Hard facts:
MCU: LCP54608j512
Custom hardware
Official LWIP Port from SDK 2.6.0.
FreeRTOS-MPU (Arm cortex M4 port for FreeRTOS)
Scenario:
Our hardware is running, while a tcp connection is being established.
In the field, i.e. 10 devices are running and communicating with a server.
This results in a memory management fault once in about 1-2 days on each device.
We were able to force this error with ping traffic adding to the already established tcp connection.
Failure:
Inside the ENET ISR, we are sporadically getting MemMange faults on code, which normally works fine. The fault occurs during access on privileged memory inside FreeRTOS API. However, our assumption was that memory access in ISRs always uses the default memory map and cannot cause a MemManage exception.
To exclude that unprivileged access via the MPU is taking place, we have raise the privilege using the corresponding FreeRTOS functions around the FreeRTOS API causing the fault.
We're currently stuck and out of approaches to further debug the issue.
Below you find the stack trace.
