Date: Tue, 09 Nov 2004 00:31:34 +0000 From: Colin Percival <colin.percival@wadham.ox.ac.uk> To: current@freebsd.org Cc: kan@freebsd.org Subject: RFC: Building libstdc++ with -frandom-seed=RepeatabilityConsideredGood Message-ID: <41900FE6.1060602@wadham.ox.ac.uk>
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I would like to add the following line to lib/libstdc++/Makefile: CFLAGS+= -frandom-seed=RepeatabilityConsideredGood This is a new option in gcc 3.4 which allows a string to be specified (in this case, the string "RepeatabilityConsideredGood") which will be used as a random number seed in place of the usual behaviour (obtaining a seed from the clock). At present, libstdc++ is the only part of FreeBSD which does not build "recognizably" repeatably. By this I mean that while many files contain timestamps (including all library archives), libstdc++ currently has much greater variation from one build to the next, because it happens to tickle a place in gcc where the random number seed is used. In previous FreeBSD releases, this behaviour was exhibited by the libobjc library. My personal interest in this is for FreeBSD Update -- I need repeatable builds in order to identify which files are affected by security patches -- but since I can't see any downside to using this option, I'd like to commit this instead of keeping it as a local patch. Opinions? Colin Percival
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