Debugging nRF5340 Net CPU Causes Stack Overflow on Reset

RE: Debugging nRF5340 Net CPU Causes Stack Overflow on Reset

anthony32086 — Wed, 16 Jun 2021 12:39:40 GMT

Setting CONFIG_INIT_ARCH_HW_AT_BOOT does indeed fix the problem with no other changes to the base reset.S.

The only time I observe this issue is when debugging so you mentioning that the debugger should perform a reset but not doing it makes sense. Cold boots with no debugger attached do not observe any hardfaults.

The debugger I am using is a JTrace attached externally to P18 (debug in) on the devboard however I can confirm that it the issue was also present when using the built in JLink.

RE: Debugging nRF5340 Net CPU Causes Stack Overflow on Reset

Sigurd — Wed, 16 Jun 2021 11:58:11 GMT

Hi,

The Network core is a regular Cortex-M33 and any warm/cold reset should be initializing the CONTROL register. If the debugger does not do it on the NET core, then this might be a problem.

One thing that you can do is to set the CONFIG_INIT_ARCH_HW_AT_BOOT Kconfig option for the network core. This option will set the CONTROL register before anything else, in reset.S:

#if defined(CONFIG_INIT_ARCH_HW_AT_BOOT)
    / Reset CONTROL register /
    movs.n r0, #0
    msr CONTROL, r0
    isb
#if defined(CONFIG_CPU_CORTEX_M_HAS_SPLIM)
    / Clear SPLIM registers /
    movs.n r0, #0
    msr MSPLIM, r0
    msr PSPLIM, r0
#endif / CONFIG_CPU_CORTEX_M_HAS_SPLIM /

This will ensure that the MSP is used at Network core boot, and not the PSP.

Let me know if this workaround works for you or not.

RE: Debugging nRF5340 Net CPU Causes Stack Overflow on Reset

Sigurd — Tue, 01 Jun 2021 12:18:47 GMT

Hi,

Thank you for reporting this. I have reported this internally. I will keep you posted about our findings.