On 9/28/2010 8:18 AM, Arnd Bergmann wrote:

On Tuesday 28 September 2010, Michael S. Tsirkin wrote:

quoted

On Tue, Sep 28, 2010 at 04:39:59PM +0200, Arnd Bergmann wrote:

quoted

Can you be more specific what the problem is? Do you think
it breaks when a guest sends VLAN tagged frames or when macvtap
is connected to a VLAN interface that adds another tag (or
only the combination)?

I expect the protocol value to be wrong when guest sends vlan tagged
frames as 802.1q frames have a different format.

Ok, I see. Would that be fixed by using eth_type_trans()? I don't
see any code in there that tries to deal with the VLAN tag, so
do we have the same problem in the tun/tap driver?

tun_get_user() does call eth_type_trans(). Not sure why i didn't use it 
in macvtap code.
Need to test it with guest VLAN tagging to make sure it works.

Also, I wonder how we handle the case where both the guest and
the host do VLAN tagging. Does the host transparently override
the guest tag, or does it add a nested tag? More importantly,
what should it do?
	

I would think If both guest and host do VLAN tagging, the tags will be 
nested.

Thanks
Sridhar