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Subject: Re: [OMPI devel] [PATCH] Open MPI on ARMv5
From: Jeffrey Squyres (jsquyres_at_[hidden])
Date: 2012-04-19 11:21:29


Thanks Evan!

(sorry for the delay in replying -- I was on vacation all last week and I'm *still* catching up...)

Lief -- does this look good to you?

On Apr 13, 2012, at 11:13 PM, Evan Clinton wrote:

> At present Open MPI only supports ARMv7 processors. Attached is a
> patch against current trunk (r26270) that extends the atomic
> operations and memory barriers code to work with ARMv5 and ARMv6 ones,
> too.
>
> For v6, the only changes were to use "mcr p15, 0, r0, c7, c10, 5"
> instead of the unavailable DMB instruction, and to disable the 64 bit
> compare-exchange function (which I understand is not vital for Open
> MPI on 32 bit platforms?). For v5, it was a bit trickier; the
> processor lacks nice memory barrier instructions or proper atomic
> operations. Fortunately, the Linux kernel offers several helper
> functions on ARM, and I've used those here.
>
> The changes build and pass all of the assembly-related tests in the
> test folder and the hello world examples run on my "armv5tel" box
> running Debian with Linux 2.6.32-5. It should also run fine on ARMv6
> boxes, and presumably v4, but I don't have either to test on.
>
> Documentation for the Linux kernel helper functions:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=Documentation/arm/kernel_user_helpers.txt
>
> I've sent in a contributor agreement so there should be no IP problems.
>
> Hopefully this is useful,
> Evan Clinton
> <ompi_armv5.diff>_______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel

-- 
Jeff Squyres
jsquyres_at_[hidden]
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