Re: Problems with PCI passthrough

[Thor Lancelot Simon <tls%rek.tjls.com@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
> 
> 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.

I have had terrible trouble with PCI passthrough with 32-bit DomU.

I have been able to get it working pretty reliably using 64-bit Dom0
and 32-bit DomU.

The system I'm testing this on has only 2GB RAM, however.  But with 64-bit
DomU I was seeing what looked like symptoms of packets going astray and
clobbering random memory -- and other symptoms that looked like yours, e.g.
mii operations work but actual data transfer often doesn't.

Thor