Re: [Xen-devel] [RFC + Queries] Flow of PCI passthrough in ARM

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 20 Oct 2014, manish jaggi wrote:
> On 8 October 2014 20:21, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> > On Wed, Oct 08, 2014 at 07:17:48PM +0530, manish jaggi wrote:
> >> On 8 October 2014 19:15, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> >> > On Wed, 2014-10-08 at 19:07 +0530, manish jaggi wrote:
> >> >> Thanks for replying. As detailed in this thread, I need to create a
> >> >> hypercall that would send the following information to Xen at the time
> >> >> of PCI attach
> >> >> { sbdf , domU sbdf, domainId }.
> >> >> I am not able to find a way to get the domU sbdf from dom0 at the time
> >> >> of pci-attach.
> >> >
> >> > I think it would need to be done by the pciback driver in the dom0
> >> > kernel, which AFAIK is the thing which consistently knows both physical
> >> > and virtual sbdf for a given assigned device.
> >> >
> >> > Ian.
> >> >
> >> Correct, can you point out which data structure holds the domU sbdf
> >> corresponding to the actual sbdf in pciback.
> >
> > See 'xen_pcibk_export_device' or 'xen_pcibk_publish_pci_root'
> > is that what you are referring to?
> 
> Xen docs also mention about xen-pciback.passthrough=1. If I set this
> in dom0 i see that the device is enumerated as the same sbdf in domU,
> but
> a) it is not shown in lspci
> b) no front-back communication is done for reading devices configuration space
> .
> Is option useful / fully implemented for ARM ?

I don't think this option is very useful. I wouldn't worry about it for
now.

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