queue-num-queues = "2"
* /local/domain/1/device/vbd/0/ring-page-order = "1"
* /local/domain/1/device/vbd/0/queue-0 = ""
* /local/domain/1/device/vbd/0/queue-0/ring-ref0 = "<ring-ref#0>"
* /local/domain/1/device/vbd/0/queue-0/ring-ref1 = "<ring-ref#1>"
* /local/domain/1/device/vbd/0/queue-0/event-channel = "<evtchn#0>"
* /local/domain/1/device/vbd/0/queue-1 = ""
* /local/domain/1/device/vbd/0/queue-1/ring-ref0 = "<ring-ref#2>"
* /local/domain/1/device/vbd/0/queue-1/ring-ref1 = "<ring-ref#3>"
* /local/domain/1/device/vbd/0/queue-1/event-channel = "<evtchn#1>"
*
*/
/*
* STATE DIAGRAMS
*
*****************************************************************************
* Startup *
*****************************************************************************
*
* Tool stack creates front and back nodes with state XenbusStateInitialising.
*
* Front Back
* ================================= =====================================
* XenbusStateInitialising XenbusStateInitialising
* o Query virtual device o Query backend device identification
* properties. data.
* o Setup OS device instance. o Open and validate backend device.
* o Publish backend features and
* transport parameters.
* |
* |
* V
* XenbusStateInitWait
*
* o Query backend features and
* transport parameters.
* o Allocate and initialize the
* request ring.
* o Publish transport parameters
* that will be in effect during
* this connection.
* |
* |
* V
* XenbusStateInitialised
*
* o Query frontend transport parameters.
* o Connect to the request ring and
* event channel.
* o Publish backend device properties.
* |
* |
* V
* XenbusStateConnected
*
* o Query backend device properties.
* o Finalize OS virtual device
* instance.
* |
* |
* V
* XenbusStateConnected
*
* Note: Drivers that do not support any optional features, or the negotiation
* of transport parameters, can skip certain states in the state machine:
*
* o A frontend may transition to XenbusStateInitialised without
* waiting for the backend to enter XenbusStateInitWait. In this
* case, default transport parameters are in effect and any
* transport parameters published by the frontend must contain
* their default values.
*
* o A backend may transition to XenbusStateInitialised, bypassing
* XenbusStateInitWait, without waiting for the frontend to first
* enter the XenbusStateInitialised state. In this case, default
* transport parameters are in effect and any transport parameters
* published by the backend must contain their default values.
*
* Drivers that support optional features and/or transport parameter
* negotiation must tolerate these additional state transition paths.
* In general this means performing the work of any skipped state
* transition, if it has not already been performed, in addition to the
* work associated with entry into the current state.
*/
/*
* REQUEST CODES.
*/
#define BLKIF_OP_READ 0
#define BLKIF_OP_WRITE 1
/*
* All writes issued prior to a request with the BLKIF_OP_WRITE_BARRIER
* operation code ("barrier request") must be completed prior to the
* execution of the barrier request. All writes issued after the barrier
* request must not execute until after the completion of the barrier request.
*
* Optional. See "feature-barrier" XenBus node documentation above.
*/
#define BLKIF_OP_WRITE_BARRIER 2
/*
* Commit any uncommitted contents of the backing device's volatile cache
* to stable storage.
*
* Optional. See "feature-flush-cache" XenBus node documentation above.
*/
#define BLKIF_OP_FLUSH_DISKCACHE 3
/*
* Used in SLES sources for device specific command packet
* contained within the request. Reserved for that purpose.
*/
#define BLKIF_OP_RESERVED_1 4
/*
* Indicate to the backend device that a region of storage is no longer in
* use, and may be discarded at any time without impact to the client. If
* the BLKIF_DISCARD_SECURE flag is set on the request, all copies of the
* discarded region on the device must be rendered unrecoverable before the
* command returns.
*
* This operation is analogous to performing a trim (ATA) or unamp (SCSI),
* command on a native device.
*
* More information about trim/unmap operations can be found at:
* http://t13.org/Documents/UploadedDocuments/docs2008/
* e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
* http://www.seagate.com/staticfiles/support/disc/manuals/
* Interface%20manuals/100293068c.pdf
*
* Optional. See "feature-discard", "discard-alignment",
* "discard-granularity", and "discard-secure" in the XenBus node
* documentation above.
