When I used armclang to compile the code of arm cm7, I found a surprising bug in armclang, which is manifested in the following assembly instructions generated under -O2/-Os/-Ofast/-O3/-Os/....:
__asm(
"ldr r5,=0x20010402"
);
"ldr r7,=0x55f4"
"strbt r7,[r5,#6]"
The CPU is in privileged mode all the time.when the CPU executes the STRBT instruction, it enters the memmanage_handler interrupt function.
Arm A-profile A32/T32 Instruction Set Architecture
solution: even in privileged mode, the MPU must be configured, as the machine instructions generated by the compiler may cause memmanage errors.
config all ram area: full access ,BUFFERABLE,CACHEABLE,SHAREABLE,LEVEL0
so I think it's a compiler bug.
armclang version:
.\armclang.exe -vProduct: MDK Professional 5.36Component: ARM Compiler 6.16Tool: armclang [5dfeb700]
Additional Notes:
CHIP：STM32H723ZGT6
KEIL：5.36
HostOS：win10