Modules and Apps¶

Develop kernel modules and userspace applications with ELMOS.

Kernel Modules¶

Create Module¶

./build/elmos module create <name>

Generates template in examples/modules/<name>/ with Makefile and <name>.c.

Build Module¶

cd examples/modules/<name>
make  # Uses detected toolchain

Outputs .ko file.

Example Template¶

#include <linux/module.h>
#include <linux/kernel.h>

static int __init hello_init(void) {
    pr_info("Hello, ELMOS!\n");
    return 0;
}

static void __exit hello_exit(void) {
    pr_info("Goodbye, ELMOS!\n");
}

module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");

Load in QEMU¶

After booting kernel:

insmod /path/to/module.ko
dmesg | tail

Userspace Apps¶

Create App¶

./build/elmos app create <name>

Generates template in examples/apps/<name>/ with Makefile and <name>.c.

Build App¶

cd examples/apps/<name>
make  # Cross-compiles for target

Outputs executable.

Example Template¶

#include <stdio.h>

int main() {
    printf("Hello from ELMOS app!\n");
    return 0;
}

Run in QEMU¶

Copy to rootfs and execute:

# In host
cp examples/apps/<name>/<name> build/rootfs/

# In QEMU
./<name>

Cross-Compilation¶

Auto-detects toolchain based on ./build/elmos arch
Sets CROSS_COMPILE and PATH
Falls back to LLVM if no toolchain

Templates¶

Customize templates in assets/templates/.

Examples¶

See examples/ for sample modules (e.g., char-test, hello-world) and apps.