System reset during kernel debug

[mingming]

Using MP135F-DK board.

Setup the environment and rebuild kernel.

After I use openocd and gdb success connect to linux system, try to debug linux kernel, then run some simple gdb command like "bt" or do nothing, then system get reset.

I did not get much useful info from console (minicom).

if I don't pause system and let gdb "continue", then no reset.

Is it because watchdog ? how to disable it.

[PatrickF]

Hi @mingming ,

yes, it is likely a watchdog. Once started, you cannot disabled it, but you could decide to froze it when Cortex-A7 is stopped by debugger.

Please have a look to DBGMCU_APB4FZ.IWDG2

or DBGMCU_APB5FZ.IWDG1

Regards.

[mingming]

Hello Patrick,

Do you mean I should write IWDG1 and IWDG2 register when I pause CPU by GDB ?

Is there a way I can disable watchdog permanently.
like jumper?

Or bootloader configureation to disable it at boot time?

Regards.

[PatrickF]

Hi,

I mean you should try to use debugger to write in the DBGMCU registers I mention in order to setup HW to freeze watchdogs during debug phases.

 

Otherwise, watchdog could be permanently disabled (i.e not started) in the device tree:

https://wiki.st.com/stm32mpu/wiki/Watchdog_overview#Kernel_configuration
https://wiki.st.com/stm32mpu/wiki/IWDG_device_tree_configuration#DT_configuration_-28board_level-29

 

Regards.