Re: [Xenomai-help] trap exceptions in user

[Gabriele Moabiti <gabmoa@domain.hid>]

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>I think you are traping yourself with impossible constraints.
>
>Anyway, the only way is register a custom exception handler using rthal
>functions. In your trap handler, you may wake up a user-space server
>thread which role is to handle exceptions (in user-space). This means that:
>- upon exception, you have a switch to the user-space server thread
>context, this will be slow;

Do I change rthal inside xenomai? How can I do?
Is there a benchmark or some number to understand better this slowness (in us)?

>- you have to rewrite the exception handling code, you can not rely
>on the exception handling code that was written in the assembly blob.
>
>I do not think it is a good idea to simply override the exception
>vectors, the kernel uses them, and you certainly want the kernel to
>continue working.
 
Yes I think so

Now SIS is about 500 kb of pure asm and works with a big cli on start and a sti
on finish @ring 0 and reprogram the exception vectors but I want to integrate into xenomai. 

Proposal:

- At start SIS save the addresses of the exception vectors
- When an exception is raised then the processor switch to the custom exception vectors but
  if the SIS is not currently active then jump to the old exception vectors

Is it possible?

Sorry for the large number of questions


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