[PATCH v2 22/32] bsp/leon3: Simplify fatal error handling

[Martin Åberg]

Please see the comment below.

On 2023-07-05 13:18, Sebastian Huber wrote:
> ---
>   bsps/sparc/leon3/include/bsp/leon3.h | 12 ++++
>   bsps/sparc/leon3/start/bspclean.c    | 89 +++++++++++++++++++---------
>   bsps/sparc/leon3/start/bspsmp.c      | 16 +----
>   3 files changed, 77 insertions(+), 40 deletions(-)
> 

> @@ -92,7 +124,10 @@ void bsp_fatal_extension(
>   #endif
>   
>   #if BSP_RESET_BOARD_AT_EXIT
> -  /* If user wants to implement custom reset/reboot it can be done here */
> -  bsp_reset();
> +  /*
> +   * Stop the system termination right now.  This skips the dynamically
> +   * installed fatal error extensions and the generics shutdown procedure.
> +   */
> +  _CPU_Fatal_halt( source, code );
>   #endif
>   }


Some thoughts and questions on the implication of this.

As I understand it, bsp_reset() here was intended as a way for the user to
provide an application/mission specific way to take late action on a fatal
event. And also that bsp_reset() was called in a "single-processor 
state" where
the other processors had already been stopped (powered down).

Some potential use cases for action in a bsp_reset(), I can think of:
- Log an entry in an off-chip, on-board non-volatile memory with a record
   consisting of system date, fatal_source and fatal_code.
- Signal the event, using GPIO, to an external failure/redundancy 
controller.
- Tell an on-board reset circuit to initiate a board reset/shutdown.
- Issuing a "warm" system restart by jumping to a known location in a 
ROM boot
   loader.

The _CPU_Fatal_halt looks like a path of no return (error mode) and no more
user hooks. But would it perhaps be possibility for the application to 
provide
an extension with CONFIGURE_INITIAL_EXTENSIONS to have application specific
actions like the ones above?



-- 
Best regards,

Martin Åberg
Software Engineer
Frontgrade Gaisler
martin.aberg at gaisler.com

Frontgrade Gaisler AB, Kungsgatan 12, SE-411 19 GÖTEBORG, Sweden.
+46 (0) 31 775 8650, www.gaisler.com