G5 using ppc32 not ppc64 kernel?

[Tamblyne]

Hi Dan,

I noticed you mentioned that everything was 32bit not 64 bit so far for the 
G5.

I thought ppc64 was well supported in both the kernel and in the tool chain 
(gcc, glibc, binutils etc) already?    Is the G5 that different from the 
ppc64 arches that IBM already supports?

Also, the ABI for linux ppc32 and linux ppc64 are quite different.  

Linux ppc64 seems to be a minor variation of AIX, abi-wize which means it has 
inherited some silly/old structure layout issues (i.e doubles are not aligned 
to 8 and instead are aligned to 4 in structures but 64 bit ints are properly 
aligned).  Small structures are returned in registers, etc.   

Also I recently added support for the -malign-natural extension for ppc64 
(patches exist for gcc 3.3 and changes have been integratedinto gcc for 3.4) 
so that structure layout matches that of ppc32 and most other architectures 
(most either have max align of 4 or they allow natural alignment for higher 
performance (such as ppc32)

Using -malign-natural  is actually a requirement for OOo to build and work on 
both MacOSX using gcc 3.3 and will be for ppc64/AIX as well.

So when YDL does produce a ppc64 OS please consider making -malign-natural the 
default via gcc-spec for both performance reasons and for compatibility with 
other architectures.

Thanks,

Kevin