When using MPU wrappers version 2 (configUSE_MPU_WRAPPERS_V1 == 0),
portRAISE_PRIVILEGE() is a no-op because the portSVC_RAISE_PRIVILEGE
handler is compiled only for MPU wrappers version 1. As a result, an
unprivileged task that calls taskENTER_CRITICAL() does not actually raise
its privilege, so the subsequent BASEPRI write is ignored by the hardware
and the critical section silently fails to mask interrupts. This produces
latent, hard-to-debug faults.
configALLOW_UNPRIVILEGED_CRITICAL_SECTIONS is therefore not supported with
MPU wrappers version 2. In the ARMv7-M MPU ports:
- When the option is left undefined under v2, default it to 0 instead of 1
so the dangerous default configuration is safe.
- When the option is explicitly set to 1 under v2, raise a compile-time
#error so the unsupported configuration is rejected loudly rather than
failing silently at run time.
Behaviour for MPU wrappers version 1 is unchanged.
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