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Message-Id: <1328439694-18705-1-git-send-email-pbonzini@redhat.com>
Date: Sun, 5 Feb 2012 12:01:34 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Rusty Russell <rusty@...tcorp.com.au>,
virtualization <virtualization@...ts.linux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Stefan Hajnoczi <stefanha@...ux.vnet.ibm.com>,
linux-scsi <linux-scsi@...r.kernel.org>
Subject: [PATCH v3] Add virtio-scsi to the virtio spec
Hi Rusty,
here is the specification for a virtio-based SCSI host (controller, HBA,
you name it) so that you can apply it to the spec document and publish it.
I changed the index from 7 to 8 to account for the rpmsg device,
and added a feature bit to tell the guest in advance whether the host
supports hotplug. Otherwise there is no change from v2.
Paolo
--- virtio-spec.lyx.saved 2011-11-29 14:00:59.782659120 +0100
+++ virtio-spec.lyx 2012-02-05 11:57:34.691711427 +0100
@@ -56,6 +56,7 @@
\html_math_output 0
\html_css_as_file 0
\html_be_strict false
+\author 1531152142 "pbonzini"
\end_header
\begin_body
@@ -321,7 +322,7 @@
\begin_layout Standard
\begin_inset Tabular
-<lyxtabular version="3" rows="8" columns="3">
+<lyxtabular version="3" rows="9" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
@@ -530,8 +531,43 @@
</cell>
</row>
<row>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1328438958
+8
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322650855
+SCSI host
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322650861
+Appendix H
+\end_layout
+
+\end_inset
+</cell>
+</row>
+<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
9
@@ -6427,6 +6463,2188 @@
\end_layout
\begin_layout Chapter*
+
+\change_inserted 1531152142 1322571716
+Appendix H: SCSI Host Device
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1323090161
+The virtio SCSI host device groups together one or more virtual logical
+ units (such as disks), and allows communicating to them using the SCSI
+ protocol.
+ An instance of the device represents a SCSI host to which many targets
+ and LUNs are attached.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322571726
+The virtio SCSI device services two kinds of requests:
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322571726
+command requests for a logical unit;
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322571726
+task management functions related to a logical unit, target or command.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322571726
+The device is also able to send out notifications about added and removed
+ logical units.
+ Together, these capabilities provide a SCSI transport protocol that uses
+ virtqueues as the transfer medium.
+ In the transport protocol, the virtio driver acts as the initiator, while
+ the virtio SCSI host provides one or more targets that receive and process
+ the requests.
+
+\end_layout
+
+\begin_layout Section*
+
+\change_inserted 1531152142 1322571697
+Configuration
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322651166
+Subsystem
+\begin_inset space ~
+\end_inset
+
+Device
+\begin_inset space ~
+\end_inset
+
+ID 7
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322571777
+Virtqueues 0:controlq; 1:eventq; 2..n:request queues.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322571813
+Feature
+\begin_inset space ~
+\end_inset
+
+bits
+\end_layout
+
+\begin_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1328438975
+VIRTIO_SCSI_F_INOUT
+\begin_inset space ~
+\end_inset
+
+(0) A single request can include both read-only and write-only data buffers.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1328439056
+VIRTIO_SCSI_F_HOTPLUG
+\begin_inset space ~
+\end_inset
+
+(1) The host should enable hot-plug/hot-unplug of new LUNs and targets on
+ the SCSI bus.
+\end_layout
+
+\end_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322651190
+Device
+\begin_inset space ~
+\end_inset
+
+configuration
+\begin_inset space ~
+\end_inset
+
+layout All fields of this configuration are always available.
+
+\series bold
+sense_size
+\series default
+ and
+\series bold
+cdb_size
+\series default
+ are writable by the guest.
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322571919
+
+struct virtio_scsi_config {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575810
+
+ u32 num_queues;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322934205
+
+ u32 seg_max;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322934257
+
+ u32 max_sectors;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322934350
+
+ u32 cmd_per_lun;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575811
+
+ u32 event_info_size;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575811
+
+ u32 sense_size;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575812
+
+ u32 cdb_size;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322576412
+
+ u16 max_channel;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322576413
+
+ u16 max_target;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322576414
+
+ u32 max_lun;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322571878
+
+};
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322724976
+num_queues is the total number of request virtqueues exposed by the device.
