Re: [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg_double

[H. Peter Anvin]

On 12/24/2010 08:53 PM, Christoph Lameter wrote:
> On Thu, 23 Dec 2010, H. Peter Anvin wrote:
> 
>> There are two return registers; two machine registers can be returned in
>> registers.  [u]int128 is poorly implemented in a lot of gcc versions,
>> since it really hasn't been exercised.  However, two-word structures
>> should work.  I do not believe a two-word *array* works, though.
> 
> Oh gosh. So we would be using a tight corner case for gcc that may only
> work with certain versions of gcc? Note that the current version does only
> return a boolean. There is no need for returning double words. I'd be
> happy if we could *pass* double words.
> 


A structure is not a corner case; a uint128 would be.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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