[LinuxBIOS] booting from PCI bus card

Bari Ari bari at onelabs.com
Sun Apr 29 20:28:37 CEST 2007

Quux wrote:
> that is the point - the issue was discussed here a couple of days ago.
> a regular PCI expansion BIOS is called too late during POST by legacy 
> BIOS. The Altera MAXII has a patch field to put a flash mem into.
> this PCI space mapping business is the key point. chipset's provide for 
> booting from PCI space but I wonder whether they need to be told to do 
> so by a hardware switch / signal or whether a small patching of legacy 
> bios would do the trick.   --Q

What is the actual problem here? Accessing factory BIOS write enables 
when the mainboard vendor has enabled "security through obscurity" 

If so reverse engineer their flash BIOS write enable method or get out 
the soldering iron and bypass the write enable garbage and enable it 
with a switch/jumper or unused chipset gpio and a pull-up/down resistor.

Trying to have control from PCI space via IPL BIOS ROM isn't supported 
by every chipset and does not give you full control of the hardware. How 
much control do you want/need and do you really need that chipset 
supported? Isn't it simpler and lower cost to just solder a few 
connections vs using a PCI FPGA card that costs more or equal to the 

The software reverse engineering method takes more time initially but 
then it's easy later to modify thousands of machines in a cluster or 
application. If there is enough money for Intel to be interested in 
supporting you they will. If there is not enough interest, is your 
project really just a hobby and isn't reverse engineering part of the fun?

The hardware method is easy for a board or two but lots of time later 
for a thousands of boards.


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