Spec update.

Hi all,
I've gone through the post 0.9.5 git tree for pre-virtio OASIS and merged the equivalent of all my changes for consideration.  I'd like MST and Pawel to do the same: I opened issues for both of you :)  I'm going to chase up non-TC members (they'll need to post to the mailing list to cover IP issues) now.  Many are RH, so they should be able to do that quite easily.  FYI below are the outstanding commits since 0.9.5 which aren't yet in our base spec.  I've invited Cornelia to join the TC, and we'll address whether virtio-ccw gets included later.  Cheers, Rusty.  commit be243ee8e26c10c69e2013fd30246e64271a2da5 Author: Paolo Bonzini <>
Date:
Wed Jul 4 14:51:02 2012 +0930
Current QEMU and Linux drivers can export queue parameters via the
virtio-blk configuration space.  Document this, since the next patch
will have to add another configuration field after these.
Signed-off-by: Paolo Bonzini <>
Signed-off-by: Rusty Russell <>  commit 46430e822f4ed4c15c910864de3b95a710cfd65b Author: Paolo Bonzini <>
Date:
Tue Jul 3 15:16:52 2012 +0200
virtio-blk spec: writeback cache enable improvements
This patch introduces two improvements to writeback cache handling
in the virtio-blk spec.
1) The VIRTIO_BLK_F_FLUSH feature is renamed to VIRTIO_BLK_F_WCE, and
QEMU's behavior is documented explicitly as part of the spec: the host
negotiates the feature only if its cache is writeback.  The obvious dual
requirement is imposed on the guest: it should negotiate the feature
only if it is able to send flushes.  And in order to protect against
data loss, the spec now mandates that the host operates in writethrough
mode if the guest does not negotiate VIRTIO_BLK_F_WCE (this behavior
was already _allowed_ by the spec so far).  This can change with every
reset of course; typically the BIOS will run as writethrough, while the
"main" OS will run in writeback mode.  This is a backwards-compatible
refinement geared towards old or limited guests, so there is no need
for a new feature bit.
2) a second feature is added, VIRTIO_BLK_F_CONFIG_WCE, that provides
the same information in the configuration.  This will enable the driver
to modify the write-cache setting at runtime (via sysfs for Linux, via
MODE SELECT for Windows).
Patches for QEMU and Linux will come soonish.
Signed-off-by: Paolo Bonzini <>
Signed-off-by: Rusty Russell <>  commit 96b9a4d3656db6248b057a9d589fef5d9a3aa7d0 Author: Paolo Bonzini <>
Date:
Wed Jul 4 16:02:36 2012 +0200
virtio-blk spec: document topology fields
This completes the changes from yesterday.
Signed-off-by: Paolo Bonzini <>  commit a6f08364ee605ebcaa2a16e6b294cb328ac18be0 Author: Paolo Bonzini <>
Date:
Mon Jul 16 16:24:36 2012 +0200
virtio-scsi spec: unify event structs
All currently defined event structs have the same fields.  Simplify the
driver by enforcing this also for future structs.
Signed-off-by: Paolo Bonzini <>  commit 00871fd5ab31242d756a2d277dbe33854d6c2d0f Author: Paolo Bonzini <>
Date:
Mon Jul 16 16:24:37 2012 +0200
virtio-scsi spec: add configuration change event
This adds an event for changes to LUN parameters, for example capacity.  These
are reported in virtio-blk via configuration changes, and we want a similar
functionality in virtio-scsi too.
There is no list of supported parameter changes, instead we just refer to
the list of sense codes in the SCSI specification.
This event will usually be serviced in one of three ways: 1) call an OS
service to revalidate the disk, either always or only for some specific
sense codes; 2) somehow pass the sense directly to the upper-level driver;
3) inject a TEST UNIT READY command into the upper-level device, so that
the OS will see the unit attention code and react.  Of course a mix of
the three is also possible, depending on how the driver writer prefers
to have his layering violations served.
Signed-off-by: Paolo Bonzini <>  commit cdbad68fd1ccb8b99b3853836e2b38e0bf74361b Author: Cornelia Huck <>
Date:
Tue Sep 4 17:14:01 2012 +0200
virtio-spec: Add virtio-ccw spec.
Add specifications for the new s390 specific virtio-ccw transport.
Signed-off-by: Cornelia Huck <>
Signed-off-by: Rusty Russell <>  commit e945661b40bcfd29efc35dfa73465bcc960bd20b Author: Cornelia Huck <>
Date:
Tue Sep 11 17:34:35 2012 +0200
virtio-ccw: Add secondary indicators.
Add a ccw to specify the location of indicators for configuration
changes and notice how they are to be used.
Signed-off-by: Cornelia Huck <>  commit 67843fe9745e96c10e148f00ba0aa64397c64f06 Author: Cornelia Huck <>
Date:
Mon Oct 29 14:02:38 2012 +0100
virtio-ccw: Clarifications.
Clarify how indicator location is communicated and that the
feature bits are little-endian.
Signed-off-by: Cornelia Huck <>
Signed-off-by: Rusty Russell <>  commit 67023431c8796bc430ec0a79b15bab57e2e0f1f6 Author: Michael S. Tsirkin <>
Date:
Mon Dec 10 12:40:25 2012 +0200
virtio-spec: virtio network device multiqueue support
Add multiqueue support to virtio network device.
Add a new feature flag VIRTIO_NET_F_MQ for this feature, a new
configuration field max_virtqueue_pairs to detect supported number of
virtqueues as well as a new command VIRTIO_NET_CTRL_MQ to program
packet steering for unidirectional protocols.
