[OpenBIOS] r638 - in trunk/openbios-devel/forth: bootstrap device

Tarl Neustaedter Tarl.Neustaedter at Sun.COM
Fri Dec 4 01:58:33 CET 2009

Mark Cave-Ayland wrote:
> Tarl Neustaedter wrote:
>>> Continuing to work on Milax, I've found out that the infinite loop 
>>> bug I'm getting here is because of an MMU problem - two different 
>>> virtual addresses appear to be mapped to the same physical address. 
>> I believe that's legal. I know that OBP used to do that on sun4s 
>> systems.
> Oh that's interesting to know; however in this case I'm fairly 
> confident it's broken :(  What happens is that first the volume 
> descriptor is read from the ISO image into a special buffer, and 
> subsequent reads for file entries should then go into a different 
> buffer. Unfortunately the subsequent reads into the second buffer seem 
> to be mapped to the same memory location

Ah. So the problem isn't that you have two virts->one phys, but that you 
expect your two virts to have different physical backing, and they don't.

Yup, that's a bug :-)

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