+ The driver is free to use only one request queue, or it can use more to
+ achieve better performance.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322934245
+seg_max is the maximum number of segments that can be in a command.
+ A bidirectional command can include
+\series bold
+seg_max
+\series default
+ input segments and
+\series bold
+seg_max
+\series default
+output segments.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322934739
+max_sectors is a hint to the guest about the maximum transfer size it should
+ use.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322934845
+cmd_per_lun is a hint to the guest about the maximum number of linked commands
+ it should send to one LUN.
+ The actual value to be used is the minimum of
+\series bold
+cmd_per_lun
+\series default
+ and the virtqueue size.
+\change_unchanged
+
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322571959
+event_info_size is the maximum size that the device will fill for buffers
+ that the driver places in the eventq.
+ The driver should always put buffers at least of this size.
+ It is written by the device depending on the set of negotated features.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322571997
+sense_size is the maximum size of the sense data that the device will write.
+ The default value is written by the device and will always be 96, but the
+ driver can modify it.
+ It is restored to the default when the device is reset.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322575599
+cdb_size is the maximum size of the CDB that the driver will write.
+ The default value is written by the device and will always be 32, but the
+ driver can likewise modify it.
+ It is restored to the default when the device is reset.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322724997
+max_channel,
+\begin_inset space \space{}
+\end_inset
+
+max_target
+\series medium
+
+\begin_inset space ~
+\end_inset
+
+and
+\begin_inset space \space{}
+\end_inset
+
+
+\series default
+max_lun can be used by the driver as hints to constrain scanning the logical
+ units on the host.
+\change_unchanged
+
+\end_layout
+
+\end_deeper
+\begin_layout Section*
+
+\change_inserted 1531152142 1322571959
+Device Initialization
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572042
+The initialization routine should first of all discover the device's virtqueues.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572054
+If the driver uses the eventq, it should then place at least a buffer in
+ the eventq.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572042
+The driver can immediately issue requests (for example, INQUIRY or REPORT
+ LUNS) or task management functions (for example, I_T RESET).
+
+\end_layout
+
+\begin_layout Section*
+
+\change_inserted 1531152142 1322572348
+Device Operation: request queues
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322725031
+The driver queues requests to an arbitrary request queue, and they are used
+ by the device on that same queue.
+ It is the responsibility of the driver to ensure strict request ordering
+ for commands placed on different queues, because they will be consumed
+ with no order constraints.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572395
+Requests have the following format:
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572526
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725766
+
+struct virtio_scsi_req_cmd {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725783
+
+ // Read-only
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572417
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572419
+
+ u64 id;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572420
+
+ u8 task_attr;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572422
+
+ u8 prio;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572425
+
+ u8 crn;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572426
+
+ char cdb[cdb_size];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572410
+
+ char dataout[];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725797
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572429
+
+ u32 sense_len;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572430
+
+ u32 residual;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572432
+
+ u16 status_qualifier;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572434
+
+ u8 status;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572435
+
+ u8 response;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572437
+
+ u8 sense[sense_size];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572439
+
+ char datain[];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572471
+
+};
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572410
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572476
+
+/* command-specific response values */
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572480
+
+#define VIRTIO_SCSI_S_OK 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572483
+
+#define VIRTIO_SCSI_S_OVERRUN 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572489
+
+#define VIRTIO_SCSI_S_ABORTED 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572491
+
+#define VIRTIO_SCSI_S_BAD_TARGET 3
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572494
+
+#define VIRTIO_SCSI_S_RESET 4
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665324
+
+#define VIRTIO_SCSI_S_BUSY 5
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665325
+
+#define VIRTIO_SCSI_S_TRANSPORT_FAILURE 6
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665326
+
+#define VIRTIO_SCSI_S_TARGET_FAILURE 7
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665326
+
+#define VIRTIO_SCSI_S_NEXUS_FAILURE 8
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665326
+
+#define VIRTIO_SCSI_S_FAILURE 9
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572502
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572507
+
+/* task_attr */
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572510
+
+#define VIRTIO_SCSI_S_SIMPLE 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572513
+
+#define VIRTIO_SCSI_S_ORDERED 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572516
+
+#define VIRTIO_SCSI_S_HEAD 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322572504
+
+#define VIRTIO_SCSI_S_ACA 3
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322725062
+The
+\series bold
+lun
+\series default
+ field addresses a target and logical unit in the virtio-scsi device's SCSI
+ domain.
