Date: Tue, 8 Mar 2011 01:14:49 +0200 From: George Liaskos <geo.liaskos@gmail.com> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: r219385 build error. Message-ID: <AANLkTi=BrjRteOFLAN1wvfOoO7n38WRY7DcHuMT5mSzw@mail.gmail.com> In-Reply-To: <20110307225652.GA61509@freebsd.org> References: <AANLkTikc-Z9mjmQ7EWnWdqz297hHQ_Kt2k9z05FaNv-y@mail.gmail.com> <20110307205957.GA47557@freebsd.org> <AANLkTimJpsr=38UPswCXUmajNixTs1qS-8FxT36xAK4V@mail.gmail.com> <20110307214935.GA53914@freebsd.org> <AANLkTinfQv3y0yohB4qtRL9JOktqa76SvB%2Bw0WpEzAXh@mail.gmail.com> <20110307225652.GA61509@freebsd.org>
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> "native" doesn't get handled by bsd.cpu.mk at all! it gets passed to gcc
> directly and gcc choses -m{tune,arch} on it's own.
>
> don't add -march=* directly to CFLAGS. this is bound to go wrong at some
> point. use CPUTYPE to set the cpu and CFLAGS for -O*, -pipe, etc.
>
> also please keep in mind that the optimisations that can be achieved by
> finetuning make.conf are rather minor. some people think that with
> cflags and cpu juju they can boost the OS. i don't believe that's true. the
> chances are much greater that you're adding a problematic switch and end up
> with binaries during installworld that segfault. so it's not really worth
> getting into this kinda trouble just for the sake of optimisation.
>
> a simple
>
> CPUTYPE ?= native
> COPTFLAGS = -O0 -pipe
> CFLAGS = -O2 -pipe
>
> should be close to perfekt. ;)
>
> cheers.
> alex
Thank you again.
It's not so much about the base system but the ports. Now that the
assembler and binutils support newer SIMD commands it makes sense to
exploit them, I know that they are not used during kernel compilation.
Using newer / different compiler from ports makes things more complicated.
.
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