[OLPC-devel] Embedded Controller and Serial Flash ROM

[Mark J. Foster]

Hi, Carl [& Ray]!

*Carl:* I'm CCing the expert, Ray Tseng, the manager of the BIOS group 
at Quanta, to help address your questions regarding the EC.  My primary 
goal with this note was just to get this conversation started!

A quick scan through the 8051-based KB3920's data sheet suggests that it 
continually executes code from the external Flash ROM, so I don't 
believe that it'll be possible to compress the EC's BIOS image.  The 
data sheet also says that the KB3920 can address 64K of RAM, as four 
separate 16K pages (i.e. bank switching).

*Ray*: Can you help answer Carl's questions?  One point that I'd ask is 
that you talk to ENE about fully releasing the KB3920's data sheet - the 
one that I have is stamped "CONFIDENTIAL".  Can you please ask ENE for 
one that does not have the "CONFIDENTIAL" stamp on the pages?  In 
addition, please supply a pointer to your current EC image (even though 
it is not complete). Thank you very much!

Cheers!
Mark

Carl-Daniel Hailfinger wrote:
> Can't the EC use only 32k? And when exactly does the EC read its code?
> Before the BIOS is run? If so, can we load the EC code after the BIOS?
> Which vital functions are performed by the EC and can we split them
> from non-vital functions (if any)?
>
> Can you attach the current EC code (even if it doesn't work)? If it
> is possible to execute that code during or after BIOS init, we can
> compress it and probably save >50% of space.
>
>