On 07/12/2015 12:36 AM, Greg KH wrote:
On Sat, Jul 11, 2015 at 11:06:30PM +1000, Orion Agali wrote:
I'm using Arch and I cannot figure out how to get printk debug messages to display in journalctl.
I tried the following: * Set LogLevel=debug in /etc/systemd/systemd.conf * Add kernel parameter 'debug' on boot * Setting loglevel=8 in /proc/sys/kernel/printk * dmsg -n 8
Consider the following module:
---------- #include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> static int __init task1_init(void) { pr_notice("I am at level notice"); pr_debug("I am at level debug."); return 0; } static void __exit task1_exit(void){} module_init(task1_init); module_exit(task1_exit); ------------
The notice level is printed but the debug level is not. The debug message is not in dmesg or /dev/kmsg either
The answer is probably straight forward, but I've hit a wall so I'm hoping somebody here will be able to point me in the right direction Take a look at Documentation/dynamic-debug-howto.txt for how to get pr_debug() working properly for your module.
Great reference! After reading and testing I realize I can * activate at compile time using -DDEBUG * use dyndbg in the module paramaters * add queries to <debugfs>/dynamic_debug/control * use dyndbg in the boot string Thank you.