Date: Wed, 13 Sep 2006 11:05:44 +0200 (CEST)
From: Oliver Fromme <olli@lurza.secnetix.de>
To: freebsd-stable@FreeBSD.ORG
Subject: Re: optimization levels for 6-STABLE build{kernel,world}
Message-ID: <200609130905.k8D95idk062789@lurza.secnetix.de>
In-Reply-To: <20060912161603.R1031@ganymede.hub.org>
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Marc G. Fournier <freebsd@hub.org> wrote: > What are ppl currently using for CFLAGS/COPTFLAGS in /etc/make.conf for > building kernel/world? I know awhile back it wasn't recommended to go > above -O2, for instance, but suspect that has changed ... ? The best optimization is probably to not override the defaults at all, because they're already pretty optimal. In fact, by overriding the defaults there's a good chance to make things worse. :-) The default CFLAGS are "-O2 -pipe -fno-strict-aliasing". Anything above -O2 isn't supported, and using -O2 without -fno-strict-aliasing also isn't supported (and will create broken code for some programs). A common mistake is to specify CFLAGS="-O2 -pipe" and omit -fno-strict-aliasing. That'll shot you in the foot sooner or later. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.'
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