On Tue, May 08, 2007 at 11:39:14AM -0500, Mike McGrath wrote: > We're using xen heavily in Fedora's Infrastructure and presently a > number of the xen domU hosts are experiencing terrible checksum issues. > I've tried the ethtool -K eth0 tx off fix and it didn't work. What sort of network config have you got with these ? Briding straight to physical device, or NAT'd ? > dom0: 2.6.19-1.2911.fc6xen x86_64 > domU: 2.6.20-1.2933.fc6xen x86_64 > > Anyone have any ideas? There are a couple issues at play: - There is a general bug in 2.6.20 that breaks checksum offload when used with NAT. - In 2.6.19 or later Dom0 will transmits to guests using checksum offload, so DHCP client in the guest will mistakenly thing it has a corrupt checksum. To address the first bug requires disabling checksum offload in the eth0 in the guest. ethtool -K eth0 tx off in the guest should do it. To address the 2nd is really difficult since the FC6 install images themsves have a broken DHCP client for example, so we need to workaround it in the kernel. This can be done by disabling checksums on the device in Dom0 - any of vifN.0, xenbr0, phet0 should have ethtook -K <dev> tx off done. NB, ignore eth0 in Dom0, that's a fake device so turning off tx on that does not fix things. So in summary, to get it working in general case requires: ethtool -K eth0 tx off in guest And ethtool -K <dev> tx off on whatever bridge device the guest is attached to We have just fixed both these issues in the latest rawhide kernel available in Koji http://koji.fedoraproject.org/packages/kernel-xen-2.6/2.6.20/2925.7.fc7/ and intend to also apply them to FC5 & 6 asap. Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=| -- Fedora-xen mailing list Fedora-xen@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-xen
