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Date:      Thu, 15 Aug 2013 21:12:52 +0200
From:      Dimitry Andric <dim@FreeBSD.org>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        "freebsd-current@freebsd.org CURRENT" <freebsd-current@FreeBSD.org>, Dmitry Morozovsky <marck@rinet.ru>, Peter Wemm <peter@wemm.org>
Subject:   Re: building i386 world on amd64 host: failed @svn
Message-ID:  <D559C583-B0A9-4731-B454-3521635AEC79@FreeBSD.org>
In-Reply-To: <20130815183640.GR4972@kib.kiev.ua>
References:  <alpine.BSF.2.00.1307281713160.55051@woozle.rinet.ru> <17A40261-A0DA-4070-990F-0D0777A5BE44@FreeBSD.org> <20130815183640.GR4972@kib.kiev.ua>

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On Aug 15, 2013, at 20:36, Konstantin Belousov <kostikbel@gmail.com> wrote:
> On Thu, Aug 15, 2013 at 08:13:34PM +0200, Dimitry Andric wrote:
>> Alternatively, we could attempt to figure out why gcc doesn't want to
>> inline those 64 bit builtins on FreeBSD.  It seems to have no problem
>> doing so on the first Linux box I tried...
> 
> Does the linux box defaults to pentium or higher for -march ?
> 64 bit atomics cannot be implemented in usermode on i386 on
> processors which do not have cmpxchg8b instruction.

Ah yes, you are totally right, with -v it gives:

  COLLECT_GCC_OPTIONS='-O2' '-S' '-v' '-mtune=generic' '-march=i586'

So we should really disable atomics for i486 and lower?  Though I have
understood that there also some pentiums without cmpxchg8b...




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