Re: [PATCH 2/3] tap: implement vhost_call_cb

[Stefano Brivio <sbrivio@redhat.com>]

On Thu, 3 Apr 2025 12:48:42 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Wed, Apr 02, 2025 at 09:16:22AM +0200, Stefano Brivio wrote:
> [snip]
> > >  static int tap_ns_tun(void *arg)
> > >  {
> > > +	/* TODO we need to check if vhost support VIRTIO_NET_F_MRG_RXBUF and VHOST_NET_F_VIRTIO_NET_HDR actually */
> > > +	static const uint64_t features =
> > > +		(1ULL << VIRTIO_F_VERSION_1) | (1ULL << VIRTIO_NET_F_MRG_RXBUF) | (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
> > >  	struct ifreq ifr = { .ifr_flags = IFF_TAP | IFF_NO_PI };  
> > 
> > I kind of wonder, by the way, if IFF_TUN simplifies things here. It's
> > something we should already add, as an option, see also:
> > https://bugs.passt.top/show_bug.cgi?id=49, but if it makes your life
> > easier for any reason you might consider adding it right away.  
> 
> I agree that supporting IFF_TUN would be a good idea in general.  I
> think trying to do it in the middle of this will be unnecessary
> difficulty though.  There are a bunch of places throughout the code
> that assume we have Ethernet headers, and changing that will require a
> pretty wide ranging rework.

Maybe, yes, hence "if it makes your life easier for any reason". If it
does not, it's of course out of scope here...

-- 
Stefano