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Hi all, |
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Back in May 2005 we made the decision to not use the assembler USE flags |
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because AMD64 was not affected by the "lots of sub-arches" problem and |
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instead just enable SIMD code where possible. As a result of this, the |
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3dnow, 3dnowext, mmx, mmxext, sse and sse2 USE flags got masked. |
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This decision turned out to be not the best. Intel's EM64T processors |
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don't support 3dnow and 3dnowext, there are AMD64s with and without SSE3 |
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support. The "one size fits all" idea simply is no longer true. Starting |
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with portage 2.1.2_pre3-r4, there is support to force USE flags on or |
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off on a per-package basis. This means less ebuild hackery for us, and |
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so I went and checked the ~50 packages with mentioned USE flags. |
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The result is that the assembler USE flags convey their actual meaning |
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again IF AND ONLY IF you use >=portage-2.1.2_pre3-r4. I suggest you to |
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stick at least "mmx mmxext sse sse2" into your USE flags, as this is the |
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common denominator of all AMD64s. If your processor supports it, 3dnow |
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and 3dnowext might be worth adding too. |
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*For users of portage versions prior to 2.1.2_pre3-r4 nothing changes*, |
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but I'd still recommend to add the USE flags. They will become effective |
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as soon as you upgrade portage. |
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In a nutshell: |
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1. add "mmx mmxext sse sse2" to your USE flags |
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2. emerge -u portage |
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3. emerge -NuD world |
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If you experience any build failures, please file a bug report on |
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http://bugs.gentoo.org/ |
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Thank you for your attention, the team wishes you a convenient flight. |
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-- |
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Kind Regards, |
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Simon Stelling |
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Gentoo/AMD64 developer |
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-- |
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gentoo-amd64@g.o mailing list |
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