Re: PowerPC 970 (G5) 64-bit support

[Michael <macallan%netbsd.org@localhost>]

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Hello,

On Apr 11, 2011, at 6:26 PM, Erik Fair wrote:

> Are the required changes sufficient to warrant a new port, e.g.  
> macppc64?

All the cpu-specific stuff lives in arch/powerpc and what's in macppc  
is what's actually Apple-specific. Some bits of the powermac  
architecture actually made it into the G5, like for example the audio  
DMA machinery.

> I have no particular desire to dive into MMU code; my skills &  
> understanding of that realm are more than a little rusty.

There's already a 64bit pmap.c. What's missing is code to properly get  
the CPU into 64bit mode in order to set up the initial vm stuff ( even  
with bridge mode we need to be in 64bit mode to do pretty much  
anything MMU-related ) - everything else should be fairly minor,  
except maybe support for the host bridge's iommu. In bridge mode we  
could just ignore that since we wouldn't use any RAM above 4GB anyway.  
And even with 64bit we could initially just make sure any DMA memory  
is allocated from the lowest 2GB.
That said, I'm fairly sure I could get the rest of the machine going  
( I have a dual 2GHz PCIe G5 ) once someone helps getting it past the  
initial MMU setup, that's where I got stuck the last few times I tried.

have fun
Michael

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