What is the behavior after configuring the background MPU in Cubemx?

[zzzaizz]

The development board I am using is stm32h723. Assuming I only configured region 0 and wrote a blacklist, all regions (both privileged and non-privileged) are inaccessible. The remaining 15 regions were not configured. However, in the MPU Control Mode, I configured "Background Region Privileged access only + MPU Disable during hard fault, NMI and FAULTMASK handlers". This means that for unconfigured regions, only the privileged can access them, and the MPU is disabled during hard faults, NMI, and FAULTMASK handlers. What would happen after this configuration? The CPU is in bare-metal mode without an operating system, and it is in privileged mode. Who should it listen to?

[mƎALLEm · Accepted solution]

Hello,

The explanation of that MPU background region is provided in this post: Information about MPU settings for the STM32H743

That background configuration impacts only the external memories and unused memory regions to prevent any CM7 speculative access to invalid memory regions.