Re: [boost] [atomic] unconditional cmpxchg8b support

Subject: Re: [boost] [atomic] unconditional cmpxchg8b support
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2012-10-23 07:41:39

On 23/10/12 11:40, Tim Blechmann wrote:
> hi helge & list,
>
> using boost.atomic on ia32/gcc causes me quite some headaches these
> days, as the cmpxchg8b instruction is enabled via the __i686__ or
> __x86_64__ macros.
> however on debian for example, the compiler defaults to generate code
> for i486. cmpxchg8b has been introduced with the p5 architecture,
> though, so compiling without specifying a -march flag won't generate the
> instruction.

GCC will not let you use instructions outside of the target architecture.

This is normal and expected behaviour.