Re: [Qemu-devel] How to reserve guest physical region for ACPI

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 4 Jan 2016 21:17:31 +0100
Laszlo Ersek <lersek@redhat.com> wrote:

> Michael CC'd me on the grandparent of the email below. I'll try to add
> my thoughts in a single go, with regard to OVMF.
> 
> On 12/30/15 20:52, Michael S. Tsirkin wrote:
> > On Wed, Dec 30, 2015 at 04:55:54PM +0100, Igor Mammedov wrote:  
> >> On Mon, 28 Dec 2015 14:50:15 +0200
> >> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >>  
> >>> On Mon, Dec 28, 2015 at 10:39:04AM +0800, Xiao Guangrong wrote:  
> >>>>
> >>>> Hi Michael, Paolo,
> >>>>
> >>>> Now it is the time to return to the challenge that how to reserve guest
> >>>> physical region internally used by ACPI.
> >>>>
> >>>> Igor suggested that:
> >>>> | An alternative place to allocate reserve from could be high memory.
> >>>> | For pc we have "reserved-memory-end" which currently makes sure
> >>>> | that hotpluggable memory range isn't used by firmware
> >>>> (https://lists.nongnu.org/archive/html/qemu-devel/2015-11/msg00926.html)  
> 
> OVMF has no support for the "reserved-memory-end" fw_cfg file. The
> reason is that nobody wrote that patch, nor asked for the patch to be
> written. (Not implying that just requesting the patch would be
> sufficient for the patch to be written.)
Hijacking this part of thread to check if OVMF would work with memory-hotplug
and if it needs "reserved-memory-end" support at all.

How OVMF determines which GPA ranges to use for initializing PCI BARs
at boot time, more specifically 64-bit BARs.