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On 19.02.2012 20:06, "Tóth Attila" wrote: |
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> The email I replied to was originally posted by "Hinnerk van |
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> Bruinehsen". |
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> |
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> Let's see my question in details, that might clarify it. Here is |
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> the part of the ebuild I'm asking questions about: |
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> |
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> " if [[ $(gcc-major-version) -lt 4 ]]; then append-cxxflags |
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> -fno-stack-protector elif [[ $(gcc-major-version) -gt 4 || |
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> $(gcc-minor-version) -gt 3 ]]; then if use amd64 || use x86; then |
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> append-flags -mno-avx fi fi " |
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> |
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> Break it down: |
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> |
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> " if [[ $(gcc-major-version) -lt 4 ]]; then append-cxxflags |
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> -fno-stack-protector " The first part is a historical remnant from |
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> times before Zorry. We used gcc-3.4.6 for a long time. It used a |
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> different implementation for SSP. |
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> |
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> " elif [[ $(gcc-major-version) -gt 4 || $(gcc-minor-version) -gt 3 |
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> ]]; then if use amd64 || use x86; then append-flags -mno-avx fi fi |
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> " |
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> |
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> The second part disables avx optimisations if the gcc version is |
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> newer than 4.3. However avx support isn't around so long and it's |
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> not mature. Avx is an instruction set extension, that is getting |
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> some attention lately. I'm lucky to have a system, with a capable |
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> processor. The block disabling the optimisations resides right |
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> besides the stack-protector statement. That's why I thought some |
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> hardened floks put it there. And I'm curious about the reason. |
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> |
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> Of course it might be simply there, because enabling avx |
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> optimizations can actually decrease performance. Like you can see |
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> it here: |
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> http://www.phoronix.com/scan.php?page=article&item=intel_avx_gcc&num=1 |
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> |
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> Security is more important for me compared to speed. That's why |
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> I'm interested in any security effect of a compiler option (like |
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> creating textrels or so). If it's a security problem, I won't use |
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> corei7-avx, but rather go for simple corei7. |
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> |
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> Regards: Dw. |
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|
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Hi, |
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|
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that part is in the normal icecat-ebuild in the tree. It's also within |
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the firefox ebuild. |
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I don't know if it's needed, but mozilla herd as maintainers may be |
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the right people to ask. |
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|
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Regards, |
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|
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Hinnerk |
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|
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