I have a problem with a specific BIOS (xw4600) that returns a DRHD with cap and ecap set to all ones, i.e. a broken BIOS, stopping VT-d from working.
I know this is the manufacturer's responsibility, but I'm curious as to where these values are derived from. Obviously some are chipset specific, whilst others (error registers etc) appear to just be available (and probably not fixed) memory locations?
The motherboard is X38 based. I've looked through the X38 Express datasheet and the ICH9 datasheet and cannot find the source of many of the values in the DRHD. Where are they defined, and if you're mad enough, is it possible to set up your own DRHD etc instead of using the BIOS (Obviously the DMAR table links to various RMRR and PCI ranges, but in this case there are a series of RMRR set up. If I assume those are correct it may be possible to fix the broken bits)
The specifications are complex., and I'm probably missing some understanding, but I'm reasonably certain I'm lacking documentation.
Thanks
