Problem calling POSIX libc functions on espressif boards

[OgnjenX]

When I try to call rand() or (I believe) any other POSIX function from C standard library on 'esp32_devkitc_wroom' target, program causes halting, like this:

*** Booting Zephyr OS build zephyr-v3.5.0-2845-g7b78393b07a6 ***
[00:00:01.511,000] <err> os:  ** FATAL EXCEPTION
[00:00:01.511,000] <err> os:  ** CPU 0 EXCCAUSE 28 (load prohibited)
[00:00:01.518,000] <err> os:  **  PC 0x4000be94 VADDR 0
[00:00:01.524,000] <err> os:  **  PS 0x60e20
[00:00:01.529,000] <err> os:  **    (INTLEVEL:0 EXCM: 0 UM:1 RING:0 WOE:1 OWB:14 CALLINC:2)
[00:00:01.538,000] <err> os:  **  A0 0x8000105e  SP 0x3ffe6b80  A2 0x60e20  A3 0x3ffb26f8
[00:00:01.547,000] <err> os:  **  A4 0x3ffe6b80  A5 0x4  A6 0x3ffe6b90  A7 0
[00:00:01.554,000] <err> os:  **  A8 0  A9 0x3ffe6b50 A10 0xfffffff5 A11 0x3ffb26f8
[00:00:01.563,000] <err> os:  ** A12 0x3ffb26f8 A13 0x4 A14 0x3ffb24f8 A15 0xffffffff
[00:00:01.571,000] <err> os:  ** LBEG 0x4000c46c LEND 0x4000c477 LCOUNT 0
[00:00:01.579,000] <err> os:  ** SAR 0x10


Backtrace:0x4000be91:0x3ffe6b80 0x4000105b:0x3ffe6ba0 0x400d06b6:0x3ffe6bc0 0x4008182b:0x3ffe6be0 0x400d0eb3:0x3ffe6c00 
0x400d06b6: main at /home/ognjen/Robbit/StartUp/micRobbit/zephyr-firmware/microbbit-zephyr-workspace/micRobbit-firmware/app/src/main.cpp:36

0x4008182b: bg_thread_main at /home/ognjen/Robbit/StartUp/micRobbit/zephyr-firmware/microbbit-zephyr-workspace/zephyr/kernel/init.c:371

0x400d0eb3: z_thread_entry at /home/ognjen/Robbit/StartUp/micRobbit/zephyr-firmware/microbbit-zephyr-workspace/zephyr/lib/os/thread_entry.c:48


[00:00:01.595,000] <err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
[00:00:01.603,000] <err> os: Current thread: 0x3ffb26f8 (unknown)
[00:00:01.609,000] <err> os: Halting system

That log is concretely produced by this small program:

#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <cstdlib>

LOG_MODULE_REGISTER(main, CONFIG_APP_LOG_LEVEL);

int main(void)
{
	auto rand_num = rand();
	printk("Random number %d\n", rand_num);
	// Nothing to do here for now
}

Does anyone know something about this? Are there some known limitations in the current espressif toolchain in Zephyr?
(motivation for opening this issue can be found here micro-ROS/micro_ros_zephyr_module#131 (comment))

Thanks in advance!

[github-actions]

Hi @OgnjenX! We appreciate you submitting your first issue for our open-source project. 🌟

Even though I'm a bot, I can assure you that the whole community is genuinely grateful for your time and effort. 🤖💙

[sylvioalves]

@OgnjenX Hi, same is happening with a few other functions. I am checking this. Thanks.