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On 16/12/2013 22:17, Michael Orlitzky wrote: |
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> On 12/16/2013 01:21 PM, Alan McKinnon wrote: |
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>>> |
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>>> "Enable use of the SSSE3 instruction set (NOT sse3). This is needed by |
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>>> projects which contain assembly code or which use certain compiler |
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>>> intrinsics. It is not a replacement for CFLAGS and friends." |
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>> |
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>> The second and third sentences add nothing to the description. They only |
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>> describe how cpu instruction sets in general work and are used, but tell |
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>> you nothing about ssse3. |
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> |
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> USE flags are a user interface, not documentation. A good description is |
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> one that helps the user decide, "do I want to enable this?" I'm not |
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> particular about the wording -- and my use of "needed" was a mistake -- |
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> but with that purpose in mind, a good description should contain, |
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> |
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> 1. Why might I want to enable this? |
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> |
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> 2. Why might I want to disable this? |
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> |
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> So e.g. my description is missing #2, "You should not enable this unless |
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> you have a processor supporting SSSE3." |
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> |
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> |
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>> then modifying all cpu instruction set flags similarly |
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> |
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> Yup. |
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Is it worthwhile adding a link in the description to a resource that |
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describes a USE flag in greater detail? |
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Most flags are obvious as to what they do, like jpeg/png/gif: the user |
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simply asks himself if he wants to use those formats. Most flags are |
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like this, and come down to user preference; portage merges in any |
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missing parts required |
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cpu sets are different: they also depend on whether they CAN be used in |
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a given environment. Portage cannot know if ssse3 will work for the cpu |
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running the code so cannot fill in the missing bits. The user must first |
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check if the intended cpu supports ssse3 at all (often preceded by |
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finding out how to find this out). |
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That's a lot of vital ,necessary info and it deserves the full |
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documentation treatment. A USE description is not the place for that, |
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but a link could work nicely. Especially if the linked page describes |
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the intent and usage of the USE flag in full. |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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