Re: [PATCH] net: xen-netback: convert to hw_features

[Ian Campbell <Ian.Campbell@eu.citrix.com>]

On Tue, 2011-04-19 at 14:30 +0100, Michał Mirosław wrote:
> On Tue, Apr 19, 2011 at 02:17:53PM +0100, Ian Campbell wrote:
> > On Tue, 2011-04-19 at 12:56 +0100, Michał Mirosław wrote:
> > > Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> > Thanks for beating me to this! However the prototype for
> > xenvif_fix_features is wrong (needs to take a net_device not a xenvif).
> 
> I'll resend v2 with this fix.
> 
> > I fixed it with the following, I also moved the !can_sg MTU clamping
> > into a set_features hook (like we do with netfront). Am I right that
> > this pattern copes with changes to SG via ethtool etc better? I think
> > it's more future proof in any case.
> 
> This looks wrong. Even if SG is turned on, you might get big skbs which
> are linearized. There is a difference in SG capability and SG offload
> status and as I see it the capability is what you need to test for MTU.

So the existing stuff in drivers/net/xen-netfront.c is wrong too?

> > NB: I'm having some issues with my test hardware at the moment so this
> > is reviewed by eye and compile tested only...
> > 
> > I'm also happy for this to be folded into the original with my
> > "Signed-off-/Acked-by Ian Campbell <ian.campbell@citrix.com>" if that is
> > preferable.
> 
> Thanks.
> 
> Best Regards,
> Michał Mirosław