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

[Aurelien Jarno <aurelien@aurel32.net>]

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.


> Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
> ---
>  vl.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/vl.c b/vl.c
> index db7a178..a659e98 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -5760,6 +5760,12 @@ 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()) {


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