I've looked at the original BIOS source and the internal versions of the documentation, and here's what I've determined: As near as I can tell, you cannot disable the PCI header for the device at 00:12:4. The original BIOS (written by others on the BIOS team here at AMD in Colorado) virtualized the PCI headers via SMM code, and that header was masked when internal graphics were disabled. Without SMM code, you cannot do the same thing.

Interesting info/notes:

If you disable memory space via the PCI header (PCI header register 04, bit 1 -- clear to zero), you should disable it somewhat.

If the F4 Video Configuration trap bit (F0, Index 42h, bit 1) is set, the system will generate SMIs when trying to access the PCI header registers. This should be clear for a non-SMM system.

I suppose you could special-case the device in your PCI scan/enumeration code, but that is probably more kludgy than you'd like. Could you reduce the device's resource requirements to zero?

-- Steve G.

Steve Goodrich (Steven.Goodrich@amd.com)
Advanced Micro Devices, Inc.
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