Hi Eli,
Dne 07. 11. 19 v 2:02 Eli Duttman napsal(a):
TIA for your responses.
I would suggest to check the original linuxbios project [1] archives as it started around 586 era CPUs. Closest match is perhaps "bifferboard" port [2] I did several years ago. The thing to watch was a problem that gcc wanted to emit to new instructions like "cpuid" or "cmov" you need to compile the coreboot with correct gcc options.
First of all the tricky or maybe not so tricky part is RAM bringup. You need either to use cache as RAM, or somehow quickly init the RAM in assembly startup so you can use C stuff from coreboot. The coreboot (used to) have a romcc compiler which uses general registers only + SSE, but you don't have the SSE in your CPU... Perhaps you will have to have your own bootblock with complete RAM bringup. The RAM init seems to be in the datasheet page 37, but this was always a pain to get right. Maybe on such old system it will be just easy as it was on biffer board. You can check initial biffer board check-in in [3].
Unfortunately I'm very busy so I can't help much, although I like the blast from the past idea.
Thanks, Rudolf
[1] https://review.coreboot.org/cgit/coreboot.git/tree/?h=coreboot-v1 [2] https://blogs.coreboot.org/blog/2012/01/17/bifferboard-porting/ [3] https://review.coreboot.org/cgit/coreboot.git/commit/?id=c9da0157c7b35bb7964...