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-rw-r--r--virtio-v1.0-wd01-part1-specification.txt27
1 files changed, 16 insertions, 11 deletions
diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt
index bc44492..d92a576 100644
--- a/virtio-v1.0-wd01-part1-specification.txt
+++ b/virtio-v1.0-wd01-part1-specification.txt
@@ -1598,8 +1598,6 @@ device except where noted.
2.4.2.3. Feature bits
--------------------
- VIRTIO_BLK_F_BARRIER (0) Host supports request barriers.
-
VIRTIO_BLK_F_SIZE_MAX (1) Maximum size of any single segment is
in “size_max”.
@@ -1634,6 +1632,8 @@ device except where noted.
2.4.2.3.1 Legacy Interface: Feature bits
--------------------
+ VIRTIO_BLK_F_BARRIER (0) Host supports request barriers.
+
VIRTIO_BLK_F_SCSI (7) Device supports scsi packet commands.
2.4.2.4. Device Initialization
@@ -1668,20 +1668,12 @@ the device (not necessarily in order). Each request is of form:
The type of the request is either a read (VIRTIO_BLK_T_IN), a write
(VIRTIO_BLK_T_OUT), or a flush (VIRTIO_BLK_T_FLUSH or
-VIRTIO_BLK_T_FLUSH_OUT[23]). If the device has VIRTIO_BLK_F_BARRIER
-feature the high bit (VIRTIO_BLK_T_BARRIER) indicates that this
-request acts as a barrier and that all preceeding requests must be
-complete before this one, and all following requests must not be
-started until this is complete. Note that a barrier does not flush
-caches in the underlying backend device in host, and thus does not
-serve as data consistency guarantee. Driver must use FLUSH request to
-flush the host cache.
+VIRTIO_BLK_T_FLUSH_OUT[23]).
#define VIRTIO_BLK_T_IN 0
#define VIRTIO_BLK_T_OUT 1
#define VIRTIO_BLK_T_FLUSH 4
#define VIRTIO_BLK_T_FLUSH_OUT 5
- #define VIRTIO_BLK_T_BARRIER 0x80000000
The ioprio field is a hint about the relative priorities of
requests to the device: higher numbers indicate more important
@@ -1760,6 +1752,19 @@ data_len, sense_len and residual in a single write-only buffer;
and the status field is a separate read-only buffer of size 1
byte, by itself.
+2.4.2.5.1. Legacy Interface: Device Operation
+------------------------
+ #define VIRTIO_BLK_T_BARRIER 0x80000000
+
+If the device has VIRTIO_BLK_F_BARRIER
+feature the high bit (VIRTIO_BLK_T_BARRIER) indicates that this
+request acts as a barrier and that all preceeding requests must be
+complete before this one, and all following requests must not be
+started until this is complete. Note that a barrier does not flush
+caches in the underlying backend device in host, and thus does not
+serve as data consistency guarantee. Driver must use FLUSH request to
+flush the host cache.
+
2.4.3. Console Device
====================