RE: Mutexes on L4Ka::Pistachio?

Hi Farid,

> On OKL4, there's a kernel-supported mutex_t object in their lib, but I see
> nothing similar in L4Ka::Pistachio; neither in the spec, nor in the source of
> kernel and user.
You're right, pistachio doesn't offer a kernel-supported mutex/locking scheme at the moment.

> If the kernel doesn't provide mutexes, they have to be implemented in user
> space, right? I'm thinking of something like a dedicated 'mutex' manager
> thread per task, that other threads would [L]IPC to lock and unlock mutexes.
> Does that make sense, or am I completely lost here?
Sounds sensible. But I'm also sure OKL4 has a reason to offer a kernel primitive. My guess is that it is because kernel notifications are convenient and can be better integrated into the scheduler and/or other kernel subsystems. But I personally have never looked into the details, so it might make sense to ask the OKL4 developers directly.

Best,
-Jan

--
Dr.-Ing. Jan Stoess
KIT/UKa System Architecture Group
Phone: +49 (721) 608 4056
Fax: +49 (721) 608 7664
http://os.ibds.kit.edu/stoess