[jmm-dev] [concurrency-interest] Will the real memory read barrier please stand up?

[Peter Sewell]

On 24 November 2014 at 00:09, Doug Lea <dl at cs.oswego.edu> wrote:
> On 11/20/2014 05:25 AM, Andrew Haley wrote:
>>
>> On 20/11/14 10:12, Joe Bowbeer wrote:
>>>
>>> As far as I can tell, the cookbook hasn't been updated yet for ARMv8.
>
>
> Mainly out of conservatism given the history of revising ARM and POWER
> entries multiple times over the years, sometimes based on incomplete or
> wrong information. It seems worth waiting for multiple validations,
> including experience from the ARMv8 hotspot port. This is cruel to Andrew
> (sorry!) but still better than alternatives.
>
>>> looks like the following might be helpful in updating the recipes.
>>>
>>> http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html
>>
>>
>> Yes, it looks like the DMB LD is now stronger if, that page is right.
>>
>> It'd be nice if someone could point me at the language in the
>> ARMv8 spec that this derives from.
>
>
> I'm hoping that someone from ARM answers this.

That table came from ARM, though not via the ARM ARM, so it certainly
matched their intent.    We are working on modelling the v8
primitives, but I couldn't say we have a definitive story (backed up
by extensive testing and model comparison)  yet.

Peter


> -Doug
>