If we make it a rule that PCI is`setup before ACPI
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.
Gerd, Laszlo,others, does this rule work for
It surely works for coreboot, and I would be very surprised if this
causes trouble for ovmf.