Signed-off-by: Michael S. Tsirkin <>
Signed-off-by: Rusty Russell <>  commit a4fcbee2c5198375fab01f30656cdac2133049b4 Author: Michael S. Tsirkin <>
Date:
Sun Sep 9 14:08:37 2012 +0300
virtio-spec: fix thinko in multiport documentation
spec numbers ports port0, port 1 etc, then goes on to say
"ports 2 onwards only if MULTIPORT is set".
An obvious thinko, should be port 1 onwards.
Signed-off-by: Michael S. Tsirkin <>
Acked-by: Amit Shah <>
Signed-off-by: Rusty Russell <>  commit f1a218587d6e472a8a909a87cb9d4eb64629ec6d Author: Alexey Zaytsev <>
Date:
Sat Dec 15 23:32:11 2012 +0200
Document VIRTIO_BLK_T_GET_ID
Signed-off-by: Alexey Zaytsev <>
Reviewed-by: Stefan Hajnoczi <>
Signed-off-by: Rusty Russell <>  commit 3c600996f641614d3720c94dd52155aaaba670fa Author: Amos Kong <>
Date:
Wed Jan 9 15:55:23 2013 +0800
virtio-spec: fix two typos
VIRTIO_NET_F_VTRL_VQ -> VIRTIO_NET_F_CTRL_VQ
VIRTIO_NET_CTRL_MQ is defined to 4 in kernel code
Signed-off-by: Amos Kong <>
Reviewed-by: Stefan Hajnoczi <>
Signed-off-by: Rusty Russell <>  commit f058954d131e3dc73058778ad23b241a235ae8e1 Author: Amos Kong <>
Date:
Fri Jan 18 19:05:41 2013 +0800
virtio-spec: set mac address by a new vq command
Virtio-net driver currently programs MAC address byte by byte,
this means that we have an intermediate step where mac is wrong.
This patch introduced a new control command to set MAC address
in one time, and added a new feature flag VIRTIO_NET_F_MAC_ADDR
for this feature.
"mac" field will be set to read-only when VIRTIO_NET_F_CTRL_MAC_ADDR
is acked.
Signed-off-by: Amos Kong <>
Signed-off-by: Rusty Russell <>  commit 88f37f9ec178b664213b77211fec03687b87958b Author: Pawel Moll <>
Date:
Thu Feb 14 10:54:06 2013 +0000
virtio-spec: Define virtio-mmio registers as LE
To solve the never-ending confusions between hosts and guests
of different endianess, define all virtio-mmio registers as LE.
This change should be safe at this stage, because no known
working mixed-endian system exists so there is virtually no
risk of breaking compatibility.
Signed-off-by: Pawel Moll <>
Signed-off-by: Rusty Russell <>  commit 1de3c32e3687689b73b67622421adb656d80ec5b Author: Michael S. Tsirkin <>
Date:
Thu Mar 7 20:02:21 2013 +0200
virtio-ccw: document GPR4/GPR2 cookie values
virtio-ccw on kvm can use a cookie value passed to guest
to optimize channel/VQ lookups.
Document this.
Signed-off-by: Michael S. Tsirkin <>
Reviewed-by: Cornelia Huck <>
Signed-off-by: Rusty Russell <> (s/s390/ccw/)  commit 721861222802d0ebc48564d727a3684f7b21cadd Author: Dmitry Fleytman <>
Date:
Thu Apr 4 10:55:18 2013 +0300
virtio-spec: dynamic network offloads configuration
Virtio-net driver currently negotiates network offloads
on startup via features mechanism and have no ability to
disable and re-enable offloads later.
This patch introduced a new control command that allows
to configure device network offloads state dynamically.
The patch also introduces a new feature flag
VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.
Signed-off-by: Dmitry Fleytman <>
Signed-off-by: Rusty Russell <>  commit a02d91f8729b4a333d525015d22138a86ce9b644 Author: Rusty Russell <>
Date:
Mon Apr 15 12:27:01 2013 +0930
net: add note that you can defer rx queue init until mq enable.
Signed-off-by: Rusty Russell <>  commit 6833b4aaa799fede8c9ae36412d21aa51d66899f Author: Sasha Levin <>
Date:
Mon Apr 15 01:13:48 2013 -0400
virtio-spec: document virtio-9p
Add basic documentation for virtio-9p. I can expand more on device operation,
but I don't think there's anything significant enough for the spec to be
mentioned there. Please let me know if I'm wrong.
Signed-off-by: Sasha Levin <>
Signed-off-by: Rusty Russell <>  commit 4480830192c0d7680d7516bc2d2138ca9ae2f5fb Author: Pranavkumar Sawargaonkar <>
Date:
Mon May 13 12:21:05 2013 +0930
Documentation: virtio: Add emergency write (emerg_wr) config register in virtio console.
[ Enhanced and applied to Lyx not text version --RR ]
Signed-off-by: Pranavkumar Sawargaonkar <>
Signed-off-by: Anup Patel <>
Signed-off-by: Rusty Russell <>  commit f2e013065ef286e33c7e6d279a880551b43e9680 Author: Michael S. Tsirkin <>
Date:
Mon May 20 15:20:52 2013 +0300
virtio-spec: tweak wording for console control vq
control vq is only used if feature bit is
negotiated - it's not enough that device supports
it. Clarify this in the spec.
Signed-off-by: Michael S. Tsirkin <>
Signed-off-by: Rusty Russell <>  commit c19f2dee4975db51fc189910df7d87011925aa82 Author: Rusty Russell <>
Date:
Mon Jun 3 10:57:07 2013 +0930
virtio-spec: small English/punctuation corrections
1. s/These are devices are/These devices are
2. s/Thefirst/The first
3. s/, Guest should/. Guest should
Signed-off-by: Luiz Capitulino <>
Signed-off-by: Rusty Russell <> (minor mod)