Hi,
That said, though, I don't see a gain in having the acpi code communicate with the pciinit code. Both sets of code are effectively qemu specific, build_mcfg() is only going to get called on q35, and thus the mmconfig struct will always have hard coded values. Might as well have build_mcfg detect q35 and just put the hard-coded values in directly. Let me know if I've missed something.
/me was thinking about making the 32bit pci window dynamic on q35 too, so the mmconfig base address wouldn't be fixed any more. Didn't do it in the end because the window is larger on q35 anyway (qemu wouldn't map ram above 0xb0000000). So, yes, we can just hard-code stuff.
cheers, Gerd