[PATCH v1 1/3] cpukit: Add signal mapping support

[Chris Johns]

On 20/4/21 3:54 pm, Sebastian Huber wrote:
> On 20/04/2021 07:30, Chris Johns wrote:
> 
>> We need a way for libdebugger or any other piece of software to capture and
>> cascade the call. If this can be done on aarch64 then I am happy.
> 
> The fatal error extensions execute in a user controllable order. You can for
> example register a libdebugger handler which deals with break point exceptions
> before the signal mapping handler is called.
> 
> Synchronous exceptions should end up in an RTEMS_FATAL_SOURCE_EXCEPTION fatal
> error. The fatal code is a pointer to rtems_exception_frame
> (CPU_Exception_frame). In this data structure should be the complete state of
> the interrupted context (which could be also an interrupt handler). If you want
> to resume execution of the interrupted context, then we need an API for this
> (setters/getters and some sort of a longjmp()).

I do not think the fatal error handler support is suitable for a debugger, the
frame maybe on the wrong stack. It was more complicated to implement than this
and the reality of what is needed on the ARM required lots more. The fatal error
handler handles fatal errors however surviving a data abort and then continuing
in the correct CPU context/space and stack is much harder to do ....

https://git.rtems.org/rtems/tree/cpukit/libdebugger/rtems-debugger-arm.c#n1454

That code has to work with all data and states saved.

Chris