+ The only supported format for the LUN field is: first byte set to 1, second
+ byte set to target, third and fourth byte representing a single level LUN
+ structure, followed by four zero bytes.
+ With this representation, a virtio-scsi device can serve up to 256 targets
+ and 16384 LUNs per target.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572562
+The
+\series bold
+id
+\series default
+ field is the command identifier (
+\begin_inset Quotes eld
+\end_inset
+
+tag
+\begin_inset Quotes erd
+\end_inset
+
+).
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322725122
+
+\series bold
+task_attr
+\series default
+,
+\series bold
+prio
+\series default
+ and
+\series bold
+crn
+\series default
+ should be left to zero.
+
+\series bold
+task_attr
+\series default
+ defines the task attribute as in the table above, but all task attributes
+ may be mapped to SIMPLE by the device;
+\series bold
+crn
+\series default
+ may also be provided by clients, but is generally expected to be 0.
+ The maximum CRN value defined by the protocol is 255, since CRN is stored
+ in an 8-bit integer.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572647
+All of these fields are defined in SAM.
+ They are always read-only, as are the
+\series bold
+cdb
+\series default
+ and
+\series bold
+dataout
+\series default
+ field.
+ The
+\series bold
+cdb_size
+\series default
+ is taken from the configuration space.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572919
+
+\series bold
+sense
+\series default
+ and subsequent fields are always write-only.
+ The
+\series bold
+sense_len
+\series default
+ field indicates the number of bytes actually written to the sense buffer.
+ The
+\series bold
+residual
+\series default
+ field indicates the residual size, calculated as
+\begin_inset Quotes eld
+\end_inset
+
+data_length - number_of_transferred_bytes
+\begin_inset Quotes erd
+\end_inset
+
+, for read or write operations.
+ For bidirectional commands, the number_of_transferred_bytes includes both
+ read and written bytes.
+ A residual field that is less than the size of datain means that the dataout
+ field was processed entirely.
+ A residual field that exceeds the size of datain means that the dataout
+ field was processed partially and the datain field was not processed at
+ all.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572971
+The
+\series bold
+status
+\series default
+ byte is written by the device to be the status code as defined in SAM.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322572971
+The
+\series bold
+response
+\series default
+ byte is written by the device to be one of the following:
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322572971
+VIRTIO_SCSI_S_OK when the request was completed and the status byte is filled
+ with a SCSI status code (not necessarily "GOOD").
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322572971
+VIRTIO_SCSI_S_OVERRUN if the content of the CDB requires transferring more
+ data than is available in the data buffers.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322652973
+VIRTIO_SCSI_S_ABORTED if the request was cancelled due to an ABORT TASK
+ or ABORT TASK SET task management function.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322573041
+VIRTIO_SCSI_S_BAD_TARGET if the request was never processed because the
+ target indicated by the
+\series bold
+lun
+\series default
+ field does not exist.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322653176
+VIRTIO_SCSI_S_RESET if the request was cancelled due to a bus or device
+ reset (including a task management function).
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322572971
+VIRTIO_SCSI_S_TRANSPORT_FAILURE if the request failed due to a problem in
+ the connection between the host and the target (severed link).
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322572971
+VIRTIO_SCSI_S_TARGET_FAILURE if the target is suffering a failure and the
+ guest should not retry on other paths.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322572971
+VIRTIO_SCSI_S_NEXUS_FAILURE if the nexus is suffering a failure but retrying
+ on other paths might yield a different result.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322664259
+VIRTIO_SCSI_S_BUSY if the request failed but retrying on the same path should
+ work.
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322664258
+VIRTIO_SCSI_S_FAILURE for other host or guest error.
+ In particular, if neither dataout nor datain is empty, and the VIRTIO_SCSI_F_IN
+OUT feature has not been negotiated, the request will be immediately returned
+ with a response equal to VIRTIO_SCSI_S_FAILURE.
+
+\end_layout
+
+\begin_layout Section*
+
+\change_inserted 1531152142 1322573130
+Device Operation: controlq
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322573193
+The controlq is used for other SCSI transport operations.
+ Requests have the following format:
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322573233
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573243
+
+struct virtio_scsi_ctrl {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573246
+
+ u32 type;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573248
+
+ ...
