Fw: [realtime] Hard real time in user space.


Thread Starter

Phil Covington

----- Original Message -----
From: "Paolo Mantegazza" <[email protected]>
To: <[email protected]>
Sent: Monday, January 31, 2000 12:40 PM
Subject: [realtime] Hard real time in user space.

> Hi,
> At http://www.aero.polimi.it/projects/rtai/, and soon at related
> mirrors, you can find rtai-x.xa.tgz (the x.x stands for experimental).
> It is the first release of a new extension to the RTAI-LXRT development
> thread aimed at allowing you to do hard real time in user space.
> Once more it is done in the RTAI spirit of not touching the kernel. Just
> 4 lines of code added/modified with respect to the usual RTAI changes,
> and the kernel becomes premptable.
> It is still in its infancy but the idea seems to work. You pay some
> overhead compared to doing it in kernel space but the latency seems
> good. Check it yourself.
> Now you can implement real time tasks using three approaches:
> - Hard real time kernel modules (as before).
> - Hard real time user space programs (a somewhat constrained Linux
> process doing hard real time under lxrt).
> - Soft real time Linux process (real time Linux processes under lxrt).
> All the above using the complete RTAI API: within the kernel, within
> user space, or between the two.
> You can start with a plain process, improve it to real time in user
> space and then go to the kernel if needed. Further developement will
> allow debugging real time tasks in user space under the protection of
> the MMU.
> This extension of the existing LXRT module is the result of the joint
> development effort of:
> - Pierre Cloutier
> - Lorenzo Dozio
> - Paolo Mantegazza
> - Steve Papacharalambous.
> Any comment, bug report and help is welcomed.
> Ciao, Paolo.
> P.S. Official RTAI latest is 1.0. It containes lxrt-informed, a great
> contribution for user space applications, from Pierre Cloutier, and
> improved POSIX APIs, with message queues, from Trevor Woolven.

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