Re: [xen-4.0-testing test] 2045: regressions - FAIL

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2010-08-25 at 19:25 +0100, Ian Jackson wrote:
> 
> 
> test-amd64-i386-pair    12 guest-migrate/src_host/dst_host fail REGR.
> vs. 1993
> 
> It seems that PV migration of a domain from one host to another
> doesn't work properly.  Looking at the logs everything is absolutely
> fine except that the domU isn't responding to arps and pings for at
> least the 20s that the test system waits 20s after migration.

This is with a PVops domU kernel? If so then I'm surprised this is a
regression rather than a never passed. Until very recently a pvops
kernel would not even attempt to send a gratuitous ARP after a
migration, which could lead to 20-30s timeouts like this. (I suppose it
might spuriously pass if a test run got very lucky?)

This was fixed in v2.6.36-rc1 and was backported to stable kernel
v2.6.32.19 and various v2.6.(>32).y as well.

Even with the fix in place the gratuitous ARP behaviour is disabled by
default so you need to enable the net.ipv4.conf.<dev>.arp_notify sysctl
for any device you want to send the notifications. When I was testing I
did this by adding
        net.ipv4.conf.default.arp_notify = 1
to /etc/sysctl.conf and that seemed to do the trick.

(remember that we are testing 2.6.32.18 at the moment until 2.6.32.21 is
out)

Ian.