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