Re: [Xen-users] bad udp cksum by dns request in domU

["Nicholas Lee" <emptysands@xxxxxxxxx>]

On 04/02/06, Patrick Wolfe <pwolfe@xxxxxxxxxxxxxx> wrote:
> On Fri, 2006-02-03 at 12:51 +0100, Nadja Kick wrote:
> > try: ethtool -K eth0 tx off in domU.
>
> This is also needed in dom0!  I edited /etc/xen/scripts/network-bridge,
> adding this command to the end of the op_start() function:
>
>         add_to_bridge2 ${bridge} ${pdev}
>         do_ifup ${netdev}
> +       # disable ip checksum offloading for veth device
> +       ethtool -K ${netdev} tx off

Maybe this is a better patch, as ethtool is not installed by default.
Although maybe it should for xen installs.

        [ -x /usr/sbin/ethtool ] && /usr/sbin/ethtool -K ${netdev} tx off

I'm wondering if these are virutal devices created by the Xen kernel,
why checksum offloading is not turned off by default for all virtual
veth/vif devices. Both for host0 and all domains. Seems better to have
things work for everyone, and point people at optimisation paths. Than
optimise and better things uncertainly. Especially when there is not
clear (well orgranised) documenation.

I'm noting 
http://wiki.xensource.com/xenwiki/XenFaq#head-4ce9767df34fe1c9cf4f85f7e07cb10110eae9b7,
which should be http://wiki.xensource.com/xenwiki/KnownIssues and also
isn't very instructive.

Also KnownIssues should live on the Wiki homepage with a clear pointer.

--
Nicholas Lee
http://stateless.geek.nz
gpg 8072 4F86 EDCD 4FC1 18EF  5BDD 07B0 9597 6D58 D70C

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