Re: [PATCH] enable ethtool for xen loopback interface(network in dom0)

[Greg Brackley <lists-xen-devel@lucidsolutions.co.nz>]

----- Original Message ----- 
From: "Jan Niehusmann" <jan@gondor.com>
> this patch allows disabling the tx checksums on the xen loopback
> interface, which is used for the virtual interfaces of dom0 instead
> of netfront/netback.

Great patch thanks. I finally got around to upgrading a box to Xen 3.0 
testing (changeset 8269:a91e4dcf629d), applied the patch and it works a 
dream.  I can now bridge the xen0 domain onto a VLAN interface with a 
pro/1000 MT server NIC (82546EB).

I am using Fedora Core 4 (which doesn't appear to support -K ethtool options 
in the initscripts), and have added a /sbin/ifup-local script [1] to the 
system. This in conjunction with adding 'ETHTOOL_KOPTS="tx off"' [2] to my 
interface configuration works well (Note: I use the standard initscripts to 
bring up the networking, and not 'network-bridge').

I'm concerned that there may be some performance hit with software 
checksumming, but I'm happy with working rather than faster. Getting jumbo 
frame support in the domU's would be probably be a better performance boost.

Greg :-)

--
[1] /sbin/ifup-local
#!/bin/sh

cd /etc/sysconfig/network-scripts
. network-functions

[ -f ../network ] && . ../network

CONFIG="ifcfg-${1}"
source_config

if [ -n "$ETHTOOL_KOPTS" ] ; then
        REALDEVICE=${DEVICE%%:*}
        /sbin/ethtool -K ${REALDEVICE} $ETHTOOL_KOPTS
fi


[2]  /etc/sysconfig/network-scripts/ifcfg-veth0
DEVICE=veth0
TYPE=Ethernet
ONBOOT=yes
IPADDR=192.168.133.1
NETMASK=255.255.255.0
MACADDR=00:aa:00:00:85:01
NOZEROCONF=yes
GATEWAY=192.168.133.254
ARP=yes
ETHTOOL_KOPTS="tx off"