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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