kernel modules

kernel modules are runtime loadable object files
they are placed in the /mod folder of the initial ramdisk and sysroot

creating a kernel module

creating a kernel module is simple just add your c source file into the modules of the main stanix repo and run make

writing a kernel module

the most simple kernel module is

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

int init(int argc,char **argv){
    kdebugf("hello world !\n");
    return 0;
}

int fini(){
    return 0;
}

kmodule module_meta = {
    .init = init,
    .fini = fini,
    .description = "hello world",
    .name = "hello module",
}

on the first line we include <kernel/module.h> , all kernel header (except arch specific one) are accessible trought <kernel/XXX.h>
<kernel/module.h> define some macro and the kmodule struct to define module meta data

module_meta all kernel module must have a kmodule struct call module_meta it give the module loader information about the module

• init : define the function called when the module is added (here the init function)
• fini : define the function called before the module is unloaded (here the fini function)
• author (optional) : define the author of the module
• description (optional)
• liscence (optional)
• name : the name used to reference the module (the name showed in /proc/modules , … )

[!NOTE] while kernel modules can reference all the core kernel symbols if a kernel module don’t export a symbol using the EXPORT(sym) macro (defined in <kernel/modules.h>) it is inacesible from other kernel modules

[!NOTE] a lot of string function are avalible for kernel se
don’t forget to include <kernel/string.h> instead of <string.h>

[!WARNING] kernel modules must be in C , C++ won’t work for the moment (it’s a work in progress)

memory allocation

memory allocation functions are avalible under <kernel/kheap.h>
you can use void * kmalloc(size_t amount) and void kfree(void *ptr)