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[Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assump
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions |
Date: |
Tue, 24 Nov 2009 21:54:58 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Tue, Nov 24, 2009 at 01:50:25PM -0600, Anthony Liguori wrote:
> Michael S. Tsirkin wrote:
>> virtio net currently assumes that the first s/g element it gets is
>> always virtio net header. This is wrong.
>> There should be no assumption on sg boundaries. For example, the guest
>> should be able to put the virtio_net_hdr in the front of the skbuf data
>> if there is room. Get rid of this assumption, properly consume space
>> from iovec, always.
>>
>
> Practically speaking, we ought to advertise a feature bit to let a
> kernel know that we are no longer broken.
>
> Otherwise, there are a ton of old userspaces that will break with new
> guests.
My thinking is, first of all let's fix the bug.
We'll add a feature bit when or if some guest wants to use it.
Maybe this will be 100 years down the road when all old userspace
has died a natural death :)
Makes sense?
> --
> Regards,
>
> Anthony Liguori
- [Qemu-devel] [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Michael S. Tsirkin, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Anthony Liguori, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions,
Michael S. Tsirkin <=
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Anthony Liguori, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Michael S. Tsirkin, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Anthony Liguori, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Michael S. Tsirkin, 2009/11/24
- [Qemu-devel] Re: [PATCH] qemu/virtio-net: remove wrong s/g layout assumptions, Michael S. Tsirkin, 2009/11/30