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

[Anthony Liguori]

On 12/08/2010 12:27 PM, Luiz Capitulino wrote:
> On Wed, 08 Dec 2010 12:23:12 -0600
> Anthony Liguori<address@hidden>  wrote:
>
>    
> > On 12/08/2010 12:01 PM, Luiz Capitulino wrote:
> >      
> > > 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.
> > >
> > > Signed-off-by: Ryan Harper<address@hidden>
> > > Signed-off-by: Aurelien Jarno<address@hidden>
> > > ---
> > > NOTE: this patch was applied in the v0.12.x branch, but it seems it got
> > >         lost for master
> > >
> > >        
> > No, it was intentional.  We should fix the segv, this is not a known
> > limitation but rather a bug.
> >      
> A TCG bug, I presume?
>    

Dunno, that's why we shouldn't just paper over it.

Regards,

Anthony Liguori

>    
> > Regards,
> >
> > Anthony Liguori
> >
> >      
> > >    vl.c |    6 ++++++
> > >    1 files changed, 6 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/vl.c b/vl.c
> > > index 2dbb6db..bb9c21c 100644
> > > --- a/vl.c
> > > +++ b/vl.c
> > > @@ -5792,6 +5792,12 @@ int main(int argc, char **argv, char **envp)
> > >                fprintf(stderr, "failed to initialize KVM\n");
> > >                exit(1);
> > >            }
> > > +    } else {
> > > +        /* without kvm enabled, we can only support 4095 MB RAM */
> > > +        if (ram_size>   (4095UL<<   20)) {
> > > +            fprintf(stderr, "qemu: without kvm support at most 4095 MB RAM can be 
> > > simulated\n");
> > > +            exit(1);
> > > +        }
> > >        }
> > >
> > >        if (qemu_init_main_loop()) {
> > >
> > >        
> >      
>