[OpenBIOS] OpenBIOS and ppc64?

Andreas Färber andreas.faerber at web.de
Fri Oct 1 00:57:17 CEST 2010

Am 01.10.2010 um 00:42 schrieb Alexander Graf:

> On 01.10.2010, at 00:37, Andreas Färber wrote:
>> The easiest would be if I would find out how to configure a multi- 
>> lib ppc/ppc64 gcc-4.4.x, so that we can compile a ppc64 version  
>> using `make EXTRACFLAGS=-m64`.
>> Otherwise we'd need to provide a separate cross-ppc64 config file  
>> and hack switch-arch to drop the "64" at some point so that it  
>> builds in obj-ppc64 but uses code from ppc...
> You don't need to compile 64 bit code to address 64 bit physical  
> addresses. Just map them to 32 bit addresses and you're good from  
> the existing code base.

Not in real mode iiuc. Unless of course we keep switching on and off  
the MMU, which sounds kind of scary to me.

The idea is that OpenBIOS contains RTAS code (start.S), AIX allocates  
memory for it, calls rtas-instantiate (methods.c), we copy it there  
and later AIX might even unmap OpenBIOS while continuing to use RTAS.  
It might as well change the MMU mappings at that point, so we do need  
code that works in real mode.


> The only thing that needs to change is the physical address variable  
> type of the alloc function. That has to become uint64_t.
> Alex
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