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Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device |
Date: |
Sat, 8 Dec 2007 14:09:06 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Paul Brook wrote:
> > virtio makes things a bit trickier though. There's a shared ring queue
> > between the host and guest. The ring queue is lock-less and depends on
> > the ability to atomically increment ring queue indices to be SMP safe.
> > Using a copy-API wouldn't be a problem for QEMU since the host and guest
> > are always running in lock-step. A copy API is actually needed to deal
> > with differing host/guest alignment and endianness.
>
> That seems a rather poor design choice, as many architectures don't have an
> atomic increment instruction. Oh well.
Most have compare-and-swap or load-locked/store-conditional
instructions, though, which can be used to implement atomic increment.
-- Jamie
- [Qemu-devel] [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/04
- Re: [Qemu-devel] [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/04
- [Qemu-devel] Re: [PATCH 2/3] virtio network device, Dor Laor, 2007/12/04
- [Qemu-devel] Re: [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/05
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Paul Brook, 2007/12/05
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/05
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Jamie Lokier, 2007/12/06
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Paul Brook, 2007/12/08
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device,
Jamie Lokier <=
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Paul Brook, 2007/12/08
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Blue Swirl, 2007/12/08
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Jamie Lokier, 2007/12/08
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/08
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Rusty Russell, 2007/12/11
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/11
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Rusty Russell, 2007/12/17
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio network device, Anthony Liguori, 2007/12/08