Hi Vadim,
thanks for your mail. I have added the flashrom mailing list in CC: because we should develop a generic way to handle DualBIOS and similar techniques.
On 09.04.2010 08:12, Vadim Girlin wrote:
I'm going to try coreboot on Gigabyte GA-MA770-UD3. It's AMD 770 (RX780 / SB700).
My motherboard supports hardware dual bios - with two chips on it. I'm going to try flashing backup chip and boot from it. It seems to be possible - I've tested it (flashing at least). Chips on this board could be switched by changing bit 0 at undocumented register EF on LDN 7 of IT8720. I can use slightly patched flashrom for accessing any chip I want without any problems. And this is tested many times.
My idea is to use backup chip for debugging - that always keeps my chance to reboot from main bios chip. And removes the need for desoldering etc.
And second problem is that original bios is checking second chip - and trying to recover it by flashing the bios from main chip on reboot? rewriting coreboot. AFAICS this could be solved by including some signatures etc. It seems to be easy to find out. May be someone is working on this?
BTW I can send the patch for flashrom - but I think that with information I mentioned above somebody could make it much better than my ugly hack. I hope the regs should be the same for all latest Gigabyte MBs using IT8720/18
It would be great if you could send that patch. It will help us make a flashrom design decision that works for all boards with multiple flash chips.
By the way, some of us have good contacts at ITE, so we can ask ITE for details about the undocumented registers.
Regards, Carl-Daniel