The issue is to extract useful information (semi-automatically) and create new ATOMBIOS tables (since drivers rely on them, to my knowledge) that are independent enough so we can ship them under own (C).
Best would be to ask AMD to include ATOMbios tables in vendorcode.
Does it sound unreal?
If we get the tables rest is easier, but I also looked into this some time ago and just running ATOMbios interpreter is definetly NOT enough to get some legacy VGA mode. I tried to get in touch with Xorg people and they thought i will need some "driver" for this.
Also please note that the option ROM is more or less just interpreter of the bytecode too.
Thanks Rudolf
Patrick