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573250
+
+ u8 response;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574229
+
+};
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574230
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574236
+
+/* response values valid for all commands */
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574310
+
+#define VIRTIO_SCSI_S_OK 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665338
+
+#define VIRTIO_SCSI_S_BAD_TARGET 3
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665342
+
+#define VIRTIO_SCSI_S_BUSY 5
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665355
+
+#define VIRTIO_SCSI_S_TRANSPORT_FAILURE 6
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665357
+
+#define VIRTIO_SCSI_S_TARGET_FAILURE 7
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665358
+
+#define VIRTIO_SCSI_S_NEXUS_FAILURE 8
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665359
+
+#define VIRTIO_SCSI_S_FAILURE 9
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665363
+
+#define VIRTIO_SCSI_S_INCORRECT_LUN 12
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322573193
+The
+\series bold
+type
+\series default
+ identifies the remaining fields.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322573193
+The following commands are defined:
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322576973
+Task
+\begin_inset space \space{}
+\end_inset
+
+management
+\begin_inset space \space{}
+\end_inset
+
+function
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_ABORT_TASK 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_ABORT_TASK_SET 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_CLEAR_ACA 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET 3
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET 4
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET 5
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_QUERY_TASK 6
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_T_TMF_QUERY_TASK_SET 7
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+struct virtio_scsi_ctrl_tmf
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+{
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725821
+
+ // Read-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725810
+
+ u32 type;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+ u32 subtype;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+ u64 id;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725832
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+ u8 response;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+}
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+/* command-specific response values */
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322573683
+
+#define VIRTIO_SCSI_S_FUNCTION_COMPLETE 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665370
+
+#define VIRTIO_SCSI_S_FUNCTION_SUCCEEDED 10
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322665370
+
+#define VIRTIO_SCSI_S_FUNCTION_REJECTED 11
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322725968
+The type is VIRTIO_SCSI_T_TMF; the subtype field defines.
+ All fields except
+\series bold
+response
+\series default
+ are filled by the driver.
+ The
+\series bold
+subtype
+\series default
+ field must always be specified and identifies the requested task management
+ function.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322725982
+Other fields may be irrelevant for the requested TMF; if so, they are ignored
+ but they should still be present.
+ The
+\series bold
+lun
+\series default
+ field is in the same format specified for request queues; the single level
+ LUN is ignored when the task management function addresses a whole I_T
+ nexus.
+ When relevant, the value of the
+\series bold
+id
+\series default
+ field is matched against the id values passed on the requestq.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574270
+The outcome of the task management function is written by the device in
+ the response field.
+ The command-specific response values map 1-to-1 with those defined in SAM.
+\end_layout
+
+\end_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322576979
+Asynchronous
+\begin_inset space \space{}
+\end_inset
+
+notification
+\begin_inset space \space{}
+\end_inset
+
+query
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_T_AN_QUERY 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+struct virtio_scsi_ctrl_an {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725848
+
+ // Read-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725843
+
+ u32 type;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+ u32 event_requested;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725838
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725838
+
+ u32 event_actual;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+ u8 response;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+}
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_OPERATIONAL_CHANGE 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_POWER_MGMT 4
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_EXTERNAL_REQUEST 8
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_MEDIA_CHANGE 16
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_MULTI_HOST 32
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574160
+
+#define VIRTIO_SCSI_EVT_ASYNC_DEVICE_BUSY 64
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574687
+By sending this command, the driver asks the device which events the given
+ LUN can report, as described in paragraphs 6.6 and A.6 of the SCSI MMC specificat
+ion.
+ The driver writes the events it is interested in into the event_requested;
+ the device responds by writing the events that it supports into event_actual.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574688
+The
+\series bold
+type
+\series default
+ is VIRTIO_SCSI_T_AN_QUERY.
+ The
+\series bold
+lun
+\series default
+ and
+\series bold
+event_requested
+\series default
+ fields are written by the driver.
+ The
+\series bold
+event_actual
+\series default
+ and
+\series bold
+response
+\series default
+ fields are written by the device.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574345
+No command-specific values are defined for the response byte.
+\end_layout
+
+\end_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322576981
+Asynchronous
+\begin_inset space \space{}
+\end_inset
+
+notification
+\begin_inset space \space{}
+\end_inset
+
+subscription
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574354
+
+#define VIRTIO_SCSI_T_AN_SUBSCRIBE 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+struct virtio_scsi_ctrl_an {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725858
+
+ // Read-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+ u32 type;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+ u32 event_requested;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725864
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+ u32 event_actual;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+ u8 response;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574342
+
+}
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574708
+By sending this command, the driver asks the specified LUN to report events
+ for its physical interface, again as described in the SCSI MMC specification.
