Date: Tue, 8 May 2001 00:53:03 +0200 From: Erik Trulsson <ertr1013@student.uu.se> To: freebsd-stable@FreeBSD.ORG Subject: Re: CFLAGS Optimization Message-ID: <20010508005303.A7567@student.uu.se> In-Reply-To: <20010507230417.F508-100000@gateway.bogus>; from nuno.mailinglists@pt-quorum.com on Mon, May 07, 2001 at 11:36:31PM %2B0100 References: <20010507230417.F508-100000@gateway.bogus>
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On Mon, May 07, 2001 at 11:36:31PM +0100, Nuno Teixeira wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hello to all, > > I came from Linux and at that time I used CFLAGS to optimize general > programs and linux kernel. > > For example: > > [i686]: > CFLAGS='-O9 -funroll-loops -ffast-math -malign-double -mcpu=pentiumpro > - -march=pentiumpro -fomit-frame-pointer -fno-exceptions' You do know that gcc doesn't have any optimization-level above -O3 ? It is therefore fairly pointless to specify stuff like -O4 or -O9 > > [i586]: > CFLAGS='-O3 -mcpu=pentium -march=pentium -ffast-math -funroll-loops > - -fomit-frame-pointer -fforce-mem -fforce-addr -malign-double > - -fno-exceptions' > > [i486]: > CFLAGS='-O3 -funroll-all-loops -malign-double -mcpu=i486 -march=i486 > - -fomit-frame-pointer -fno-exceptions' It is pointless to use both -mcpu=X and -march=X since -march=X implies -mcpu=X. > > Can I use CFLAGS on FreeBSD too? If I put the CFLAGS on > /etc/defaults/make.conf, the kernel is affected by it? > Does CFLAGS can optimize programs and kernel on FreeBSD OS? > Yes, you can use CFLAGS on FreeBSD. For the kernel you should use COPTFLAGS instead. Don't modify /etc/defaults/make.conf. Use /etc/make.conf instead. Finally a warning: using -O2 and -O3 is known to produce bad code sometimes. If you compile with any optimization flags other than -O you should not expect to get much help if anything breaks. (Other than the advise to use a plain -O instead.) -- <Insert your favourite quote here.> Erik Trulsson ertr1013@student.uu.se To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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