The blog seems to offer only protection against writes to the NULL pointer (by designating the Flash ROM as a read-only MPU region). But how about reads from the NULL pointer?
I understand that the read protection is tricky because the vector table starts at address 0x0. So, how about relocating the vector table? Is that a part of the solution? I’d really like to see a working setup to effectively catch reads from the NULL pointer and some small offsets from NULL.