Re: Deferring IP checksum for xennet(4)/xvif(4)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hi,
thanks for looking at this.

On Tue, Mar 17, 2020 at 10:35:36PM +0100, Jaromír Dole?ek wrote:
> [...]
> There are at least two problems with this:
> 1. If destination interface has no hw offloading, it will anyway send
> the packet without checksum. I think this is actually OK, it's
> responsibility of the admin to only enable the Tx/Rx for xennet if hw
> device is hw offload capable.

I don't think it's OK: most linux distros turns on HW checkums by default.
If you boot from an install media, you may not have the tools to
disable it available (I'm not even sure if you can get a shell from
here). We need to handle this case in bridge.

We have code to compute checksums at the interface driver level in
the Xen PV drivers, maybe this can be generalized and used in
bridge ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--