All kernel processes run in the same address space but not every "global"
data object in each module is accessible every other module, only the ones
that the module chooses to use with EXPORT_SYMBOL to make it available to
the kernel. If you do this then you can always create the semaphore in the
first module to be loaded and have it accessible to every other module you
write.
Norm
> -----Original Message-----
> From: Thamm, Russell [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, October 24, 2001 1:14 AM
> To: '[EMAIL PROTECTED]'
> Subject: RE: [rtl] Named Semaphores
>
> All the semaphore functions supported by RTLinux are for unnamed
> semaphores.
> Posix also defines functions for named semaphores eg sem_open.
>
> Process A needs to communicate with process B using a semaphore.
> Process A opens a semaphore named "Jack". Process B opens a named
> semaphore named "Jack", voila both processes have a handle to the
> SAME semaphore.
>
> How do you achieve this with unnamed semaphores?
>
> However, it does occur to me that all rtl modules might run in the same
> process
> space in which case the question is academic.
>
> I have been using RTX realtime extensions for NT and I am probably making
> some
> inaccurate assumptions about RTLinux based on my RTX experience. All RTX
> IPC
> mechanisms are named (shared memory, events, semaphores, mutexes etc) and
> all RTX programs are separate processes.
>
>
> Russell Thamm
>
> -----Original Message-----
> From: Ish Rattan [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, October 23, 2001 10:49 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [rtl] Named Semaphores
>
>
> On Tue, 23 Oct 2001, Thamm, Russell wrote:
>
> > Hi,
> >
> > I want to use semaphores for communication between 2 realtime processes.
> >
> > The obvious choice is to use named semaphores but RtLinux doesn't seem
> to
> Semaphore by definition uses shared varibale synchronization technique.
> So, what is a named semaphore?
>
> -ishwar
>
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