Re: RT Linux OS / Kernel which works with Comedi

On Thu, Sep 20, 2007 at 04:05:30PM -0400, Matthew Recchia wrote:
> Hi.  We have several applications that were written to run in FSM 
> Labs RT Linux Free.  There seems to be little support for this OS - 
> our new hardware isn't supported under the 2.4.x kernel.  Are there 

I have the same problem. RTLinux-3.2-gpl comes with comedi-0.7.65 and
linux-2.4, but my ni_pcimio 6221_37pin card only works with recent
comedi versions which are for linux-2.6 only.

> any suggestions regarding an OS that provides hard realtime support 
> and shouldn't require a total rewrite of the code (RTAI? Preempt-RT? 

AFAIK it should be possible to switch from linux-2.4-RTL to
linux-2.6-RTAI but this depends on your application code. I think there
are several people at rtai.org who use comedi in RT.

In my project I have very strict timing requirements. Furthermore I need
to use R.E.D.D. (RT Ethernet Device Drivers) which are available for
linux-2.4.x-RTL-3.2-gpl only. So I started porting comedi-2007-05-30 to
work with recent 2.4 kernels.

In my situation I only need to use comedi's low-level driver
functionalities because all my processing is done in kernel-space.
Therefore I removed most of the comedi device driver code
(comedi_fops.c). Instead of using comedilib and the chrdev, I call the
low-level functions directly. This way it was easy to use recent comedi
versions in linux-2.4 because most of the 2.6 related stuff is in
comedi_fops.c.

But keep in mind that the situation will get worse. If you need
long-term comedi support you must switch to linux-2.6 and cannot
use my approach.

> Ubuntu LinuxRT?)?  I wouldn't be the programmer doing the work - I'm 
> a systems integrator looking for advise regarding the OS with the 
> best prospects for support for I386 based PC's & PC-104 based 
> embedded controllers.  Thanks in advance for any suggestions / ideas 
> you may provide.

as stated above, this depends on your application code and your timing
requirements. long-term comedi support only with linux-2.6, i hope ;-)

-- georg

Received on 2007-09-21Z08:47:34