Re: Problems with PCI passthrough

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, May 31, 2009 at 12:07:30AM -0400, Brian Marcotte wrote:
> I've been trying to use PCI passthrough to give a domU an ethernet
> card. The ethernet is an Intel 559 which I grabbed for the initial
> testing.
> 
>       fxp0 at pci0 dev 1 function 0: i82559 Ethernet, rev 8
> 
> NetBSD/i386 does this no matter how much ram Xen is told to use:
> 
>       xpci0 at xenbus0 id 0: Xen PCI passthrough Interface
>       pci0 at xpci0 bus 10
>       fxp0 at pci0 dev 1 function 0: i82559 Ethernet, rev 8
>       fxp0: interrupting at irq 18, event channel 8
>       xen_alloc_contig: XENMEM_decrease_reservation failed!
>       fxp0: unable to allocate control data, error = 12

I've seen this too with Xen 3.1.4. I don't understand why Xen would not
accept RAM from a domU when the domU tries to give back some memory.

> 
> NetBSD/amd64 works ONLY if I tell Xen to use only 3 GB of RAM. When
> using all 8 GB in the machine, it still probes correctly, but doesn't
> actually move any packets. The card and switch negotiate speed and
> duplex properly.

Looks like a 64bit issue somewhere. I've never been able to reproduce it
myself (but I don't have a systsem with more than 4GB RAM to play with)

> 
> This is NetBSD-current from May 30 and Xen 3.3.1.
> 
> My questions are:
> 
>       Should this work at all on a large memory machine? I can
>       buy a newer ethernet card if that is the main problem.

It should but there are obvisouly bugs around here.

> 
>       Can this be made to work with NetBSD/i386?

Did you try with less than 4GB RAM for Xen ? 

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--