Hi Jake,
On 26.03.2008 21:05, Jake Peavy wrote:
New member here so forgive this question if it's ridiculous.
The question is actually one I'm really glad to hear.
Has anyone looked at porting Coreboot onto MIPS architecture? Can it be used as a Yamon replacement?
Nobody has looked into it yet, but we welcome all contributions to Coreboot, especially for non-x86 architectures. Please note, though, that the x86 arch (main support area for Coreboot) traditionally has extremely crappy firmware/BIOS compared to any other architecture. I have to admit that I just started to read up on Yamon and it roughly seems to do what we would achieve with a combination of Coreboot and a payload like OpenFirmware.
Coreboot is designed to make lowlevel init fast and easy with clean and well-structured code, supporting diverse payloads. Target settings (northbridge, southbridge, SuperI/O) are compiled in except for the usual bus probing stuff. A Coreboot MIPS target could do it all differently, though. Unfortunately linux-mip.org is down and I could not find out whether Yamon really tries to support all available hardware with one binary. That would be impossible in the x86 world due to inability to probe certain stuff and due to size constraints.
If you decide to look into Coreboot MIPS support, please don't study coreboot v2. The coreboot v3 architecture is a lot cleaner because we learned a lot with previous generations, the code is nicer and we even have a design document which is reasonably accurate. Of course, if the MIPS angle shows considerable problems with the current Coreboot v3 design, we'd be happy to hear about it to improve the design.
By the way, it would be nice to know how execution starts on MIPS (top or bottom of address space). I have a patch which adds handling for bottom-booting architectures to v3, but so far we have seen no use case.
Regards, Carl-Daniel