Starting with a hello world kernel module

Makefile

@@ -0,0 +1,8 @@
+obj-m := simplefs.o
+simplefs-objs := simple.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

simple.c

@@ -0,0 +1,26 @@
+/*
+ * A Simple Filesystem for the Linux Kernel.
+ *
+ * Initial author: Sankar P <sankar.curiosity@gmail.com>
+ * License: Creative Commons Zero License - http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+static int simplefs_init(void)
+{
+        printk(KERN_ALERT "Hello World\n");
+        return 0;
+}
+
+static void simplefs_exit(void)
+{
+        printk(KERN_ALERT "Goodbye World\n");
+}
+
+module_init(simplefs_init);
+module_exit(simplefs_exit);
+
+MODULE_LICENSE("CC0");
+MODULE_AUTHOR("Sankar P");