+ The driver writes the events it is interested in into the event_requested;
+ the device responds by writing the events that it supports into event_actual.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574709
+Event types are the same as for the asynchronous notification query message.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574710
+The
+\series bold
+type
+\series default
+ is VIRTIO_SCSI_T_AN_SUBSCRIBE.
+ The
+\series bold
+lun
+\series default
+ and
+\series bold
+event_requested
+\series default
+ fields are written by the driver.
+ The
+\series bold
+event_actual
+\series default
+ and
+\series bold
+response
+\series default
+ fields are written by the device.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574419
+No command-specific values are defined for the response byte.
+\end_layout
+
+\end_deeper
+\begin_layout Section*
+
+\change_inserted 1531152142 1322574433
+Device Operation: eventq
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322653610
+The eventq is used by the device to report information on logical units
+ that are attached to it.
+ The driver should always leave a few buffers ready in the eventq.
+ In general, the device will not queue events to cope with an empty eventq,
+ and will end up dropping events if it finds no buffer ready.
+ However, when reporting events for many LUNs (e.g.
+ when a whole target disappears), the device can throttle events to avoid
+ dropping them.
+ For this reason, placing 10-15 buffers on the event queue should be enough.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574442
+Buffers are placed in the eventq and filled by the device when interesting
+ events occur.
+ The buffers should be strictly write-only (device-filled) and the size
+ of the buffers should be at least the value given in the device's configuration
+ information.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574487
+Buffers returned by the device on the eventq will be referred to as "events"
+ in the rest of this section.
+ Events have the following format:
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574508
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+#define VIRTIO_SCSI_T_EVENTS_MISSED 0x80000000
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+struct virtio_scsi_event {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725871
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+ u32 event;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+ ...
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574500
+
+}
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574516
+If bit 31 is set in the event field, the device failed to report an event
+ due to missing buffers.
+ In this case, the driver should poll the logical units for unit attention
+ conditions, and/or do whatever form of bus scan is appropriate for the
+ guest operating system.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574521
+Other data that the device writes to the buffer depends on the contents
+ of the event field.
+ The following events are defined:
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1322653652
+No
+\begin_inset space \space{}
+\end_inset
+
+event
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574545
+
+#define VIRTIO_SCSI_T_NO_EVENT 0
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322576984
+This event is fired in the following cases:
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322574588
+When the device detects in the eventq a buffer that is shorter than what
+ is indicated in the configuration field, it might use it immediately and
+ put this dummy value in the event field.
+ A well-written driver will never observe this situation.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322574604
+When events are dropped, the device may signal this event as soon as the
+ drivers makes a buffer available, in order to request action from the driver.
+ In this case, of course, this event will be reported with the VIRTIO_SCSI_T_EVE
+NTS_MISSED flag.
+
+\end_layout
+
+\end_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322576985
+Transport
+\begin_inset space \space{}
+\end_inset
+
+reset
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+#define VIRTIO_SCSI_T_TRANSPORT_RESET 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725908
+
+struct virtio_scsi_event_reset {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725876
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+ u32 event;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+ u32 reason;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+}
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+#define VIRTIO_SCSI_EVT_RESET_HARD 0
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+#define VIRTIO_SCSI_EVT_RESET_RESCAN 1
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322574628
+
+#define VIRTIO_SCSI_EVT_RESET_REMOVED 2
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322574756
+By sending this event, the device signals that a logical unit on a target
+ has been reset, including the case of a new device appearing or disappearing
+ on the bus.The device fills in all fields.
+ The
+\series bold
+event
+\series default
+ field is set to VIRTIO_SCSI_T_TRANSPORT_RESET.
