Re: [virtio-dev] [PATCH v4 1/6] virtio-vsock vhost device: fixed endiannes issue

[Greg Kurz <gkurz@linux.vnet.ibm.com>]

On Fri, 1 Apr 2016 16:32:10 +0200
Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> wrote:

> > and even if you make vhost_init_is_le() extern, this won't work if the device
> > is in legacy mode, and the host and guest have different endianness.
> >
> > This is because vhost_init_is_le() computes vq->is_le as follows when we
> > have CONFIG_VHOST_CROSS_ENDIAN_LEGACY=y:
> >
> > vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
> >
> > and vq->user_be comes from the VHOST_SET_VRING_ENDIAN ioctl.  
> 
> I was wondering if we can just put  vq->is_le = 1  instead of 
> vhost_init_is_le(), and call it a day. virtio-vsock is a virtio 1.0 
> device, so we are always little endian anyway.
> 

Sure, with a comment maybe to explain why it is different from the other vhost
drivers. Something like:

/* virtio-vsock is a virtio 1.0 only device: we can enforce little-endian
 * here, instead of calling vhost_init_is_le() since we don't care for
 * the transitional case.
 */

And of course, you can simply ignore all my previous remarks on the cross-endian
stuff which belongs to the transitional case.

> cheers
> 
> 
> Claudio
> 
> 

Cheers.

--
Greg