Question
chip enters NMI handler with debugger attached
I am having issues debugging a STM32H7 series chip (STM32H755).
When I connect using multiarch-gdb and run `mon swdp_scan` it crashes both cores. I am using a BMP debugger. I end up in the NMI handler. I can see via the external LEDs in the code that it is the monitor command which is causing the interrupt.
(gdb) tar ext /dev/ttyACM0
Remote debugging using /dev/ttyACM0
(gdb) monitor swdp_scan
Target voltage: 3.3V
Available Targets:
No. Att Driver
1 STM32H7 M7
2 STM32H7 M4
(gdb) attach 1
Attaching to program: /CM7/jc_m7_cube.elf, Remote target
NMI_Handler () at /CubeMX/CM7/Core/Src/stm32h7xx_it.c:77
77 while (1)
(gdb) list *$pc
0x80009d4 is in NMI_Handler (CubeMX/CM7/Core/Src/stm32h7xx_it.c:77).
72 /* USER CODE BEGIN NonMaskableInt_IRQn 0 */
73
74 /* USER CODE END NonMaskableInt_IRQn 0 */
75 HAL_RCC_NMI_IRQHandler();
76 /* USER CODE BEGIN NonMaskableInt_IRQn 1 */
77 while (1)
78 {
79 }
80 /* USER CODE END NonMaskableInt_IRQn 1 */
81 }
(gdb) If I hard reset the microcontroller using the reset line, and then do the same steps as above, it will execute normally.
Why is this happening?