Re: [Qemu-devel] [PATCH v2] virtio-net: unbreak the minix guest

[Aurelien Jarno]

On Fri, Apr 26, 2013 at 12:49:53PM +0200, Aurelien Jarno wrote:
> On Thu, Apr 25, 2013 at 03:24:23PM +0800, Jason Wang wrote:
> > Multiqueue patchset conditionally add control vq only when guest negotiate 
> > the
> > feature. Though the spec is not clear on this but it breaks the minix guest
> > since it will identify the ctrl vq even if it does not support it. Though 
> > this
> > behavior seems a violation on the spec "If the VIRTIO_NET_F_CTRL_VQ feature 
> > bit
> > is negotiated, identify the control virtqueue.", to keep the backward
> > compatibility, always add the ctrl vq at end of the queues.
> > 
> > Reported-by: Aurelien Jarno <address@hidden>
> > Cc: Aurelien Jarno <address@hidden>
> > Signed-off-by: Jason Wang <address@hidden>
> > 
> > ---
> > Changes from V1:
> > - Drop the unrelated cleanups
> > - Drop the meaningless ctrl parameter of virtio_net_set_multiqueue()
> > ---
> >  hw/net/virtio-net.c |   15 ++++++++-------
> >  1 files changed, 8 insertions(+), 7 deletions(-)
> 
> 
> Thanks a lot for this patch. It fixes the issue observed on Minix. For
> the record it also fixes virtio-net with NetBSD 6.0.1, before it was
> triggering an assertion in QEMU.
> 
> Now that the problem is clear, I will try to work on fixing the problem
> on the OS side when I find some time.
> 

For the record, now that I understand the problem, I have been able to
fix the issue on the guest side. Here are the links to the bug reports
and patches:

- Minix: 
https://gforge.cs.vu.nl/gf/project/minix/tracker/?action=TrackerItemEdit&tracker_item_id=653

- NetBSD: http://gnats.netbsd.org/47780

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net