Re: [OT] Re: Teaching new tricks to an old dog (C++ -->Ada)

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Ed Falis writes:
> Ludovic Brenta writes:
>> That's what an unhandled exception results in.  In avionics, where
>> we have no operating system and no run-time system, exceptions
>> cannot propagate and thus always result in program termination.
>> When testing the program, we prove that no exception is ever
>> raised.
>
>
> There are certainly other strategies available.  For instance, in an
> "integrated modular avionics" architecture, an unhandled Ada
> exception in a single partition could be forwarded to a global
> health monitoring facility that may restart that partition, a set of
> partitions, or the whole system - or do something else for error
> recovery.  This implies that exception propagation is a quite
> flexible capability, and can be embedded in a system with even
> greater error handling flexibility in a comfortable way.

The software I'm currently working on is the "boot", or "BIOS" of our
hardware.  It allows us to upload an operating system onto the target
board.  The OS is then responsible for the partitioning that you
describe.  So, inside the "boot" software, we have absolutely nothing
we can use to propagate exceptions.  Every exception results in some
processor registers being set and a "jump" instruction to a fixed
address.  We can use the processor registers to easily find the point
where the exception was raised, but we cannot handle it.

In another project I worked on, there was only one partition, and
every exception would result in the watchdog restarting the software.

The mechanism you describe is indeed one possible solution for
software that runs on top of an operating system.

-- 
Ludovic Brenta.