Re: [PATCH] kern: simple futex for gnumach (version 4)

[Marin Ramesa]

On 12/24/2013 03:25:15 PM, Richard Braun wrote:
> > There is a one call to vm_map lookup to retrive the offset and the
> > object. Simple
>
> How do you implement cross address space synchronization ?

I use a recursive futex_wake(). It first scans all the futexes if
they are on the same offset and if they share the same vm_object.
If they do, recursion is used to wake a number of threads in those
futexes. The number of threads awakened is constant troughout the
same offsets and in the same objects. In this way synchronization
is possible. I don't do anything in futex_wait().