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Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack |
Date: |
Wed, 31 Mar 2010 23:03:05 +0300 |
On 3/31/10, Anthony Liguori <address@hidden> wrote:
> On 03/31/2010 02:38 PM, Blue Swirl wrote:
>
> > On 3/31/10, Michael S. Tsirkin<address@hidden> wrote:
> >
> >
> > > On Wed, Mar 31, 2010 at 03:38:05PM -0300, Luiz Capitulino wrote:
> > > > On Wed, 31 Mar 2010 13:26:23 -0500
> > > > Anthony Liguori<address@hidden> wrote:
> > > >
> > > > > On 03/31/2010 01:20 PM, Michael S. Tsirkin wrote:
> > > > > > From: David L Stevens<address@hidden>
> > > > > >
> > > > > > vhost driver in qemu didn't ack features, and this happens
> > > > > > to work because we don't really require any features. However,
> > > > > > it's better not to rely on this. This patch passes features to
> > > > > > vhost as guest acks them.
> > > > > >
> > > > > > Signed-off-by: David L Stevens<address@hidden>
> > > > > > Signed-off-by: Michael S. Tsirkin<address@hidden>
> > > > > > ---
> > > > > >
> > > > > > Anthony, here's a fixup patch to address an issue in vhost
> > > > > > patches. Incidentially, what's the status of the vhost
> patchset?
> > > > > >
> > > > >
> > > > >
> http://repo.or.cz/w/qemu/aliguori-queue.git
> vhost
> > > > >
> > > > > Is what I'm currently testing. With vhost disabled, the
> following seg
> > > > > faults:
> > > > >
> > > > > qemu-system-x86_64 -hda ~/images/linux.img -net tap -net
> > > > > nic,model=virtio -enable-kvm
> > > > >
> > > > > But not when using TCG. I'm not sure that it's your patches at
> fault
> > > > > and I'm attempting to bisect now to figure that out.
> > > >
> > > > Probably this is the same segfault I'm getting right now in master,
> > > > bisect says it's:
> > > >
> > > > """
> > > > commit ad96090a01d848df67d70c5259ed8aa321fa8716
> > > > Author: Blue Swirl<address@hidden>
> > > > Date: Mon Mar 29 19:23:52 2010 +0000
> > > >
> > > > Refactor target specific handling, compile vl.c only once
> > > > """
> > >
> > > Why are the compile once patches helpful? They seem to introduce
> > > churn and bugs, they actively make it harder to extend qemu as you
> can't use
> > > target-specific code in code that is compiled once, they might have
> > > performance penalty - and what do we gain? Any given user is unlikely
> to
> > > need to build on more than one target, distros have enough computing
> > > power to build in parallel.
> > >
> > >
> > As has been explained many times, knowledge about CPU
> specific
> > features has no place in devices. Actively removing CPU specifics from
> > devices is good but preventing new bad code to be committed is better.
> >
> > I don't have distro computing powers (unless some distro's compute
> > center only has two low power machines) and I guess some other
> > developers don't have either. All developers and patch submitters are
> > expected to compile all targets. This patch set has decreased the
> > number of files compiled by about 20%.
> >
> >
>
> BTW, this seems to do it. I'll commit after some testing.
But this makes kvm_enabled() check dynamic and code that was
eliminated by compiler for !CONFIG_KVM will now be generated.
Wouldn't adding CONFIG_KVM to config-host.h also solve the problem?
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, (continued)
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Nathan Froyd, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Blue Swirl, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Aurelien Jarno, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Anthony Liguori, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Anthony Liguori, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Blue Swirl, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack, Anthony Liguori, 2010/03/31
- Re: [Qemu-devel] Re: [PATCH] vhost: fix features ack,
Blue Swirl <=