+ The
+\series bold
+lun
+\series default
+ field addresses a logical unit in the SCSI host.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322577082
+The
+\series bold
+reason
+\series default
+ value is one of the three #define values appearing above:
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577449
+
+\series bold
+VIRTIO_SCSI_EVT_RESET_REMOVED
+\series default
+ (
+\begin_inset Quotes eld
+\end_inset
+
+LUN/target removed
+\begin_inset Quotes erd
+\end_inset
+
+) is used if the target or logical unit is no longer able to receive commands.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577452
+
+\series bold
+VIRTIO_SCSI_EVT_RESET_HARD
+\series default
+ (
+\begin_inset Quotes eld
+\end_inset
+
+LUN hard reset
+\begin_inset Quotes erd
+\end_inset
+
+) is used if the logical unit has been reset, but is still present.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577446
+
+\series bold
+VIRTIO_SCSI_EVT_RESET_RESCAN
+\series default
+ (
+\begin_inset Quotes eld
+\end_inset
+
+rescan LUN/target
+\begin_inset Quotes erd
+\end_inset
+
+) is used if a target or logical unit has just appeared on the device.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1328439419
+The
+\begin_inset Quotes eld
+\end_inset
+
+removed
+\begin_inset Quotes erd
+\end_inset
+
+ and
+\begin_inset Quotes eld
+\end_inset
+
+rescan
+\begin_inset Quotes erd
+\end_inset
+
+ events, when sent for LUN 0, may apply to the entire target.
+ After receiving them the driver should ask the initiator to rescan the
+ target, in order to detect the case when an entire target has appeared
+ or disappeared.
+ These two events will never be reported unless the
+\series bold
+VIRTIO_SCSI_F_HOTPLUG
+\series default
+ feature was negotiated between the host and the guest.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322577057
+Events will also be reported via sense codes (this obviously does not apply
+ to newly appeared buses or targets, since the application has never discovered
+ them):
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577457
+\begin_inset Quotes eld
+\end_inset
+
+LUN/target removed
+\begin_inset Quotes erd
+\end_inset
+
+ maps to sense key ILLEGAL REQUEST, asc 0x25, ascq 0x00 (LOGICAL UNIT NOT
+ SUPPORTED)
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577460
+\begin_inset Quotes eld
+\end_inset
+
+LUN hard reset
+\begin_inset Quotes erd
+\end_inset
+
+ maps to sense key UNIT ATTENTION, asc 0x29 (POWER ON, RESET OR BUS DEVICE
+ RESET OCCURRED)
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1322577462
+\begin_inset Quotes eld
+\end_inset
+
+rescan LUN/target
+\begin_inset Quotes erd
+\end_inset
+
+ maps to sense key UNIT ATTENTION, asc 0x3f, ascq 0x0e (REPORTED LUNS DATA
+ HAS CHANGED)
+\change_unchanged
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322575482
+The preferred way to detect transport reset is always to use events, because
+ sense codes are only seen by the driver when it sends a SCSI command to
+ the logical unit or target.
+ However, in case events are dropped, the initiator will still be able to
+ synchronize with the actual state of the controller if the driver asks
+ the initiator to rescan of the SCSI bus.
+ During the rescan, the initiator will be able to observe the above sense
+ codes, and it will process them as if it the driver had received the equivalent
+ event.
+
+\end_layout
+
+\end_deeper
+\begin_layout Description
+
+\change_inserted 1531152142 1322576987
+Asynchronous
+\begin_inset space \space{}
+\end_inset
+
+notification
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset listings
+inline false
+status open
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+#define VIRTIO_SCSI_T_ASYNC_NOTIFY 2
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725913
+
+struct virtio_scsi_event_an {
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322725880
+
+ // Write-only part
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+ u32 event;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+ u8 lun[8];
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+ u32 reason;
+\end_layout
+
+\begin_layout Plain Layout
+
+\change_inserted 1531152142 1322575505
+
+}
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_deeper
+\begin_layout Standard
+
+\change_inserted 1531152142 1322575520
+By sending this event, the device signals that an asynchronous event was
+ fired from a physical interface.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322575546
+All fields are written by the device.
+ The
+\series bold
+event
+\series default
+ field is set to VIRTIO_SCSI_T_ASYNC_NOTIFY.
+ The
+\series bold
+lun
+\series default
+ field addresses a logical unit in the SCSI host.
+ The
+\series bold
+reason
+\series default
+ field is a subset of the events that the driver has subscribed to via the
+ "Asynchronous notification subscription" command.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1322575520
+When dropped events are reported, the driver should poll for asynchronous
+ events manually using SCSI commands.
+\change_unchanged
+
+\end_layout
+
+\end_deeper
+\begin_layout Chapter*
Appendix X: virtio-mmio
\end_layout
--
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