Re: [Qemu-devel] [PATCH] Fix segfault with ram_size > 4095M without kvm

[Aurelien Jarno <aurelien@aurel32.net>]

On Tue, Feb 23, 2010 at 03:07:20PM -0600, Anthony Liguori wrote:
> On 02/23/2010 02:30 PM, Alexander Graf wrote:
> >On 23.02.2010, at 18:02, Aurelien Jarno wrote:
> >
> >>Ryan Harper a écrit :
> >>>Currently, x86_64-softmmu qemu segfaults when trying to use>  4095M memsize.
> >>>This patch adds a simple check and error message (much like the 2047 limit on
> >>>32-bit hosts) on ram_size in the control path after we determine we're
> >>>not using kvm
> >>>
> >>>Upstream qemu-kvm is affected if using the -no-kvm option; this patch address
> >>>the segfault there as well.
> >>It looks like workarounding the real bug. At some point both
> >>i386-softmmu (via PAE) and x86_64-softmmu were able to support>  4GB of
> >>memory. I remember adding the support long time ago, and testing it with
> >>32GB of emulated RAM.
> >Sounds like a perfect candidate for -stable then. For HEAD I agree that finding the cause would be the way to go.
> 
> No, it's wrong.  A good candidate for -stable would be something
> that fixes the SEGV :-)
> 

It actually depends on the patch and how invasive it is.

I'll bisect that later this week. For now what I can say it hasn't
worked for a lot of time. It works in 0.9.1, but not in 0.10.0. It
probably hasn't been noticed due to kqemu which was limiting the 
size to 2GB.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net