common flash hw write enable methods

[Ronald G. Minnich]

On Sun, 1 Dec 2002, Andrew Kohlsmith wrote:

> Now I imagine that these are tied to a MOSFET to +12V which is run off of a 
> GPIO pin. 

probably a good guess.

Another way I found it on one board was to try every combination of GPIOs 
until the FLASH started working. Not fun, but pretty fast if you write a 
program.

> I can always cut the traces and hard-wire to +12V but I'd like to see if I 
> can't do this programmatically.  I have a number of boards I want to use and 
> hardware hacking is something I'd like to avoid doing if possible.

get the flash burner for this board, run under a simulator of some sort, 
and watch the IOs. Or put a PCI bus analyzer on the machine, run the flash 
program, and watch the IOs. It's not going to be fun.

I still don't see how running under Bochs helps with the chipset but maybe 
I missed something. 

> Now I know that every motherboard is different and that there may be other 
> things locking me out, but generally speaking is there an "industry standard" 
> way of enabling/disabling BIOS reflash?  

No, the goal is to make it hard for you to reflash. So the vendors keep 
coming up with new ways to hide this. Very annoying!

ron