Re: Checksumming problem in pv_ops dom0 kernel / netback

["Pasi Kärkkäinen" <pasik@iki.fi>]

On Thu, Apr 15, 2010 at 09:20:39AM +0100, Ian Campbell wrote:
> On Tue, 2010-03-30 at 23:58 +0100, Scott Garron wrote:
> > S.H. Verbrugge wrote:
> > > Ever since we switched to a pv_ops dom0 kernel (we were using 2.6.26 
> > > xenkernel from Debian repo before, with Xen 3.2), we started to have 
> > > some problems when attempting to route packets on a domU.
> > 
> >       I'm having the same problem.  All TCP packets that are forwarded
> > through a domU are somehow getting a static checksum (0x9e85) just as
> > they're being put out on the wire.  ICMP is dropped by the dom0, as you
> > describe, with the "Attempting to checksum a non UDP/TCP packet" message
> > in dmesg.  More detail about my situation is in my post to xen-users, here:
> > 
> > http://lists.xensource.com/archives/html/xen-users/2010-03/msg00846.html
> > 
> >       It doesn't include a solution, though.
> > 
> > > This is a tg3 interface
> > 
> >       I'm also running the tg3 ethernet driver, which may be of
> > significance.
> 
> According to the driver source some tg3 chipsets are known to have
> broken checksumming hardware, in particular 5700 B0 silicon. The
> workaround seems to have been present in the driver forever though so
> that may be a red-herring.
> 

Recently there was a fix for a bug in netback.. so you might want to update
to latest pvops dom0 kernel from xen/stable-2.6.32.x branch and see if that
fixes the problem.

-- Pasi