PCI passthrough that works under XenServer 6.5 fails under 6.6 (Dundee) Beta #2

On XenServer 6.5 I use the PCI passthrough feature to pass through the onboard LSI 2308 RAID controller.

This is done by:

• Editing '/boot/extlinux.conf' and adding 'pciback.hide=(02:00.0)' to the boot config.
• Using 'xe vm-param-set other-config:pci=0/0000:02:00.0 uuid=<machine uuid>'

The WS2012 R2 domU then boots - and shows the LSI 2308 RAID controller present in device manager (and can access all the drives) - and works fine.

The same setup (modified for Dundee) fails - i.e.

• Edit '/boot/grub/grub.cfg' and add 'xen-pciback.hide=(02:00.0)' to the boot config.
  (I can tell this works as I see in dmesg "[ 0.266196] pciback 0000:02:00.0: seizing device" and 'xl pci-assignable-list' shows "0000:02:00.0" (which I've double checked - is the LSI 2308 onboard).

• Do the same 'xe vm-param-set other-config:pci=0/0000:02:00.0 uuid=<machine uuid>'

If you boot the domU now - it hangs. You get as far as the blue windows flag - with the circling dots underneath, and it stays there forever. If you force-shutdown the domU - and run an 'xe vm-param-clear' to clear out the PCI assignment - the domU can be booted again.

Add it back - it hangs again. The domU does have XenTools installed (from when it successfully boots).

This kind of prevents us from testing it any further - as we need the passthrough working.

Same hardware / setup works fine under 6.5. I've checked the board has the latest BIOS onboard etc.

This might be pilot error - as there is very little Dundee documentation about passthrough out there - but this setup "appears" to want to work (and very similar with the exception of extlinux.conf vs. grub.cfg) works fine under 6.5

-Karl