a couple of questions to powerpc folks

Ken Moffat ken at kenmoffat.uklinux.net
Wed Jul 27 02:51:27 PDT 2005

On Wed, 27 Jul 2005, ;)- wrote:

> hi community! i'm going to build on g4 machine. so my questions are:
> * what compile-time optimizations are good (for performance) for this
> architecture?

 Well you could start with -O2 -mcpu=7450. {-Os or -O3 if you have
religious objections to -O2} Really, I've never found anything on modern
equipment that was worth the effort of rebuilding and benchmarking.

 I've tried the supposedly useful -mpowerpc-gfxopt -fsigned-char
-mstring -mmultiple but something refused to build (X, I think), so I
dropped them.

 You could pass -maltivec -mabi=altivec but I think most, or all, of the
packages that will benefit from this already turn it on in configure.

> * do i have any choise with bootloaders, or nothing but yaboot?
> thanx in advance.

 Use whatever bootloader works.  For New World macs, that's yaboot - so
I guess that is your only choice.  Other boards (particularly embedded)
use other bootloaders, e.g. uImage (plus 'dd' to transfer the kernel to
the boot partition).  Old World macs are different too.

 das eine Mal als Tragödie, das andere Mal als Farce

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