Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode

Dustin Kirkland
2009-09-03T21:48:48Z

On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote:
> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote:
>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back
>> to non-accelerated mode
>>
>> We're seeing segfaults on systems without access to /dev/kvm.  It
>> looks like the global kvm_allowed is being set just a little too late
>> in vl.c.  This patch moves the kvm initialization a bit higher in the
>> vl.c main, just after options processing, and solves the segfaults.
>> We're carrying this patch in Ubuntu 9.10 Alpha.  Please apply
>> upstream, or advise if and why this might not be the optimal solution.
>
> Ah discussion about an alternative fix for this fizzled out recently:
>
>  http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html

Ah, thanks Mark. In that thread, I found Daniel's suggestion the most
reasonable, and user-friendly:

On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote:
> Well, we could go for logic like:
>
> * No arg given => try kvm, try kqemu, try tcg
> * --accelmode arg given => try $arg, and fail if unavailable
>
> then libvirt would simply always supply --accelmode for all VMs,
> while people running qemu manually would get best available

:-Dustin