Re: Orocos and RTAI/LXRT

Herman Bruyninckx wrote:
> On Wed, 25 Jun 2003, Pierangelo Masarati wrote:
> 
> [...]
> 
>>>Do you have more information on this topic you mention, i.e.,
>>>the programming policy to ensure no system calls are performed?
>>
>>any time a program in hard real-time executes a system call,
>>the process is kicked back to soft real-time.  All system calls
>>must be done thru LXRT calls.  This is basically
>>a trial-and-error process when adding real-time capabilities
>>to an existing program.  
> 
> 
> How can a not too experienced user be guided in this trial-and-error?
> How must she interpret the result of her trial-and-error, i.e., when
> does she see when something is (not) done appropriately?

I vaguely recall the possibility of switching on
some RTAI debugging that will log what system call
was invoked, and approximately where, when the
process was switched back to soft real-time.

When I say trial-and-error I mean you may want
to wipe out only the system calls that affect
your real-time process.  For instance, I didn't
care to use a mailbox for "can't solve this
problem; bye bye" messages.  You can also be
much more systematic and don't use system calls
at all, except for RTAI/LXRT replacements.

> 
> [...]
> 
>>I'm not aware of specific documentation on this, there has been
>>a flourishing of howtos and informal documents on RTAI and LXRT.
> 
> 
> Which boils down to no real documentation at all, in practice :-(


I'm not the right person to answer this question.
There is "official" documentation, but I'm not
sure it covers these points.  You should really
wait for Paolo to be back from his classroom :)

Pierangelo

-- 
Dr. Pierangelo Masarati               | voice: +39 02 2399 8309
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