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Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with
From: |
Dustin Kirkland |
Subject: |
Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network |
Date: |
Thu, 29 Oct 2009 09:39:56 -0500 |
On Thu, 2009-10-29 at 20:00 +0800, Scott Tsai wrote:
> Excerpts from Mark McLoughlin's message of Thu Oct 29 17:16:43 +0800 2009:
> > Assuming this is something like the virtio-net in 2.6.26, there was no
> > receivable buffers support so (as Scott points out) it must be that
> > we've read a packet from the tap device which is >1514 bytes (or >1524
> > bytes with IFF_VNET_HDR) but the guest has not supplied buffers which
> > are large enough to take it
>
> > One thing to check is that the tap device is being initialized by
> > qemu-kvm using TUNSETOFFLOAD with either zero or TUN_F_CSUM - i.e. GSO
> > should not be enabled, because the guest cannot handle large GSO packets
>
> > Another possibility is that the MTU on the bridge in the host is too
> > large and that's what's causing the large packets to be sent
>
> Using Dustin's image, I see:
> virtio_net_set_features(features: 0x00000930)
> tap_set_offload(csum: 1, tso4: 1, tso6: 1, ecn: 1)
> being called and get an mtu of 1500 on virbr0 using his birdge.sh script.
>
> virtio_net_receive2 was trying to transfer a 1534 byte packet (1524 'size' +
> 10 'virtio_net_hdr')
> and the guest only had 1524 bytes of space in its input descriptors.
>
> BTW, I can also reproduce this running Dustin's image inside Fedora 11's
> qemu-0.10.6-9.fc11.x86_64.
>
> The patch I posted earlier actually only applies to the 0.10 branch, here's a
> patch that compiles for 0.11:
Hi Scott,
Thanks for this. Testing this, kvm doesn't crash. And the guest has
working network connectivity, until I saturate the network connection
with nc. At that point, the guest loses network connectivity all
together. So the fix is not quite ideal, yet.
:-Dustin
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- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, (continued)
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Anthony Liguori, 2009/10/29
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Mark McLoughlin, 2009/10/29
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Dustin Kirkland, 2009/10/29
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Mark McLoughlin, 2009/10/29
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Dustin Kirkland, 2009/10/29
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Mark McLoughlin, 2009/10/29
- [Qemu-devel] [PATCH] whitelist host virtio networking features [was Re: qemu-kvm-0.11 regression, crashes on older ...], Dustin Kirkland, 2009/10/29
- [Qemu-devel] Re: [PATCH] whitelist host virtio networking features [was Re: qemu-kvm-0.11 regression, crashes on older ...], Dustin Kirkland, 2009/10/30
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network,
Dustin Kirkland <=
- Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Scott Tsai, 2009/10/29
[Qemu-devel] Re: qemu-kvm-0.11 regression, crashes on older guests with virtio network, Michael S. Tsirkin, 2009/10/29
Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network, Dustin Kirkland, 2009/10/29