Re: [PATCH 22/25] xen: xen-netfront: use skb.cb for storing private data

Jeremy Fitzhardinge
2007-04-27T22:20:48Z

Herbert Xu wrote:
> Sure thing. I'll look over it soon.
>
> Actually there is one thing I'd like to see changed first up: I noticed
> that you've stripped out the checksum hack which is in the main Xen tree.
> We actually have the code in net-2.6.22 (which is also in mm) that lets
> you use CHECKSUM_PARTIAL on received packets without having to do that
> hack.
>
> Here's the patch that I've been testing so far. It's against the Xen
> source, but should be easy to adapt to your version as well.
>
> I just thought about this again, and in fact we need this change for
> correctness as well as performance. Because not setting ip_summed
> to CHECKSUM_PARTIAL in netfront is not going to stop netback from
> sending CHECKSUM_PARTIAL packets to us. If these packets are then
> routed/bridged back to netback, they'll have the wrong checksum.
>

OK, I've been sitting on this in the hope that I'll suddenly see the
light and work out what you're talking about - but apparently that's not
going to happen. So, some questions:

1. Does this patch change the dom0 <-> domU interface? or does it
fix something that's currently broken?
2. Can just apply the netfront part to the pv_ops kernel, or does it
require the corresponding dom0 patch to be applied as well?

Thanks,
J