Date: Tue, 08 Mar 2011 01:15:44 +0100 From: Martin Matuska <mm@FreeBSD.org> To: George Liaskos <geo.liaskos@gmail.com> Cc: Alexander Best <arundel@freebsd.org>, freebsd-current@freebsd.org Subject: Re: r219385 build error. Message-ID: <4D757530.9050505@FreeBSD.org> In-Reply-To: <AANLkTi=BrjRteOFLAN1wvfOoO7n38WRY7DcHuMT5mSzw@mail.gmail.com> 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> <AANLkTi=BrjRteOFLAN1wvfOoO7n38WRY7DcHuMT5mSzw@mail.gmail.com>
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This change did NOT add SSSE3 or any other new instruction sets to our
base compiler.
The only change of using -march=core2 vs -march=nocona is actually
different instruction costs that may result
in binaries more optimized for your core2 and later CPUs (and less
optimized for nocona and earlier CPUs - but they will run there if the
CPU supports sse3).
We support newer instruction sets for base compiling starting with the
latest base binutils upgrade and
that is available only in CURRENT.
I might take a look at the possibility of backporting SSSE3, but that is
a way more intrusive change than this one. I will also run some more
benchmarks.
Dňa 08.03.2011 00:14, George Liaskos wrote / napísal(a):
>> "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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