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Re: [Qemu-devel] Re: [PATCH-RFC 13/13] virtio-net: connect to vhost net
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] Re: [PATCH-RFC 13/13] virtio-net: connect to vhost net backend |
Date: |
Wed, 24 Feb 2010 07:29:25 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Wed, Feb 24, 2010 at 03:14:25AM +0000, Paul Brook wrote:
> > vnet_hdr is IMHO a really bad example to copy from.
> >
> > vnet_hdr leaks into the migration state via n->has_vnet_hdr. What this
> > means is that if you want to migrate from -net tap -net nic,model=virtio
> > to -net user -net nic,model=virtio, it will fail.
> >
> > This is a hard problem to solve in qemu though because it would require
> > that we implement software GSO which so far, no one has stepped up to do.
>
> Or make virtio-net pass this on to the guest, and have that deal with the
> problem.
This is exacly what we do, via feature bits.
> If you implement software GSO, then devices can assume it's always
> present and don't need to probe.
>
> Paul
Re: [Qemu-devel] Re: [PATCH-RFC 13/13] virtio-net: connect to vhost net backend, Anthony Liguori, 2010/02/24