Howto build a kernel module out of the kernel tree
From KoanSoftware Wiki
Yocto recipe to build a kernel module out of the kernel tree
While it is always preferable to work with sources integrated into the Linux kernel sources, if you need an external kernel module, you could start from this simple recipe based on Yocto Project kernel Development Manual. This GPL2 recipe is available as a template from which you can create your own out-of-tree Linux kernel module recipe.
$ tree . ├── files │ ├── COPYING │ ├── hellokernel.c │ └── Makefile └── kernmodule.bb
COPYING
Copy COPYING file into your files
cp meta-skeleton/recipes-kernel/hello-mod/files/COPYING YOURPATH/kernmodule/files/
kernmodule.bb
# # Yocto recipe to build a kernel module out of the kernel tree # kernmodule.bb # Marco Cavallini - KOAN sas - www.koansoftware.com # DESCRIPTION = "Hello kernel module out of the kernel tree" SECTION = "examples" LICENSE = "GPLv2" LIC_FILES_CHKSUM = "file://COPYING;md5=12f884d2ae1ff87c09e5b7ccc2c4ca7e" PR = "r0" inherit module SRC_URI = "file://hellokernel.c \ file://Makefile \ file://COPYING \ " S = "${WORKDIR}"
Makefile
obj-m += hellokernel.o SRC := $(shell pwd) all: $(MAKE) -C $(KERNEL_SRC) M=$(SRC) modules modules_install: $(MAKE) -C $(KERNEL_SRC) M=$(SRC) modules_install
hellokernel.c
/* * hello.c - The simplest and dirty kernel module */ #include <linux/module.h> #include <linux/kernel.h> int init_module(void) { printk(KERN_INFO "Hello world\n"); return 0; } void cleanup_module(void) { printk(KERN_INFO "Goodbye world\n"); }