[PATCH] Linux: Implement membarrier function

[Florian Weimer]

* Torvald Riegel:

> On Wed, 2018-11-28 at 16:05 +0100, Florian Weimer wrote:
>> This is essentially a repost of last year's patch, rebased to the glibc
>> 2.29 symbol version and reflecting the introduction of
>> MEMBARRIER_CMD_GLOBAL.
>> 
>> I'm not including any changes to manual/ here because the set of
>> supported operations is evolving rapidly, we could not get consensus for
>> the language I proposed the last time, and I do not want to contribute
>> to the manual for the time being.
>
> Fair enough.  Nonetheless, can you summarize how far you're along with
> properly defining the semantics (eg, based on the C/C++ memory model)?

I wrote down what you could, but no one liked it.

<https://sourceware.org/ml/libc-alpha/2017-12/msg00796.html>

I expect that a formalization would interact in non-trivial ways with
any potential formalization of usable relaxed memory order semantics,
and I'm not sure if anyone knows how to do the latter today.

Thanks,
Florian