[LinuxBIOS] SPI flash focus

Segher Boessenkool segher at kernel.crashing.org
Fri Nov 24 16:22:50 CET 2006

> Unfortunately it requires some special characteristics in the board
> schematic, to not risk destroying the chipset.
> "Warning: please do not try to use SF100 directly on the application
> system if the scenario is not in the above two cases."
> ..from their manual. I agree with them, it could be dangerous to
> drive the SPI chip while it's connected if you don't know exactly how
> it is connected and that it really is safe on that particular board..

The only thing that is required is that they can safely pull the
HOLD# pin to ground.  Any sane design will have a pull-up resistor
on that line (and most other SPI lines, for that matter).  That
said, there probably _are_ boards that do not have a sane design.
Such a shame.

[Oh, it obviously also doesn't work if the chipset or the motherboard
design uses HOLD# for something else already.  This isn't commonly
done though].

Aaaaaanyway...  It is really simple to build a device like this
yourself for a few bucks.  SPI flash has many nice characteristics.


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