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

[Kevin O'Connor]

On Fri, Aug 09, 2013 at 06:49:18PM +0300, Michael S. Tsirkin wrote:
> On Fri, Aug 09, 2013 at 12:13:06AM -0400, Kevin O'Connor wrote:
> > I don't think SeaBIOS should continue to do the above once the tables
> > are moved to QEMU.  QEMU has all the info SeaBIOS has, so it can
> > generate the tables correctly on its own.
> > 
> > In all practical situations, the PCI window should be at least an
> > order of magnatude greater than the sum of the PCI bars in the system.
> > If the bars are actually bigger than the window, then things are going
> > to fail - the best the firmware can do is try to fail gracefully.  I
> > don't think it's worth the complexity to design mixed ownership and
> > advanced interfaces just so we can fail slightly better.
> > 
> > If this is a real worry, QEMU can sum all the PCI bars and warn the
> > user if they don't fit.
> 
> 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.

QEMU can do the patching regardless of the order of initialization.
The PCI bar sizes are static - they have no relationship to the timing
of the BIOS PCI initialization.

-Kevin