Re: [Qemu-devel] [PATCH] net: don't set native endianness

[Jason Wang <jasowang@redhat.com>]

On 10/14/2015 05:26 PM, Michael S. Tsirkin wrote:
> commit 5be7d9f1b1452613b95c6ba70b8d7ad3d0797991
>     vhost-net: tell tap backend about the vnet endianness
> makes vhost net always try to set LE - even if that matches the
> native endian-ness.
>
> This makes it fail on older kernels on x86 without TUNSETVNETLE support.
>
> To fix, make qemu_set_vnet_le/qemu_set_vnet_be skip the
> ioctl if it matches the host endian-ness.
>
> Reported-by: Marcel Apfelbaum <marcel@redhat.com>
> Cc: Greg Kurz <gkurz@linux.vnet.ibm.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  net/net.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/net/net.c b/net/net.c
> index 28a5597..8e96011 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -517,20 +517,28 @@ void qemu_set_vnet_hdr_len(NetClientState *nc, int len)
>  
>  int qemu_set_vnet_le(NetClientState *nc, bool is_le)
>  {
> +#ifdef HOST_WORDS_BIGENDIAN
>      if (!nc || !nc->info->set_vnet_le) {
>          return -ENOSYS;
>      }
>  
>      return nc->info->set_vnet_le(nc, is_le);
> +#else
> +    return 0;
> +#endif
>  }
>  
>  int qemu_set_vnet_be(NetClientState *nc, bool is_be)
>  {
> +#ifdef HOST_WORDS_BIGENDIAN
> +    return 0;
> +#else
>      if (!nc || !nc->info->set_vnet_be) {
>          return -ENOSYS;
>      }
>  
>      return nc->info->set_vnet_be(nc, is_be);
> +#endif
>  }
>  
>  int qemu_can_send_packet(NetClientState *sender)