Newbie Question about userspace and how to use zephyr_library_app_memory correctly

[TianlongLiang]

Thank you for taking the time to look at my question. I'm new to this project and still learning, so I truly appreciate any guidance or help you can provide. If there's something I missed or could improve in my approach, please let me know—I'd be happy to learn and adjust.

Let's say I have a simple project structure like this:

• src
  • main.c
• lib-test
  • test.c
  • CMakeLists.txt
• CMakeLists.txt

In the root CMakeLists.txt I will have something like this:

cmake_minimum_required(VERSION 3.13.1)
find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

project(app LANGUAGES C)

add_subdirectory(lib-test)

target_link_libraries(app PRIVATE test_lib)

target_sources(app PRIVATE src/main.c)

And the CMAkeLists.txt for lib-test will be like:

# Define a new Zephyr library
zephyr_library_named (test_lib)

# Add source files to the library
zephyr_library_sources (
  test.c
)

# Specify the memory partition where all globals in the library should be placed.
zephyr_library_app_memory (test_partition)

My plan is to write the test.c like normal C source file would, don't have any Zephyr macro for memory partition for global variables:

#include <stdio.h>

// Define a global integer variable
int a = 1;

// Function to print "Hello, World!" and the value of the global variable a
void print_hello_world(void) {
    printf("Hello, World!\n");
    printf("The value of the global variable a is: %d\n", a);
}

And I define the test_partition in main.c:

#include <stdio.h>
#include <zephyr/app_memory/app_memdomain.h>

#define CONFIG_MAIN_THREAD_STACK_SIZE 8192

#define MAIN_THREAD_STACK_SIZE (CONFIG_MAIN_THREAD_STACK_SIZE)
#define MAIN_THREAD_PRIORITY 5

K_THREAD_STACK_DEFINE(user_mode_thread_stack, MAIN_THREAD_STACK_SIZE);
static struct k_thread user_mode_thread;

K_APPMEM_PARTITION_DEFINE(test_partition);

struct k_mem_domain test_domain;

void print_hello_world(void);

void
test_main(void *arg1, void *arg2, void *arg3){
    print_hello_world();
}

bool
test_user_mode(void)
{
    struct k_mem_partition *domain_parts[] = { &test_partition};

    /* Initialize the memory domain with single partition */
    k_mem_domain_init(&wamr_domain, 1, domain_parts);

    k_tid_t tid =
        k_thread_create(&user_mode_thread, user_mode_thread_stack,
                        MAIN_THREAD_STACK_SIZE, test_main, NULL, NULL, NULL,
                        MAIN_THREAD_PRIORITY, K_USER, K_FOREVER);

    k_mem_domain_add_thread(&test_domain, tid);
    k_thread_start(&tid);

    return tid ? true : false;
}

main(void)
{
    iwasm_user_mode();
    printk("Hello, world from main thread\n");
}

I can get the project to compile and run on the qemu-x86_32 board, but the user mode thread didn't run correctly and hung. My log indicates the fail on spinlock assertion:

ASSERTION FAIL [z_spin_lock_valid(l)] @ WEST_TOPDIR/zephyr/include/zephyr/spinlock.h:136
        Invalid spinlock 0x4011d5e8

Thank you in advance for your support!

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[TianlongLiang]

My prj.conf is as follow, nothing fancy:

CONFIG_USERSPACE=y
CONFIG_PRINTK=y
CONFIG_LOG=y
CONFIG_LOG_BUFFER_SIZE=4096

CONFIG_ASSERT=y