Re: RFC: PCI devices passthrough on Arm design proposal

[Julien Grall <julien@xxxxxxx>]

Hi Roger,

On 20/07/2020 09:47, Roger Pau Monné wrote:
> On Fri, Jul 17, 2020 at 05:18:46PM +0100, Julien Grall wrote:
> > > Do you really need to specify the ECAM and MMIO regions there?
> > You need to define those values somewhere :). The layout is only shared
> > between the tools and the hypervisor. I think it would be better if they are
> > defined at the same place as the rest of the layout, so it is easier to
> > rework the layout.
> OK, that's certainly a different approach from what x86 uses, where
> the guest memory layout is not defined in the public headers.
It is mostly a convenience as some addresses are used by both the 
hypervisor and tools. A guest should use the firmware tables (ACPI/DT) 
to detect the MMIO regions.
> On x86 my plan would be to add an hypercall that would set the
> position of the ECAM region in the guest physmap, and that would be
> called by the toolstack during domain construction.
It would be possible to use the same on Arm so the hypervisor doesn't 
use hardcoded values for the ECAM.
Cheers,

--
Julien Grall