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JimD posted <20060326113037.63d2f7f3@××××××.localdomain>, excerpted below, |
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on Sun, 26 Mar 2006 11:30:37 -0500: |
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> What does (-multilib) mean? I tried to unmask it but I cannot figure out |
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> how to get multilib turned on. |
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> |
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> P.S. I have also seen the (-FOO) syntax before and cannot figure out how |
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> to enable a USE option that is in that format. |
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I see SS's pointing to the FAQ, and that's correct, but I read the blurb |
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in the FAQ and don't find it worded as clearly as it could be. |
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In general, a USE flag in parenthesis, as (-multilib), indicates that USE |
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flag is set by the profile and can't be changed. (Well, it could be, but |
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you better be very sure you know what you are doing, and as with many |
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things in life, if you are asking, you don't.) |
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Why would this be? Simple. The regular amd64 profiles require multilib, |
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altho there are subprofiles available that have it disabled, if you |
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prefer. Thus, it's part of the profile, enabled or disabled by the |
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profile you use, and not settable separately. (This is a fairly new |
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situation. Old 2004 profiles had it as a settable USE flag, which is why |
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it still exists as a USE flag, even if it can't be set as such.) |
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Similarly with some other flags, including mmx, sse, etc. All amd64 based |
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processors, both those from AMD and those from Intel, include these |
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extensions, so gcc knows they can be used already, and the flags need not |
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be specified. Additionally, as the flags were developed on 32-bit |
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processors, they often invoke the 32-bit specific assembly language |
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extensions. Trying to use these 32-bit specific extensions in a 64-bit |
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program is a sure way to failure, so all around, it's simply better to |
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force the USE flags off for 64-bit mode. Again, gcc already knows it can |
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use the 64-bit versions, and the USE flags apply the 32-bit versions |
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which will break stuff in 64-bit mode, so leave them off, and nobody gets |
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hurt. <g> Do note, however, that if you use a 32-bit chroot, you can |
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safely use those flags there, and they'll work as intended, because the |
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chroot will be using a 32-bit profile, not the usual 64-bit profile. |
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Perhaps this is clearer than the way the FAQ says it? |
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-- |
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Duncan - List replies preferred. No HTML msgs. |
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"Every nonfree program has a lord, a master -- |
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and if you use the program, he is your master." Richard Stallman in |
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http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html |
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-- |
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gentoo-amd64@g.o mailing list |
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