*/
#define BLKIF_OP_DISCARD 5
/*
* Recognized if "feature-max-indirect-segments" in present in the backend
* xenbus info. The "feature-max-indirect-segments" node contains the maximum
* number of segments allowed by the backend per request. If the node is
* present, the frontend might use blkif_request_indirect structs in order to
* issue requests with more than BLKIF_MAX_SEGMENTS_PER_REQUEST (11). The
* maximum number of indirect segments is fixed by the backend, but the
* frontend can issue requests with any number of indirect segments as long as
* it's less than the number provided by the backend. The indirect_grefs field
* in blkif_request_indirect should be filled by the frontend with the
* grant references of the pages that are holding the indirect segments.
* These pages are filled with an array of blkif_request_segment that hold the
* information about the segments. The number of indirect pages to use is
* determined by the number of segments an indirect request contains. Every
* indirect page can contain a maximum of
* (PAGE_SIZE / sizeof(struct blkif_request_segment)) segments, so to
* calculate the number of indirect pages to use we have to do
* ceil(indirect_segments / (PAGE_SIZE / sizeof(struct blkif_request_segment))).
*
* If a backend does not recognize BLKIF_OP_INDIRECT, it should *not*
* create the "feature-max-indirect-segments" node!
*/
#define BLKIF_OP_INDIRECT 6
/*
* 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
/*
* Maximum number of indirect pages to use per request.
*/
#define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8
/*
* NB. 'first_sect' and 'last_sect' in blkif_request_segment, as well as
* 'sector_number' in blkif_request, blkif_request_discard and
* blkif_request_indirect are sector-based quantities. See the description
* of the "feature-large-sector-size" frontend xenbus node above for
* more information.
*/
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). */
u8 first_sect, last_sect;
};
/*
* Starting ring element for any I/O request.
*/
struct blkif_request {
u8 operation; /* BLKIF_OP_??? */
u8 nr_segments; /* number of segments */
blkif_vdev_t handle; /* only for read/write requests */
u64 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];
};
/*
* Cast to this structure when blkif_request.operation == BLKIF_OP_DISCARD
* sizeof(struct blkif_request_discard) <= sizeof(struct blkif_request)
*/
struct blkif_request_discard {
u8 operation; /* BLKIF_OP_DISCARD */
u8 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 */
u64 id; /* private guest value, echoed in resp */
blkif_sector_t sector_number;/* start sector idx on disk */
u64 nr_sectors; /* number of contiguous sectors to discard*/
};
struct blkif_request_indirect {
u8 operation; /* BLKIF_OP_INDIRECT */
u8 indirect_op; /* BLKIF_OP_{READ/WRITE} */
u16 nr_segments; /* number of segments */
u64 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 */
grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
#ifdef __i386__
u64 pad; /* Make it 64 byte aligned on i386 */
#endif
};
struct blkif_response {
u64 id; /* copied from request */
u8 operation; /* copied from request */
s16 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
#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/

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/* SPDX-License-Identifier: MIT
*
* console.h
*
* Console I/O interface for Xen guest OSes.
*
* Copyright (c) 2005, Keir Fraser
*/
#ifndef __XEN_PUBLIC_IO_CONSOLE_H__
#define __XEN_PUBLIC_IO_CONSOLE_H__
typedef u32 XENCONS_RING_IDX;
#define MASK_XENCONS_IDX(idx, ring) ((idx) & (sizeof(ring) - 1))
struct xencons_interface {
char in[1024];
char out[2048];
XENCONS_RING_IDX in_cons, in_prod;
XENCONS_RING_IDX out_cons, out_prod;
};
#ifdef XEN_WANT_FLEX_CONSOLE_RING
#include "ring.h"
DEFINE_XEN_FLEX_RING(xencons);
#endif
#endif /* __XEN_PUBLIC_IO_CONSOLE_H__ */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/

28
include/xen/interface/io/protocols.h Normal file
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/* SPDX-License-Identifier: MIT
*
* protocols.h
*
* Copyright (c) 2008, Keir Fraser
*
* Xen protocols, which are used as ABI rules governing the format of all
* ring request and response structures.
*/
#ifndef __XEN_PROTOCOLS_H__
#define __XEN_PROTOCOLS_H__
#define XEN_IO_PROTO_ABI_X86_32 "x86_32-abi"
#define XEN_IO_PROTO_ABI_X86_64 "x86_64-abi"
#define XEN_IO_PROTO_ABI_ARM "arm-abi"
#if defined(__i386__)
# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_32
#elif defined(__x86_64__)
# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_64
#elif defined(__arm__) || defined(__aarch64__)
# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_ARM
#else
# error arch fixup needed here
#endif
#endif

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/* SPDX-License-Identifier: MIT
*
* ring.h
*
* Shared producer-consumer ring macros.
