Re: [Qemu-devel] [PATCH] qemu-barrier: Fix compiler version check for future gcc versions

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 03, 2012 at 11:11:02PM +0200, Stefan Weil wrote:
> The current check will give a wrong result for gcc-5.x with x < 4.
> Using QEMU_GNUC_PREREQ is simpler and fixes that issue.
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
> 
> With current gcc versions (gcc-4.x) there is no problem.
> Nevertheless, I suggest to fix this in stable versions, too.
> 
> Regards
> 
> Stefan Weil

ACK for stable tree.

>  qemu-barrier.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/qemu-barrier.h b/qemu-barrier.h
> index 7e11197..16f0942 100644
> --- a/qemu-barrier.h
> +++ b/qemu-barrier.h
> @@ -19,7 +19,7 @@
>   * mfence on 32 bit as well, e.g. if built with -march=pentium-m.
>   * However, on i386, there seem to be known bugs as recently as 4.3.
>   * */
> -#if defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 4
> +#if QEMU_GNUC_PREREQ(4, 4)
>  #define smp_mb() __sync_synchronize()
>  #else
>  #define smp_mb() asm volatile("lock; addl $0,0(%%esp) " ::: "memory")
> -- 
> 1.7.10