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Subject: Re: building i386 world on amd64 host: failed @svn
From: Dimitry Andric <dim@FreeBSD.org>
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Date: Thu, 15 Aug 2013 21:12:52 +0200
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To: Konstantin Belousov <kostikbel@gmail.com>
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 Dmitry Morozovsky <marck@rinet.ru>, Peter Wemm <peter@wemm.org>
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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...