Re: [Qemu-devel] [PATCH 05/13] acpi: add DMAR scope definition for root IOAPIC

[Peter Xu]

On Sun, Feb 21, 2016 at 05:01:02PM +0100, Jan Kiszka wrote:
> >> We have the same problem over with VT-d and IR.
> >>
> >> I don't think the firmware is not the right place, otherwise there would
> >> be an interface in hw to adjust that parameters. I think we should
> >> simply make sure that the qemu user cannot assign devices to those
> >> addresses as they are reserved for the platform devices (the HPET
> >> requires another ID), or even reserve the hole bus for the platform.
> > 
> > 
> > I understand, but it is the firmware that assign addresses, not QEMU/user.
> 
> Right, buses are chosen by the firmware, but device address are
> (optionally) under user control.
> 
> > We need a way to tell the firmware not to use a certain address range,
> > we can do that
> > with fw_config I suppose.
> 
> The pseudo addresses of IOAPIC and HPET are part of ACPI tables, both on
> AMD and Intel. Firmware can evaluate them easily.

Hi, Jan, Marcel,

Could you give me some hint on how to achieve this using fw_config
(restriction on PCI bus numbers)?  I failed to find it out myself.

Thanks in advance.

-- peterx