*
* Tim Deegan and Andrew Warfield November 2004.
*/
#ifndef __XEN_PUBLIC_IO_RING_H__
#define __XEN_PUBLIC_IO_RING_H__
/*
* When #include'ing this header, you need to provide the following
* declaration upfront:
* - standard integers types (u8, u16, etc)
* They are provided by stdint.h of the standard headers.
*
* In addition, if you intend to use the FLEX macros, you also need to
* provide the following, before invoking the FLEX macros:
* - size_t
* - memcpy
* - grant_ref_t
* These declarations are provided by string.h of the standard headers,
* and grant_table.h from the Xen public headers.
*/
#include <xen/interface/grant_table.h>
typedef unsigned int RING_IDX;
/* Round a 32-bit unsigned constant down to the nearest power of two. */
#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x) >> 2) << 2 : __RD2(_x))
#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x) >> 4) << 4 : __RD4(_x))
#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x) >> 8) << 8 : __RD8(_x))
#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x) >> 16) << 16 : __RD16(_x))
/*
* Calculate size of a shared ring, given the total available space for the
* ring and indexes (_sz), and the name tag of the request/response structure.
* A ring contains as many entries as will fit, rounded down to the nearest
* power of two (so we can mask with (size-1) to loop around).
*/
#define __CONST_RING_SIZE(_s, _sz) \
(__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
sizeof(((struct _s##_sring *)0)->ring[0])))
/*
* The same for passing in an actual pointer instead of a name tag.
*/
#define __RING_SIZE(_s, _sz) \
(__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
/*
* Macros to make the correct C datatypes for a new kind of ring.
*
* To make a new ring datatype, you need to have two message structures,
* let's say request_t, and response_t already defined.
*
* In a header where you want the ring datatype declared, you then do:
*
* DEFINE_RING_TYPES(mytag, request_t, response_t);
*
* These expand out to give you a set of types, as you can see below.
* The most important of these are:
*
* mytag_sring_t - The shared ring.
* mytag_front_ring_t - The 'front' half of the ring.
* mytag_back_ring_t - The 'back' half of the ring.
*
* To initialize a ring in your code you need to know the location and size
* of the shared memory area (PAGE_SIZE, for instance). To initialise
* the front half:
*
* mytag_front_ring_t front_ring;
* SHARED_RING_INIT((mytag_sring_t *)shared_page);
* FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*
* Initializing the back follows similarly (note that only the front
* initializes the shared ring):
*
* mytag_back_ring_t back_ring;
* BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*/
#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
\
/* Shared ring entry */ \
union __name##_sring_entry { \
__req_t req; \
__rsp_t rsp; \
}; \
\
/* Shared ring page */ \
struct __name##_sring { \
RING_IDX req_prod, req_event; \
RING_IDX rsp_prod, rsp_event; \
union { \
struct { \
u8 smartpoll_active; \
} netif; \
struct { \
u8 msg; \
} tapif_user; \
u8 pvt_pad[4]; \
} pvt; \
u8 __pad[44]; \
union __name##_sring_entry ring[1]; /* variable-length */ \
}; \
\
/* "Front" end's private variables */ \
struct __name##_front_ring { \
RING_IDX req_prod_pvt; \
RING_IDX rsp_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
}; \
\
/* "Back" end's private variables */ \
struct __name##_back_ring { \
RING_IDX rsp_prod_pvt; \
RING_IDX req_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
}; \
\
/* Syntactic sugar */ \
typedef struct __name##_sring __name##_sring_t; \
typedef struct __name##_front_ring __name##_front_ring_t; \
typedef struct __name##_back_ring __name##_back_ring_t
/*
* Macros for manipulating rings.
*
* FRONT_RING_whatever works on the "front end" of a ring: here
* requests are pushed on to the ring and responses taken off it.
*
* BACK_RING_whatever works on the "back end" of a ring: here
* requests are taken off the ring and responses put on.
*
* N.B. these macros do NO INTERLOCKS OR FLOW CONTROL.
* This is OK in 1-for-1 request-response situations where the
* requestor (front end) never has more than RING_SIZE()-1
* outstanding requests.
