Re: [Xen-devel] Problem with pv-ops dom0 and pci-stub to hide devices: improper device assignment specified

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 13/10/2009 17:12, "Bruce Edge" <bruce.edge@xxxxxxxxx> wrote:

>> Why use pci-stub? It just hides devices, but does not do anything else?
>> 
> 
> I admit some confusion here. What is the difference between these?
> - pciback/pcifront
> - pci passthorugh
> - pci-stub
> 
> I'll gladly RTFM if somone could refer me to the appropriate link.
> 
> We're running 2.6.31.1 pv-ops dom0, and hvm 2.6.30.1 for the domU.

In this case pci passthrough is done without assistance from dom0 kernel,
except that the pci-stub driver is used to 'steal' the device from dom0
(it's just a dummy driver that binds to the device and prevents it being
taken by any other real driver in dom0). Xen-unstable's xend should know how
to drive pci-stub in recent pv_ops Linux kernels. Pciback has this function
in older kernels, and xend knows how to drive that too. Pcifront doesn't
come into it for you -- that's the domU pci driver for PV guests, but in HVM
guests the PCI access method is as native and emulated in qemu.

 -- Keir





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