On Wed, May 11, 2011 at 10:46 AM, Peter Stuge <pe...@stuge.se> wrote: > Graeme Russ wrote: >> >> Would be interesting to investigate implementing a stub in U-Boot to >> >> initialise and use VGA option ROMs >> > >> > VGA option ROMs call BIOS functions. So, one needs a BIOS >> > implementation (eg, SeaBIOS) or an emulator for them (eg, in >> > coreboot). >> >> How many functions are needed? > > That depends completely on the particular VGA option ROM. > > Having as complete a BIOS environment as can possibly be accomplished > is the only hope to making arbitrary option ROMs work. > > Option ROMs are heavily tied into the BIOS concept. > > >> (surely not all the IDE and keyboard stuff for example) > > I think I've seen some VGA option ROM get stuck waiting for > non-working keyboard BIOS services. > > >> - Could the bare minimum be implemented in a stripped-down modified >> SeaBIOS? > > Not really. > > >> All this because stupid hardware manufacturers refuse to release details >> of how to do even the most basic of functions with their hardware :( > > Welcome to coreboot.
OK, well maybe the coreboot/u-boot scenarion goes like this: 1) coreboot initialises SDRAM and other 'critical' hardware 2) coreboot launches a U-Boot payload 3) If U-Boot does not care about console output then move on and boot the OS 4) If U-Boot has a driver for the video hardware then use it for console output 5) If U-Boot does not have a driver then load SeaBIOS (modified a bit) and the VGA option ROM and use BIOS calls for console output horrid, horrid, horrid Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
