[PATCH] powerpc: Fix problems with 32bit PPC's running with more than 2GB of RAM

Benjamin Herrenschmidt benh at kernel.crashing.org
Sat Jul 12 13:33:54 EST 2008


> Are you *sure* you can see all 4GB?  I thought we lost some of the 32- 
> bit PCI address space for PCI IO......  Disclaimer: I'm no expert on  
> PCI :)

You are right. I didn't think that through when I replied. We do lose
some of it for MMIO (not IO). So we cannot really go all the way to 4G
because we can't DMA to all of it, right.

> FYI, I'm *very* close to having swiotlb fully functional on powerpc to  
> support larger RAM - I am able to boot with 6GB on 8641 right now.   
> There are some bugs that I'm still shaking out - I hope to push this  
> out in the next couple of weeks.

That won't make .27 then ?

Cheers,
Ben.





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