[PATCH] score/arm: make MPU setup more generic

[Karel Gardas]

On 3/16/23 10:19, Sebastian Huber wrote:
> On 16.03.23 10:14, Karel Gardas wrote:
>> This patch makes MPU setup more generic by adding capability to set
>> also control register. This way BSPs are allowed to enable MPU
>> also for hard faults by simply not setting PRIVDEFENA attribute
>> to control register. Compatibility with previous behavior and API
>> is preserved.
> 
> Is this really a BSP-specific choice or more a user option which should 
> be controlled by a BSP option (through config.ini)?

config.ini would be even more generic and probably more elegant too. 
However for upstreaming I took a more conservative approach to have a 
chance.

Let me ask what do you prefer and what will you support? I'm happy to 
write that as long as it is reasonable simple and makes chance to 
upstream higher.

My goal is simple:
I'm working on BSP for Precidata SL-3011 board. The board is using 
STM32H747. Board firmware responsible for hardware management runs on 
CM4 while RTEMS and app code will run on CM7 and will be using firmware 
services by calling some API. For communication between both domains we 
use SRAM4. To be able to print hard fault from RTEMS on CM7 I need either:

- keep cache disabled for SRAM4 region even for hard fault (hence MPU 
change proposed)

or

- disable cache in print exception frame directly which involves quite a 
bit of hacking around and looks to be more source code invasive than MPU 
change.

Thanks!
Karel