*/
/* Initialising empty rings */
#define SHARED_RING_INIT(_s) do { \
(_s)->req_prod = (_s)->rsp_prod = 0; \
(_s)->req_event = (_s)->rsp_event = 1; \
(void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \
(void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \
} while (0)
#define FRONT_RING_INIT(_r, _s, __size) do { \
(_r)->req_prod_pvt = 0; \
(_r)->rsp_cons = 0; \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
} while (0)
#define BACK_RING_INIT(_r, _s, __size) do { \
(_r)->rsp_prod_pvt = 0; \
(_r)->req_cons = 0; \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
} while (0)
/* How big is this ring? */
#define RING_SIZE(_r) \
((_r)->nr_ents)
/* Number of free requests (for use on front side only). */
#define RING_FREE_REQUESTS(_r) \
(RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons))
/* Test if there is an empty slot available on the front ring.
* (This is only meaningful from the front. )
*/
#define RING_FULL(_r) \
(RING_FREE_REQUESTS(_r) == 0)
/* Test if there are outstanding messages to be processed on a ring. */
#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
((_r)->sring->rsp_prod - (_r)->rsp_cons)
#ifdef __GNUC__
#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \
unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
unsigned int rsp = RING_SIZE(_r) - \
((_r)->req_cons - (_r)->rsp_prod_pvt); \
req < rsp ? req : rsp; \
})
#else
/* Same as above, but without the nice GCC ({ ... }) syntax. */
#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
((((_r)->sring->req_prod - (_r)->req_cons) < \
(RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \
((_r)->sring->req_prod - (_r)->req_cons) : \
(RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt)))
#endif
/* Direct access to individual ring elements, by index. */
#define RING_GET_REQUEST(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
/*
* Get a local copy of a request.
*
* Use this in preference to RING_GET_REQUEST() so all processing is
* done on a local copy that cannot be modified by the other end.
*
* Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this
* to be ineffective where _req is a struct which consists of only bitfields.
*/
#define RING_COPY_REQUEST(_r, _idx, _req) do { \
/* Use volatile to force the copy into _req. */ \
*(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \
} while (0)
#define RING_GET_RESPONSE(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
/* Loop termination condition: Would the specified index overflow the ring? */
#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
/* Ill-behaved frontend determination: Can there be this many requests? */
#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
(((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
#define RING_PUSH_REQUESTS(_r) do { \
xen_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
} while (0)
#define RING_PUSH_RESPONSES(_r) do { \
xen_wmb(); /* front sees resps /before/ updated producer index */ \
(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
} while (0)
/*
* Notification hold-off (req_event and rsp_event):
*
* When queueing requests or responses on a shared ring, it may not always be
* necessary to notify the remote end. For example, if requests are in flight
* in a backend, the front may be able to queue further requests without
* notifying the back (if the back checks for new requests when it queues
* responses).
*
* When enqueuing requests or responses:
*
* Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument
* is a boolean return value. True indicates that the receiver requires an
* asynchronous notification.
*
* After dequeuing requests or responses (before sleeping the connection):
*
* Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES().
* The second argument is a boolean return value. True indicates that there
* are pending messages on the ring (i.e., the connection should not be put
* to sleep).
*
* These macros will set the req_event/rsp_event field to trigger a
* notification on the very next message that is enqueued. If you want to
* create batches of work (i.e., only receive a notification after several
* messages have been enqueued) then you will need to create a customised
* version of the FINAL_CHECK macro in your own code, which sets the event
* field appropriately.
*/
#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->req_prod; \
RING_IDX __new = (_r)->req_prod_pvt; \
xen_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = __new; \
xen_mb(); /* back sees new requests /before/ we check req_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->rsp_prod; \
RING_IDX __new = (_r)->rsp_prod_pvt; \
xen_wmb(); /* front sees resps /before/ updated producer index */ \
(_r)->sring->rsp_prod = __new; \
xen_mb(); /* front sees new resps /before/ we check rsp_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
if (_work_to_do) \
break; \
(_r)->sring->req_event = (_r)->req_cons + 1; \
xen_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
} while (0)
#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
if (_work_to_do) \
break; \
(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
xen_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)
/*
* DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and
* functions to check if there is data on the ring, and to read and
* write to them.
*
* DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but
* does not define the indexes page. As different protocols can have
* extensions to the basic format, this macro allow them to define their
* own struct.
*
* XEN_FLEX_RING_SIZE
* Convenience macro to calculate the size of one of the two rings
* from the overall order.
*
* $NAME_mask
* Function to apply the size mask to an index, to reduce the index
* within the range [0-size].
