Re: cmpxchg and x86 flags output

From: H. Peter Anvin
Date: Fri Aug 19 2016 - 13:25:16 EST


On 06/22/16 09:14, David Howells wrote:
> H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
>> So how do we make this move forward?
>
> Getting my API additions in is relatively straightforward, I think. The
> whether-or-notness of the cmpxchg operation succeeding can be calculated by
> comparing the original value read from memory with the value-to-be-replaced
> inside the API function.
>
> This can later be replaced with the boolean output from the CMPXCHG
> instruction, the branch target from the LL/SC skipping or the result of the
> intrinsics.
>

Hi David,

Any news on this? Can we perhaps help making this go forward at some point?

-hpa