[OpenBIOS] OpenBIOS and ppc64?

Andreas Färber andreas.faerber at web.de
Fri Oct 1 00:29:35 CEST 2010

Am 01.10.2010 um 00:25 schrieb Alexander Graf:

> On 01.10.2010, at 00:09, Benjamin Herrenschmidt wrote:
>> On Fri, 2010-10-01 at 00:03 +0200, Alexander Graf wrote:
>>> If I understand the U3 and U4 designs correctly, PCI is always bound
>>> to be within the first 32 bits. Copying Ben for verification. I  
>>> don't
>>> really remember having seen 64 bit cells on any Power system either,
>>> but I could be wrong. Again, let's ask the expert here :).
>> Yes. However, on js2x, the firmware plays funny remapping tricks...
>> In general, however, OpenBIOS should be fixed. It's getting more  
>> common
>> to have even 32-bit machines with physical devices above 32-bit (even
>> ARM is now growing an equivalent of PAE for that, and almost all 4xx
>> powerpc do that).
> So how does the firmware tell the OS that a device is on a 64 bit  
> physical address if it only knows about 32 bit wide cells?

By concatenating two 32 bit wide cells in Big Endian order, it seems. :)


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