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Michael Weyershäuser <thedude0001@×××.de> posted 4564F0D8.8030904@×××.de, |
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excerpted below, on Thu, 23 Nov 2006 01:52:40 +0100: |
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|
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> Jack Lloyd wrote: |
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>> I would think it would still be useful to have know, so the ebuild |
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>> could use filter-flags to prevent this problem from occuring for |
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>> others (if it is in fact a CFLAGS problem). |
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> |
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> It might depend on the flag we're talking about, but filter-flags and |
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> replace-flags is mostly used for ebuilds that don't work with supported |
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> flags (like an ebuild that doesn't like -Os but needs -O2). There has |
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> been a debate a couple of weeks back if ebuilds should even filter |
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> -ffast-math as this is a flag that breaks dozens of packages, sometimes |
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> in sneaky, hard-to-debug ways, or if the ebuild should just die if it |
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> finds that flag. |
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> |
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> You're free to try, but the idea is that while you have a lot of choices |
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> when using Gentoo it is not the devs duty to stop you from making bad |
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> choices or protect you from their effects. |
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|
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FWIW, while I use somewhat "interesting" cflags, I'd certainly be for |
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dieing at a global portage level (so the ebuild doesn't have to worry |
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about it at all) with -ffast-math. That one's simply not safe for general |
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use, as the gcc manpage makes quite clear. Individual builds can and do |
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often add it themselves if it's safe and useful for the package to do (as |
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is the case with many video or visualization packages, for instance). |
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|
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For others, it depends on the dev/maintainer. Some of them are OK with |
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certain flags, some not. It helps if one is aware of the situation and |
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already knows to try with the accepted-safe -O2 -pipe -march=<arch> flags, |
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only, before reporting a bug. If it's a bug that might be CFLAG |
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sensitive, I do so. Only once have I had a bug closed incorrectly, for |
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CFLAGS that quite obviously had nothing at all to do with the problem. |
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(In that case, it was a multilib-strict error due to a file going to lib |
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that should have gone to lib64, obviously a file placement error unrelated |
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to CFLAGS. I refiled at the next version bump when the issue still wasn't |
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fixed, and it was fixed within minutes... literally.) The rest of the |
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time, I've usually tried before filing if it looks to be CFLAG sensitive, |
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tho I think I've had one closed where it was questionable early on -- I |
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simply tried with the requested CFLAGS and reopened. |
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|
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More often, I don't file bugs because there's no way to isolate the issue |
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given my CFLAGs. The latest example, I was having issues with glibc-2.5 |
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and reverted to 2.4-r4 (gotta hack portage to do it, due to a sanity check |
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normally preventing glibc downgrade, but it worked), that I didn't file a |
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bug on as I could never satisfy myself that there wasn't a dependency I'd |
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missed and I didn't want to emerge --emptytree the packages in question to |
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find the issue. I /suspect/ the problem is a memory allocation race |
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condition, probably SMP specific and possibly amd64 specific, with |
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optimizations in glibc-2.5 that weren't there in 2.4. The affected |
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packages here were all audio/visual, amarok, xmms (before its removal), |
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kaffeine, but NOT kmplayer, for whatever reason. It wasn't xine-lib |
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specific since xmms was affected and kmplayer wasn't. Note that glibc |
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itself is already filter-flagged to nearly -O2 -pipe -march=<arch> on its |
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own, so it's not likely to be the problem. Never-the-less, I remerged |
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glibc, gcc, kdelibs, kaffeine, amarok, and xine-lib, all with "safe" |
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cflags, bug still existed with glibc-2.5 but /not/ glibc-2.4-rX, but I |
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couldn't isolate it beyond that, so I didn't file the bug. I |
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package.masked =glibc-2.5, so when 2.5-r1 comes out I'll tackle the |
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problem again. |
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|
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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 |
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|
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-- |
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