[Xenomai-help] Shared Memory?

[Xenomai-help] Shared Memory?

[Kent Borg]

Looking at the Xenomai documentation, I can't see how to do shared
memory communication between a realtime and non-realtime userland
task.  Do I just use regular Linux shared memory, but somehow lock it
down?

Thanks,

-kb

Re: [Xenomai-help] Shared Memory?

[Jan Kiszka]

[-- Attachment #1: Type: text/plain, Size: 563 bytes --]

Kent Borg wrote:
> Looking at the Xenomai documentation, I can't see how to do shared
> memory communication between a realtime and non-realtime userland
> task.  Do I just use regular Linux shared memory, but somehow lock it
> down?
> 

Use mixed RT/non-RT threads and you will have shared mem for free, use
processes and you only have to ask linux for some shared fragments. In
any case don't forget to mlockall() your RT-processes!

Jan


PS: You only need "special" Xenomai services for allocating mem when you
want to shared it between kernel and user land.

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 256 bytes --]

Re: [Xenomai-help] Shared Memory?

[Kent Borg]

On Wed, Dec 21, 2005 at 12:48:17AM +0100, Jan Kiszka wrote:
> Use mixed RT/non-RT threads and you will have shared mem for free, use
> processes and you only have to ask linux for some shared fragments. In
> any case don't forget to mlockall() your RT-processes!

So does that mean regular shmget() to set up the shared memory, and
mlockall() in the RT process?  I was thinking mlock(), but you have a
point that mlockall() would be better!

I haven't done shared memroy before, but it looks pretty easy.


Thanks,

-kb