On Wed, 2009-01-14 at 09:01 -0700, Alex Williamson wrote:
> On Wed, 2009-01-14 at 10:15 +0000, Mark McLoughlin wrote:
> > On Tue, 2009-01-13 at 14:23 -0700, Alex Williamson wrote:
> > > +static int virtnet_send_command(struct virtnet_info *vi, u8 class, u8
> > > cmd,
> > > + void *data, unsigned int len)
> > > +{
> > > + struct scatterlist sg[3];
> > > + struct {
> > > + u8 class;
> > > + u8 cmd;
> > > + } ctrl_cmd;
> >
> > I'd like to see this defined in virtio_net_hdr.
>
> As part of struct virtio_net_hdr? I'm not sure what that'd buy us and
> would likely break compatibility. Or do you simply mean defined in
> virtio-net.h?
Yep, sorry, I meant virtio-net.h
> > > + u8 ctrl_status;
> > > + unsigned int tmp;
> > > + int i = 0;
> > > +
> > > + if (!vi->cvq)
> > > + return -EFAULT;
> >
> > BUG_ON() probably makes more sense here.
>
> This is to allow a newer virtio_net guest driver to run on an old qemu.
> That's why I don't generate a fatal error if we don't find the control
> queue. In that case the backend will be running in promiscuous mode and
> I think all of these commands can safely fail. Thanks for the comments.
Yep, but what I mean is that virtio_net_send_command() should never be
called if the host doesn't have send queue support - i.e. force the
calling code to think about what should be done on older hosts.
Cheers,
Mark.
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