Date: Sat, 27 Jul 2002 19:19:45 -1000 From: Clifton Royston <cliftonr@lava.net> To: freebsd-stable@FreeBSD.org Subject: Is use of -O2 still deprecated for buildworld in -stable? Message-ID: <20020727191945.A10231@lava.net>
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I had a vigorous discussion about this with a colleague on Friday
(yesterday.) We're trying to agree on the proper set of options to use
in /etc/make.conf for doing "buildworld" and/or "buildkernel" i386
servers (Pentium 3.)
These machines will be running production services for our customers,
so they need to be high-reliability; we're running 4.5-release and
4.6-release CVSuped to those tags, not trying to track -stable.
My colleague is insistent that because -O2 in gcc will generally
produce much better code, we should be using it if it's at all possible
and safe. He also was frankly disbelieving that there could be serious
bugs in the optimization at the -O2 level because gcc is used so
extensively in the Linux world, almost always with -O2.
My understanding is that whether or not -O2 *should* produce exactly
equivalent code to -O, there are recurrent reports of people having
trouble doing a buildworld with -O2 in -stable or in 4.x release
trains, where their problems go away when they revert back to -O. In
this case, we simply shouldn't be using it on production servers. I'm
using it on my home machines (-O2 for world, -O for kernel) but they
has altogether different needs for reliability.
Am I correct in this, or are the warnings about -O2 in make.conf
obsolete, or are they only applicable to non-i386 architectures, or to
the kernel, or to -current? Can someone straighten me out here?
-- Clifton
--
Clifton Royston -- LavaNet Systems Architect -- cliftonr@lava.net
"What do we need to make our world come alive?
What does it take to make us sing?
While we're waiting for the next one to arrive..." - Sisters of Mercy
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