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.  We could further
refine the search criteria based on srcport but that's probably unnecessary.


Won't this slow down nfs/udp?  I think a srcport check would be good here.

--
error compiling committee.c: too many arguments to function

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