*
* $NAME_read_packet
* Function to read data from the ring. The amount of data to read is
* specified by the "size" argument.
*
* $NAME_write_packet
* Function to write data to the ring. The amount of data to write is
* specified by the "size" argument.
*
* $NAME_get_ring_ptr
* Convenience function that returns a pointer to read/write to the
* ring at the right location.
*
* $NAME_data_intf
* Indexes page, shared between frontend and backend. It also
* contains the array of grant refs.
*
* $NAME_queued
* Function to calculate how many bytes are currently on the ring,
* ready to be read. It can also be used to calculate how much free
* space is currently on the ring (XEN_FLEX_RING_SIZE() -
* $NAME_queued()).
*/
#ifndef XEN_PAGE_SHIFT
/* The PAGE_SIZE for ring protocols and hypercall interfaces is always
* 4K, regardless of the architecture, and page granularity chosen by
* operating systems.
*/
#define XEN_PAGE_SHIFT 12
#endif
#define XEN_FLEX_RING_SIZE(order) \
(1UL << ((order) + XEN_PAGE_SHIFT - 1))
#define DEFINE_XEN_FLEX_RING(name) \
static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \
{ \
return idx & (ring_size - 1); \
} \
\
static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \
RING_IDX idx, \
RING_IDX ring_size) \
{ \
return buf + name##_mask(idx, ring_size); \
} \
\
static inline void name##_read_packet(void *opaque, \
const unsigned char *buf, \
size_t size, \
RING_IDX masked_prod, \
RING_IDX *masked_cons, \
RING_IDX ring_size) \
{ \
if (*masked_cons < masked_prod || \
size <= ring_size - *masked_cons) { \
memcpy(opaque, buf + *masked_cons, size); \
} else { \
memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \
memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \
size - (ring_size - *masked_cons)); \
} \
*masked_cons = name##_mask(*masked_cons + size, ring_size); \
} \
\
static inline void name##_write_packet(unsigned char *buf, \
const void *opaque, \
size_t size, \
RING_IDX *masked_prod, \
RING_IDX masked_cons, \
RING_IDX ring_size) \
{ \
if (*masked_prod < masked_cons || \
size <= ring_size - *masked_prod) { \
memcpy(buf + *masked_prod, opaque, size); \
} else { \
memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \
memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \
size - (ring_size - *masked_prod)); \
} \
*masked_prod = name##_mask(*masked_prod + size, ring_size); \
} \
\
static inline RING_IDX name##_queued(RING_IDX prod, \
RING_IDX cons, \
RING_IDX ring_size) \
{ \
RING_IDX size; \
\
if (prod == cons) \
return 0; \
\
prod = name##_mask(prod, ring_size); \
cons = name##_mask(cons, ring_size); \
\
if (prod == cons) \
return ring_size; \
\
if (prod > cons) \
size = prod - cons; \
else \
size = ring_size - (cons - prod); \
return size; \
} \
\
struct name##_data { \
unsigned char *in; /* half of the allocation */ \
unsigned char *out; /* half of the allocation */ \
}
#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \
struct name##_data_intf { \
RING_IDX in_cons, in_prod; \
\
u8 pad1[56]; \
\
RING_IDX out_cons, out_prod; \
\
u8 pad2[56]; \
\
RING_IDX ring_order; \
grant_ref_t ref[]; \
}; \
DEFINE_XEN_FLEX_RING(name)
#endif /* __XEN_PUBLIC_IO_RING_H__ */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*/

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/* SPDX-License-Identifier: MIT
*
* xenbus.h
*
* Xenbus protocol details.
*
* Copyright (C) 2005 XenSource Ltd.
*/
#ifndef _XEN_PUBLIC_IO_XENBUS_H
#define _XEN_PUBLIC_IO_XENBUS_H
/*
* The state of either end of the Xenbus, i.e. the current communication
* status of initialisation across the bus. States here imply nothing about
* the state of the connection between the driver and the kernel's device
* layers.
*/
enum xenbus_state {
XenbusStateUnknown = 0,
XenbusStateInitialising = 1,
/*
* InitWait: Finished early initialisation but waiting for information
* from the peer or hotplug scripts.
*/
XenbusStateInitWait = 2,
/*
* Initialised: Waiting for a connection from the peer.
*/
XenbusStateInitialised = 3,
XenbusStateConnected = 4,
/*
* Closing: The device is being closed due to an error or an unplug event.
*/
XenbusStateClosing = 5,
XenbusStateClosed = 6,
/*
* Reconfiguring: The device is being reconfigured.
