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

[Sebastian Huber]

On 07.07.23 18:26, Martin Åberg wrote:
> 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?

Yes, exactly. The API to customize the fatal error handling for 
applications is the CONFIGURE_INITIAL_EXTENSIONS application 
configuration option. There is absolutely no need for a BSP-specific 
solution.

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