Re: Update on shared memory coarrays

["Nicolas König" <koenigni@student.ethz.ch>]

Hello Iain,

On 02/01/2021 21:55, Iain Sandoe wrote:
> Thomas Koenig via Fortran <fortran@gcc.gnu.org> wrote:
> 
>>> map_memory image 0 size 1000 offset 0 pagesize 1000
>>> map_memory image 0 size 2000 offset 0 pagesize 1000
> 
> pagesize 1000?

Pretty sure that's hex :)

> 
> Darwin’s pagesize is 4096 for PPC/X86 and 16384 for Arm64(aarch64).
> 
>>> mmap failed: Invalid argument
>>
>> That means that a rewrite of shared_memory.c and shared_memory.h
>> is required.
>>
>> I checked the attached program on every Unixoid system I
>> could lay my hands on (Linux, AIX, OpenBSD, NetBSD, FreeBSD,
>> OpenSolaris), and it passed everywhere.  Seems like MacOS
>> is the only one where this particular idiom does not work.
> 
> Perhaps I’m missing what the idiom is here :)

At the moment, we are double-mapping pages in the shared_memory. This 
was on the list of things that should be changed, but according to 
Thomas's tests, you can't do this on MacOS, so it just got a whole lot 
more important.

   Nicolas

> 
> (a bit tied up with other things at the moment so mainly watching from
>   the peanut gallery for now)
> 
> Iain
>