Re: [Qemu-devel] [SeaBIOS] [PATCH] acpi: hide 64-bit PCI hole for Windows XP

[Michael S. Tsirkin]

On Mon, Aug 12, 2013 at 08:37:00AM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> > If we make it a rule that PCI is`setup before ACPI tables
> > are read, then QEMU can do the patching itself when
> > it detects BIOS reading the tables.
> 
> Approach makes sense to me.  The ordering constrain shouldn't be a big
> burden, hardware detection+bringup (including pci setup) is the first
> thing done by the firmware, loading/generating acpi tables is one of the
> last things.  And it avoids the need to communicate the addresses (or
> patch locations) between qemu+firmware.
> 
> What do you want to use this for?  pmbase and xbar are simple, they are
> just a single register read.  pci io windows needs a root bus scan, but
> should be doable too.

Right. We'll need to migrate the offsets for patching since
they are tied to specific AML and this can change.

> > Gerd, Laszlo,others,  does this rule work for alternative firmwares?
> 
> It surely works for coreboot, and I would be very surprised if this
> causes trouble for ovmf.
> 
> cheers,
>   Gerd