Bug in PCI Passthrough

[Josef Vogt <josef.vogt@li-life.li>]

Hello all

I tried to enable PCI Passthrough in my Debian Squeeze installation. 
Unfortunately, it didnt work. The following bug showed up (excerpt from 
dmesg):

[ 10.148612] uhci_hcd 0000:00:14.2: PCI INT D -> Link[LNKD] -> GSI 11
(level, low) -> IRQ 11
[ 4.678352] Failed to setup GSI :11, err_code:-22
[ 4.678480] dmfe 0000:00:0e.0: PCI INT A -> Link[LNKB] -> GSI 11 (level,
low) -> IRQ 11
[ 6.868419] Failed to setup GSI :10, err_code:-22

Strange thing is, it worked perfectly with Debian Lenny Kernel 2.6.26 [1]

I first thought, it was a Debian bug[2], but then I tried the vanilla 
kernel (xen/stable-2.6.32.x from kernel.org) the bug was exactly the 
same. See also [1] for the the exact error messages.
I also tried to get help from xen users list [3].
Strange side note: It seems to work with opensuse 11.2 (kernel 3.6.31) 
and also Opensuse 11.3 (kernel 3.6.34) – I installed them both but didnt 
get the above error message. The interrupts were assigned correctly. So 
i started looking at the code, but the used code in Opensuse looks quite 
different to the xen code in kernel.org. (I didn't find xen.c, where the 
error message „Failed to setup GSI“ is located). Is it possible that 
Opensuse uses Xen source code from an older branch?
I also compiled xen/next-2.6.39 (up to this commit: 
6f3ba85fbef08ce0d833a1943827454b3e5532b7) but then, unfortunately the 
dom0 crashes.

All the above together (except the dom0 crash in 2.6.39, of course) 
let's me think, this could a bug in xen kernel source code.
Greetings!
Josef

[1] 
http://lists.xensource.com/archives/html/xen-users/2011-01/msg00411.html
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=610832
[3] 
http://lists.xensource.com/archives/html/xen-users/2011-01/msg00388.html