Enable/Disable pr_debug in Linux Device Driver

By default, the pr_debug messages are disabled. Consider the below sample code:

	#include <linux/module.h>
	#include <linux/kernel.h>
	static int myinit(void)
	{
	pr_alert("pr_alert\n");
	pr_crit("pr_crit\n");
	pr_err("pr_err");
	pr_warning("pr_warning\n");
	pr_notice("pr_notice\n");
	pr_info("pr_info\n");
	pr_debug("pr_debug\n");
	return 0;
	}
	static void myexit(void) { }
	module_init(myinit)
	module_exit(myexit)
	MODULE_LICENSE("GPL");

view raw hello.c hosted with ❤ by GitHub

Output:

You can see, pr_debug log was not displayed on the dmesg output.


To enable debugging output, build the appropriate file with -DDEBUG by adding
CFLAGS_[filename].o := -DDEBUG to the Makefile