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Date: Sun, 22 Apr 2012 16:53:30 -0400
From: Richard Farina <>
Subject: Re: Build failure

On 04/22/12 16:12, Solar Designer wrote:
> Richard,
> I think this is more of a topic for john-users, but I'll reply in here
> for the already started thread.
> On Fri, Apr 20, 2012 at 04:50:36PM -0400, Richard Farina wrote:
>> He cannot build john with CFLAGS="-march=native" but has no issues with CFLAGS="-mtune=native".
> In short, if you add certain flags to CFLAGS, you must also add these
> flags to ASFLAGS and/or LDFLAGS.  In the case of -march=native (and
> certain other -march=... settings), it must be in both CFLAGS and
> ASFLAGS, so that the .c and .S files from JtR are compiled for a
> consistent target architecture (not two different ones).  In the case of
> -fopenmp, it must be in all three of CFLAGS, ASFLAGS, and LDFLAGS -
> which is readily achieved with OMPFLAGS.  Thus, as an option, you may
> specify -march=native in OMPFLAGS instead of in CFLAGS.
> I understand that in your case -march=native might come from a
> distro-wide setting that you use for packages' CFLAGS.  If so, you may
> try including that entire string in ASFLAGS as well - most of the
> options will be no-ops while assembling, but that's OK.
>> make -j1 -C src/ CPP=i686-pc-linux-gnu-g++ CC=i686-pc-linux-gnu-gcc AS=i686-pc-linux-gnu-gcc LD=i686-pc-linux-gnu-gcc 'CFLAGS=-c -Wall -include \"/var/tmp/portage/app-crypt/johntheripper-1.7.9-r2/work/john-1.7.9\"/config.gentoo -O2 -march=native -pipe -fPIC -fPIE -fopenmp' 'LDFLAGS=-Wl,--hash-style=gnu -Wl,-O1 -Wl,--as-needed' OPT_NORMAL= OMPFLAGS=-fopenmp linux-x86-sse2
> You dropped -fomit-frame-pointer and added -fPIC -fPIE there.  These
> changes relative to JtR's default flags may have performance impact
> (likely exceeding the possible advantage of -march=native).  It would be
> better to just use JtR's defaults.
> Starting with gcc 4.6.x, -fomit-frame-pointer became the default for -O2
> when building for 32-bit x86, though.  Since Gentoo uses fresh stuff,
> you're probably lucky to benefit from this.  Yet a while ago it was a
> real problem (distros overriding CFLAGS, thus not including
> -fomit-frame-pointer and incurring performance hits of up to 10% or so).
> -fPIC -fPIE are still a bit problematic, although I understand why
> Gentoo is doing that.  You may try a relbench of a Gentoo build vs.
> default build of jumbo.  I suspect that the Gentoo build would run
> slower on average.  You may try it separately for x86_64 and i686 (also
> for different make targets and OpenMP or not if you like).
> I hope this helps.
Thank you very much for your response on this, it has been enlightening
to say the least.  I'll goof around and see what I end up with, any
further issues like this will be pushed to the users list instead of the
dev list.


> Alexander

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