On Tue, Dec 20, 2011 at 11:59:16AM +0000, Mark Marshall wrote: > According to the bits of the PCI spec that I can find, > the option ROM is copied into RAM which is left read-write > while the initialisation vector is called, and the RAM is > then set to read-only after this time. Does your VGA option > ROM use this feature? Do you know of any other's that do?
Yes - the SeaBIOS vga rom will self modify. I've seen several other option roms that self modify. > (This is in the V2.1 and V3.0 PCI spec's. Also in at least > the V3.0 PCI spec is says that the initialisation code is > run in "big real mode", with 4G segments, do you know of > any code that uses this feature?). Yes - I've seen other option roms that only work when called in big-real mode. SeaBIOS supports this. The SeaBIOS vga option rom doesn't require it though. > PS. > I'm interested in this because I wrote the OGP VGA BIOS > (in 16-bit x86 ASM), a while ago now. A choice made for > two reasons really: 1, I hadn't found SeaBIOS (And didn't > know quite how well you could get gcc to produce 16-bit > code), and 2, I really wanted to write a chunk of 16-bit > assembler (this was a hobby, not work, so I felt I could > make a crazy choice like that and get away with it). > > If I get a free afternoon, I will try to convert that code > to use the SeaBIOS VGA framework. It's interesting to note > that we have both implemented features that are not in the > other's BIOS. Sounds interesting. -Kevin _______________________________________________ SeaBIOS mailing list [email protected] http://www.seabios.org/mailman/listinfo/seabios
