os: Illegal use of the EPSR-disco_l475_iot1

[mtahirbutt]

Describe the bug
When I run samples/net/updatehub app without internet connection, I see the error message on the console after some time (3, 5, 10 minutes etc.) and the program stops. The program stops usually even after probing the internet.

[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: ***** USAGE FAULT *****[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: Illegal use of the EPSR[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: r0/a1: 0x20001a68 r1/a2: 0x00000001 r2/a3: 0x00000000[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: r3/a4: 0x80000000 r12/ip: 0x00000000 r14/lr: 0x0802f2e1[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: xpsr: 0x80000000[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: Faulting instruction address (r15/pc): 0x00000000[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0[1B][0m
[1B][8D[1B][J[00:09:51.018,000] [1B][1;31m os: Current thread: 0x2000116c (unknown)[1B][0m
[1B][8D[1B][J[00:09:51.095,000] [1B][1;31m os: Halting system[1B][0m

A clear and concise description of what the bug is.
What have you tried to diagnose or workaround this issue?

I tried to increase stack sizees etc.

CONFIG_INIT_STACKS=y
CONFIG_THREAD_STACK_INFO=y
CONFIG_HEAP_MEM_POOL_SIZE=8192
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=8192

I also saw the issues (i2c: frdm-k64f and mimxrt1050_evk I2C driver will cause hardware exception if read/write to a not existing device #12849). but no idea how that links to this problem.

thought may be due to low memory allocation. but no workaround yet.
I also followed this link https://lists.zephyrproject.org/g/users/topic/random_fault_exception/30793151
and tried -DCONFIG_NO_OPTIMIZATIONS=y.

but resulted in

[1B][1;32muart:~$ [1B][m[1B][1B[1B][9D[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: ***** USAGE FAULT *****[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: Illegal use of the EPSR[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: r0/a1: 0x00000000 r1/a2: 0x0000e4c7 r2/a3: 0x00000000[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: r3/a4: 0x20007680 r12/ip: 0x00000006 r14/lr: 0x00000000[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: xpsr: 0x0802ea00[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: Faulting instruction address (r15/pc): 0x200076a0[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0[1B][0m
[1B][8D[1B][J[00:00:00.547,000] [1B][1;31m os: Current thread: 0x20002f34 (unknown)[1B][0m
[1B][8D[1B][J[00:00:00.609,000] [1B][1;31m os: Halting system[1B][0m

To Reproduce
Steps to reproduce the behavior:

1. mkdir build; cd build
2. cmake -DBOARD=disco_l475_iot1
3. make
4. See error

Expected behavior
A clear and concise description of what you expected to happen.

I do not understand where this is coming from may be because of network socket, I do not see this problem with other apps which I tried from zephyr. may be mcuboot has some issue. I also tried blinking led app with mcuboot i do not see the problme there.

Impact
What impact does this issue have on your progress (e.g., annoyance, showstopper)

I am not able to progress to next step.

Screenshots or console output
If applicable, add a screenshot (drag-and-drop an image), or console logs
(cut-and-paste text and put a code fence (```) before and after, to help
explain the issue.

Environment (please complete the following information):

• OS: (e.g. Ubuntu)
• Toolchain (e.g Zephyr 2.2.0, SDK 0.11.2 ...)
• Commit SHA or Version used

Additional context
Add any other context about the problem here.

[mtahirbutt]

Hi the issues is resolved with removing DNS servers options in the config file.