Re: [Qemu-devel] [PATCH] linux-user: Tell guest about big host page sizes

[Richard Henderson <rth@twiddle.net>]

On 06/05/2014 02:43 AM, Alexander Graf wrote:
> We tell the guest its page size via AUX vectors. The guest process then uses
> this page size as information on which boundaries it can mmap() things.
> 
> However, if the host has a bigger page size granularity than the guest, it can
> not fulfill these mmap() requests - which falls apart when MAP_FIXED is passed
> to mmap.
> 
> So in that case, let the guest know that we're running on a bigger page size
> granularity than the target would require.
> 
> This fixes running qemu-ppc (TARGET_PAGE_SIZE=4k) on a 64k page size ppc64 host
> for me.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  linux-user/elfload.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Woot.  Obviously this won't fix all guests, only those that expect a variable
page size to begin.  But it's certainly a step forward.

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~