Re: [Qemu-devel] Re: compile qemu for a G5

[André Braga]

On Mon, 11 Oct 2004 06:32:44 -0700, Fred Hope <address@hidden> wrote:
> So for my iMac G5 1.8 GHz it would be -mcpu=970 or what?  The only
> thing I know about the G5 is that it is really the PowerPC 970.  Also,
> I use this flag when I run ./configure, right?  Not the "make" command
> itself?

-mcpu=power4 is the correct flag. As of January there was a bug in GCC
regarding this flag and 64-bit code, so I suggest looking for updates
if your xcode tools happen to be somewhat old.

Other than that, G5 behaves better if code is aligned to 32 byte
boundaries, because of the longer cache lines. Those flags may help:
-falign-functions=32, -falign-labels=32, -falign-loops=32,
-falign-jumps=32. They will potentially make the executable fairly
large, though, which may or may not be a problem for you.

Also take a look at these pages and their links:
http://developer.apple.com/technotes/tn/tn2087.html
http://developer.apple.com/performance/g5optimization.html

Back in June there were some issues with the configure file flags
being completely ignored by some makefiles, and I sent a patch to the
list, but I don't know if they were applied (haven't been able to work
with the sources since then), so I suggest looking at the makefiles
for places where those flags should appear but end up not showing at
all.


cheers,
A.




-- 
"A year spent in artificial intelligence is enough to make one believe in God"
Alan J. Perlis