The last change I had on xen-3.0-testing.hg was:

changeset:   9612:32b22f5286be
user:        kaf24@firebug.cl.cam.ac.uk
date:        Thu Apr  6 18:34:32 2006 +0100
summary:     Fix another blkback kernel thread I introduced. :-( The 
kernel thread

(ignore the changeset number - I checked some stuff into my own hg
repository)

It looks like I had changeset 9579.

I built it from within a Domain 0 running the Debian unstable amd64 
packages from amd64.debian.net.

$ gcc --version
gcc (GCC) 4.0.3 (Debian 4.0.3-1)

I'll attach my gzipped kernel config.

Anything else that would be useful?  I can also grant you access to the 
machine if that would be of any benefit.

Cheers,

  - Jim


Keir Fraser wrote:
> 
> On 9 Apr 2006, at 21:18, Jim Pick wrote:
> 
>>>> Has anybody else encountered this?  Also, if it's already been fixed 
>>>> somewhere, I'd love to know.  Any Netfilter debugging tips would 
>>>> also be appreciated.
>>>
>>> Turn off tx checksum offload in your domU's using ethtool. We had 
>>> fixed some forms of NAT with our checksum offload, but maybe not for 
>>> your type of setup.
>>
>>
>> That fixed it.  Thanks!
> 
> 
> It would be interesting to know more about your configuration, and also 
> what Xen version you were using. Changeset 9579 fixed some bugs, so if 
> your repository is older than that then you might well see problems.
> 
>  -- Keir
>