Re: [Xen-devel] pciback bug "secondary bus reset failed"

[Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>]

Pasi Kärkkäinen wrote:
> On Mon, May 24, 2010 at 04:53:01PM +0100, Alex Zeffertt wrote:
> > Hi,
> >
> > I'm trying to passthrough a PCI network card to a domU guest, but I'm 
> > hitting a bug that prevents the IRQ being unbound from dom0.
> > Here are the steps I am taking:
> >
> >  * configure Xen to pass $pci (0000:06:00.0) through to guest VM
> >  * unbind from current driver in dom0 and rebind to pciback:
> >
> >      echo -n $pci > /sys/bus/pci/devices/$pci/driver/unbind
> >      modprobe pciback
> >      echo -n $pci > /sys/bus/pci/drivers/pciback/new_slot
> >      echo -n $pci > /sys/bus/pci/drivers/pciback/bind
> >
> >  * start guest VM
> >
> > I then get the following on the dom0 console
> >
> >   pciback 0000:06:00.0: secondary bus reset failed for device - all functions \
> >   need to be co-assigned - err: 6
> >   pciback 0000:06:00.0: FLR functionality not supported; attempts to use \
> >   secondary bus reset unsuccessful;
> >   pciback 0000:06:00.0: FLR not performed for device
> Please check this wiki page:
> http://wiki.xensource.com/xenwiki/XenPCIpassthrough
>
> It has a chapter about the "all functions need to be co-assigned" error..
>
> -- Pasi
Hi Pasi,

Thanks for your reply.  I think I understand what is happening now.  My card is 
too old to have the Function Level Reset functionality.  This leaves the 
following options:

 1. Assign all the cards that share the PCI bus (0000:06) to the same guest. 
This enables the FLR functionality to be replaced by the bridge's "Secondary Bus 
Reset" functionality
 - or -

 2. Apply the patch referred to on 
http://wiki.xensource.com/xenwiki/XenPCIpassthrough to bypass the FLR

If I can't do number #1 because some cards are in use by dom0 then I guess #2 is 
the only option.  But does #2 require that dom0 has never accessed the card? 
Also, what if you reboot the domU - does the fact that you can't do an FLR on 
the card mean that there will be unpredictable results the 2nd time domU tries 
to initialise it?
Thanks again,

Alex



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