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Subject: Re: [OMPI devel] [PATCH] Open MPI on ARMv5
From: Leif Lindholm (Leif.Lindholm_at_[hidden])
Date: 2012-04-30 12:47:43


I'm happy for this to go in - Jeff?


> -----Original Message-----
> From: nave.notnilc_at_[hidden] [mailto:nave.notnilc_at_[hidden]] On Behalf
> Of Evan Clinton
> Sent: 30 April 2012 05:12
> To: Leif Lindholm
> Cc: Open MPI Developers; Jeffrey Squyres
> Subject: Re: [OMPI devel] [PATCH] Open MPI on ARMv5
> Thanks again for the comments.
> >> Quote the documentation, __kuser_cmpxchg "already includes memory
> >> barriers as needed," so the code using it shouldn't need anything
> >> extra.
> >
> > Fair enough - but could you put a comment to this effect into the
> patch?
> Comment added.
> > But I'm still not too happy about even the very unlikely risk of
> > something executing "random stuff" depending on kernel version.
> > For now, could you update the comments to that effect that:
> >
> > "These kernel functions are available on kernel versions 2.6.15 and
> > greater" + ", and running this software on earlier versions will
> result
> > in undefined behaviour."
> Comment added.
> > What I'm suggesting is not to parse information out of the build
> host,
> > but rather using the configured toolchain and options and try to
> > assemble the 64-bit atomic instructions. This would make it easy to
> > rebuild a generic ARMv6 package to support 64-bit atomics by just
> adding
> > -march=armv6zk to CFLAGS.
> Ah, I get it. I may see if I can come up with a nice test in the near
> future.
> For now, revised patch attached.

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