*/
XenbusStateReconfiguring = 7,
XenbusStateReconfigured = 8
};
typedef enum xenbus_state XenbusState;
#endif /* _XEN_PUBLIC_IO_XENBUS_H */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/

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/* SPDX-License-Identifier: MIT
*
* Details of the "wire" protocol between Xen Store Daemon and client
* library or guest kernel.
*
* Copyright (C) 2005 Rusty Russell IBM Corporation
*/
#ifndef _XS_WIRE_H
#define _XS_WIRE_H
enum xsd_sockmsg_type {
XS_CONTROL,
#define XS_DEBUG XS_CONTROL
XS_DIRECTORY,
XS_READ,
XS_GET_PERMS,
XS_WATCH,
XS_UNWATCH,
XS_TRANSACTION_START,
XS_TRANSACTION_END,
XS_INTRODUCE,
XS_RELEASE,
XS_GET_DOMAIN_PATH,
XS_WRITE,
XS_MKDIR,
XS_RM,
XS_SET_PERMS,
XS_WATCH_EVENT,
XS_ERROR,
XS_IS_DOMAIN_INTRODUCED,
XS_RESUME,
XS_SET_TARGET,
/* XS_RESTRICT has been removed */
XS_RESET_WATCHES = XS_SET_TARGET + 2,
XS_DIRECTORY_PART,
XS_TYPE_COUNT, /* Number of valid types. */
XS_INVALID = 0xffff /* Guaranteed to remain an invalid type */
};
#define XS_WRITE_NONE "NONE"
#define XS_WRITE_CREATE "CREATE"
#define XS_WRITE_CREATE_EXCL "CREATE|EXCL"
/* We hand errors as strings, for portability. */
struct xsd_errors {
int errnum;
const char *errstring;
};
#ifdef EINVAL
#define XSD_ERROR(x) { x, #x }
/* LINTED: static unused */
static struct xsd_errors xsd_errors[]
#if defined(__GNUC__)
__attribute__((unused))
#endif
= {
XSD_ERROR(EINVAL),
XSD_ERROR(EACCES),
XSD_ERROR(EEXIST),
XSD_ERROR(EISDIR),
XSD_ERROR(ENOENT),
XSD_ERROR(ENOMEM),
XSD_ERROR(ENOSPC),
XSD_ERROR(EIO),
XSD_ERROR(ENOTEMPTY),
XSD_ERROR(ENOSYS),
XSD_ERROR(EROFS),
XSD_ERROR(EBUSY),
XSD_ERROR(EAGAIN),
XSD_ERROR(EISCONN),
XSD_ERROR(E2BIG)
};
#endif
struct xsd_sockmsg {
u32 type; /* XS_??? */
u32 req_id;/* Request identifier, echoed in daemon's response. */
u32 tx_id; /* Transaction id (0 if not related to a transaction). */
u32 len; /* Length of data following this. */
/* Generally followed by nul-terminated string(s). */
};
enum xs_watch_type {
XS_WATCH_PATH = 0,
XS_WATCH_TOKEN
};
/*
* `incontents 150 xenstore_struct XenStore wire protocol.
*
* Inter-domain shared memory communications.
*/
#define XENSTORE_RING_SIZE 1024
typedef u32 XENSTORE_RING_IDX;
#define MASK_XENSTORE_IDX(idx) ((idx) & (XENSTORE_RING_SIZE - 1))
struct xenstore_domain_interface {
char req[XENSTORE_RING_SIZE]; /* Requests to xenstore daemon. */
char rsp[XENSTORE_RING_SIZE]; /* Replies and async watch events. */
XENSTORE_RING_IDX req_cons, req_prod;
XENSTORE_RING_IDX rsp_cons, rsp_prod;
u32 server_features; /* Bitmap of features supported by the server */
u32 connection;
};
/* Violating this is very bad. See docs/misc/xenstore.txt. */
#define XENSTORE_PAYLOAD_MAX 4096
/* Violating these just gets you an error back */
#define XENSTORE_ABS_PATH_MAX 3072
#define XENSTORE_REL_PATH_MAX 2048
/* The ability to reconnect a ring */
#define XENSTORE_SERVER_FEATURE_RECONNECTION 1
/* Valid values for the connection field */
#define XENSTORE_CONNECTED 0 /* the steady-state */
#define XENSTORE_RECONNECT 1 /* guest has initiated a reconnect */
#endif /* _XS_WIRE_H */
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*/