Re: [Qemu-devel] [PATCH v2 5/5] virtio: optimize virtio_access_is_big_endian() for little-endian targets

[Cornelia Huck]

On Mon, 11 Jan 2016 17:18:06 +0100
Greg Kurz <address@hidden> wrote:

> When adding cross-endian support, we introduced the TARGET_IS_BIENDIAN macro
> and the virtio_access_is_big_endian() helper to have a branchless fast path
> in the virtio memory accessors for targets that don't switch endian.
> 
> This was considered as a strong requirement at the time.
> 
> Now we have added a runtime check for virtio 1.0, which ruins the benefit
> of the virtio_access_is_big_endian() helper for always little-endian targets.
> 
> With this patch, always little-endian targets stop checking for virtio 1.0,
> since the result is little-endian in all cases.
> 
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> v2:
> - simplified the logic as suggested by Laurent Vivier
> ---
>  include/hw/virtio/virtio-access.h |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Cornelia Huck <address@hidden>