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[Qemu-devel] [PATCH 0/2] virtio-net: fix config size for older guests
From: |
Anthony Liguori |
Subject: |
[Qemu-devel] [PATCH 0/2] virtio-net: fix config size for older guests |
Date: |
Sat, 2 Feb 2013 17:06:21 -0600 |
virtio-net multiqueue added a new field to the config layout. The config
layout is rounded up to the nearest power of 2 and this field caused
field causes the size to go from 8 bytes to 16 bytes.
For reasons unknown, the increase in config size causes the Windows
virtio-net driver to fail. This is probably a bug in the driver but
it exposes a larger bug in QEMU.
While we disable features for compatibility machines, we always use the
latest config size. This presents a slightly different machine model
than what we should be exposing.
This series fixes this specific problem such that -M pc-1.3 should work
again with the Windows drivers. -M pc will still fail.
We need to find a better way to do this but in absence of a nicer approach
this seems likes a good compromise for 1.4. I think we need to choose
something like the MAX() config size required by all of the enabled host
features.
Besides -M pc-1.3, another work around would be:
-global virtio-net-pci.mq=off
This should work after this patch series is applied. We can put this
work around in the release notes as suggested for users of the
virtio-win drivers until they are fixed.
Reported-by: Michael Tokarev <address@hidden>
FYI: only lightly tested on my end but so far, it seems to work.
- [Qemu-devel] [PATCH 0/2] virtio-net: fix config size for older guests,
Anthony Liguori <=