> > A useful pointer - thanks. But it seems to assume that we use Athlon XP > processors (FLAGS="-O2 -march=athlon-xp -msse2 -pipe > -fomit-frame-pointer"). My box has Opterons, so I assume I should > substitute "-march=opteron", no? > > I've found explanations a bit thin on the ground as to what the C arch > flag and the chost definition do. It's generally true that an > explanation is far better than an instruction if you want to avoid > supplementary questions :-)
An excerpt from http://www.gentoo.org/proj/en/base/amd64/technotes/index.xml?part=1&chap=3 : "Unlike gcc 3.3, gcc 3.4 requires that you set -march. The most conservative (and supported) CFLAGS can be set as show below: ... CFLAGS="-march=k8 -O2 -pipe" ... Note: -march=k8 equals -march=athlon64 equals -march=opteron." Here is an excerpt from http://www.gentoo.org/proj/en/base/amd64/technotes/index.xml?part=1&chap=4 : "Once gcc-3.4 is released, you should be able to use -march=k8 to optimize for the amd64, but it's not mentioned in the changelog if this is available for 32-bit compilation as well." So for the 64-bit install, using k8, athlon64 or opteron will produce the same binaries. For the 32-bit chroot, you should use athlon_xp as that is the most conservative setting for running in 32 bit mode on the k8 architecture. Random Thought: --------------- Q: What do they call the alphabet in Arkansas? A: The impossible dream. -- [email protected] mailing list
