[coreboot] Hosed ms-7032, I foolishly flashed the bios with a .700

[Carl-Daniel Hailfinger]

Hi Phil,

On 11.06.2009 14:08, Phil Neary wrote:
> I used Flashrom as the utility and am quite comfortable using Linux and the command line.

Good.


> [..] my friends PC, it has the Flashrom utility and my backup.bin. It also has the same type of bios chip (PLCC), And its socketed!
>   

Even better.


> My bios chip is a PLCC (not socketed unfortunately) and the info on the chip is;
>
> Winbond W39V040AP
>   

Ah, the Winbond W39 series. I reread the data sheets dozens of times and
I never found out why these chips sometimes commit suicide during
flashing. It works for some mainboards and fails horribly for others.


> I've thought about unsoldering the chip but don't really have the proper tools.
>   

Some people on this list have experience with desoldering chips. Maybe
they can assist.


> My thought was to purchase another chip and 'kind of' place it on top of the other chip, but I'm not sure how this would go?

Yes, this would work with a bit of soldering. I looked through the data
sheets and came up with a way to do this:
Desolder the ID2 pin of the old chip from the board and connect it to
VDD (3.3V). Solder the new chip (with the correct BIOS image) on top of
the old chip, but connect ID2 of that chip to ground. Once that is done,
the machine should boot normally. After booting, you'll have to modify
flashrom to target the old chip or you'll simply overwrite the new chip
which would be rather undesiarable.

Please try to avoid Winbond chips if you buy a replacement. The
technical specs of the chip you want are: 4 Mbit LPC. The form factor of
the chip is probably PLCC32, but you should verify that. I've good
experiences with ST and SST chips.


> It would then be a case of removing the new chip

Not entirely. Desoldering a chip in a running board is not exactly
recommendable. Fortunately, with the ID2 trick, you can access two chips
at once.


>  (making sure the bios is set to cashable first) and reflashing with my backup.bin.

Please make sure the BIOS is _NOT_ set to cacheable. Caching in the BIOS
area is a sure-fire way to write garbage to a chip during flashing.


> But I don't know the 'bad' chip could interfere with it booting

With the ID2 trick, this should work fine.

> [...] something in the bios about 'booting' 'rom' and 'lan' [...] booting over a network, is it possible to do this with a CPU that has no bios?
>   

Unfortunately not. Basically, when you switch on your computer, RAM does
not work. The BIOS (or coreboot) takes care of switching on RAM. Without
that, booting over the network is impossible.


May I suggest you drop by on IRC in #coreboot at irc.freenode.net. Most
of us are present in that chatroom and you might get faster answers (no
guarantee about answer speed, though). It will help if you mention there
that you already sent a mail with details to the coreboot list.


Regards,
Carl-Daniel

-- 
http://www.hailfinger.org/