rtems: Add RTEMS_INTERRUPT_REPLACE

A new option RTEMS_INTERRUPT_REPLACE is introduced that permits updating
the first interrupt handler for the registered interrupt vector and
matching argument.  If no match is found, the install function fails
with RTEMS_UNSATISFIED.

The Interrupt Manager Extension offers interrupt handlers with an
argument pointer.  It is impossible to update two words (handler and
argument) atomically on most architectures.  In order to avoid an SMP
lock in bsp_interrupt_handler_dispatch() which would degrade the
interrupt response time an alternative must be provided that makes it
possible to tear-down interrupt sources without an SMP lock.

Add RTEMS_INTERRUPT_REPLACE option to Interrupt Manager Extension.  This
enables a clean tear-down of interrupt sources on SMP configurations.
Instead of an interrupt handler removal a replacement handler can be
installed to silence an interrupt source.  This can be used in contexts
that allow no sophisticated synchronization (e.g. in atexit() or fatal
handlers).

0 files changed, 0 insertions, 0 deletions