Anthony Liguori wrote:
With the latest GSO/csum offload patches, any guest using an unpatched version
of dhclient (any Ubuntu guest, for instance), will no longer be able to get
a DHCP address.
dhclient is actually at fault here. It uses AF_PACKET to receive DHCP responses
but does not check auxdata to see if the packet has a valid csum. This causes
it to throw out the DHCP responses it gets from the virtio interface as there
is not a valid checksum.
Fedora has carried a patch to fix their dhclient (it's needed for Xen too) but
this patch has not made it into a release of dhclient. AFAIK, the patch is in
the dhclient CVS but I cannot confirm since their CVS is not public.
This patch, suggested by Rusty, looks for UDP packets (of a normal MTU) and
explicitly adds a checksum to them if they are missing one.
This allows unpatched dhclients to continue to work without needing to update
the guest kernels.
Since v1, we refined the search criteria to only consider packets originating
from a DHCP server. I also added a comment to note that we should disable this
routine when we introduce zero copy.
Applied, thanks.
--
error compiling committee.c: too many arguments to function
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