[openfirmware] OFW x86 MMU Setup

Andrea r&d4 at dave-tech.it
Fri Jun 20 17:13:01 CEST 2008



Mitch Bradley wrote:
> Okay, having reread the LPC FLASH chip manual, I see what is happening.  
> (My intuition about LPC FLASH devices is deficient because I took a 
> break from doing firmware during the period when Intel was inventing FWH.)
> 
> The virtual address range that OFW uses - see pc/virtaddr.fth : 
> fw-virt-base , fw-virt-size - overlaps the physical address range that 
> LPC FLASH chips use.  I probably would not have picked that virtual 
> range had I realized that LPC devices decode more address space than 
> they use for the data array.
> 
> Address conflicts like this is one of the reasons why virtual=physical 
> address assignment is problematic.
> [snip]

Thanks for the clear explanation Mitch.
I tried to use dynamic virtual address allocation but I have the same 
problem, which (IMHO) is a confirmation that the trick is at lower lever 
  than virtual addressing.

Thanks anyway & best regards,

-- 

Andrea

DAVE Srl - Electronics System House
e-mail address: r&d4 at dave-tech.it




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