XenServer 6.5(SP1) - HVM 're0: watchdog timeout' errors - summary...

[Karl Pielorz]

In the vain hope this'll help others having this issue...

Having looked at this now for some time - and run a lot of tests, the 
current best solution to allow a FreeBSD domU under XenServer 6.5 to act as 
a gateway, or run OpenVPN (or dhcpd etc.) and remain agile - is to switch 
to VirtIO NIC's.

  em1000 (em) causes migrations to fail at the destination end.

  Realtek (re) causes 'watchdog errors' - and if you get rid of the 
watchdog code from the driver, you don't see the errors - but the NIC's 
won't pass traffic after a migrate either.

  PV (xn) have the original problem of not being able to provide routed 
traffic from one FreeBSD domU to other domU guests, don't work with OpenVPN 
(apparent 'packet size issues' from packet collation), and don't work for 
hosting dhcpd.

  virtio (vtnet) Work for routing for other domU's, work for OpenVPN, work 
for dhcpd. The *only* disadvantage [aside from possibly performance] I've 
found is that if you migrate a PV (xn) based FreeBSD domU you suffer around 
2-3 seconds of network disconnect.

With a VirtIO (vtnet) interface this can be as high as 18 seconds of 
network disconnect when you migrate. This means there's more of a chance of 
disrupting sessions that were active either on, or through the DomU. But it 
does work.


So until netfront  is fixed (where we can hopefully go back to the 
undoubtedly more efficient PV 'xn' NIC's) - this is the best workaround for 
us - to use virtio (vtnet).

-Karl