Allowed system calls in ISRs

Joel Sherrill <> joel.sherrill at
Fri May 27 13:23:01 UTC 2005

Ingolf Steinbach wrote:
> Hi,
> section 6.3 of the RTEMS C users' guide lists system calls that
> may be made from ISRs. Apparently this list is incomplete:
> "Interrupt Manager" is missing completely while section 6.4.5
> suggests that at least rtems_interrupt_is_in_progress() is
> allowed in ISRs.
> I'm specifically interested in rtems_interrupt_catch(): is
> it allowed to change an interrupt handler while in an ISR?

That should be OK.  It doesn't allocate memory or block.  Those
are the two biggest factors.

> Kind regards
>     Ingolf

Joel Sherrill, Ph.D.             Director of Research & Development
joel at                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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