Date: Wed, 21 May 2003 20:13:19 -0500 From: Jeremy Messenger <mezz7@cox.net> To: Jon Lido <jlido@goof.com> Cc: freebsd-current@freebsd.org Subject: Re: gcc/libm floating-point bug? Message-ID: <oprpju0hyu8ckrg5@smtp.central.cox.net> In-Reply-To: <20030522011014.GC27806@dragon.nuxi.com> References: <200305201025.30296.jlido@goof.com> <200305201216.10964.jlido@goof.com> <20030520180004.GA2372@HAL9000.homeunix.com> <200305201512.27174.jlido@goof.com> <20030522011014.GC27806@dragon.nuxi.com>
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On Wed, 21 May 2003 18:10:14 -0700, David O'Brien <obrien@FreeBSD.ORG> wrote: > On Tue, May 20, 2003 at 03:12:27PM -0400, Jon Lido wrote: >> On Tuesday 20 May 2003 02:00 pm, David Schultz wrote: >> > On Tue, May 20, 2003, Jon Lido wrote: >> > > Well, I do have a P4, and had built everything with -march=pentium4. >> > > However, rebuilding the kernel and modules with -march=pentium3 >> produces >> > > the same results. >> > >> > This isn't a kernel problem, so you need to rebuild libm and libc >> > without -march=pentium4. You really don't want to be using the >> > Pentium 4 optimizations in gcc 3.2 anyway; the generated code is >> > generally slower. gcc 3.3 has fixes for a number of the bugs, but >> > I don't know about the performance problems. >> >> Yes, this was the problem. I rebuilt world with -march=pentium3 and >> that did the trick. > > Honest question of you -- I'll assume you're subscribed to > freebsd-current@. How have you missed all the warnings from myself and > others not to trust the -march=pentium4 optimizations? I honestly want > to know so we can figure out a better way of getting the word out. Perhaps, it should be add in the errata? Also, add the comments in the make.conf. Cheers, Mezz >> I'm not sure how CPUTYPE gets handled, but perhaps p4 should expand to - >> march=pentium3, if possible. > > I feel some will screem if we take away the ability to use > -march=pentium4 in places they know for sure will work. Unix is about > mechanisms, not policy. -- bsdforums.org 's moderator, mezz.
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