Where are my printk messages?

02-01-2009	#1 (permalink)
chris123 Just Joined! Join Date: Jan 2009 Posts: 8	Where are my printk messages? I'm using Slack 8.1 and succesfully compiled the helloworld module. I can load the module with insmod, I can then see it loaded with lsmod and I can unload it with rmmod. However, I never see my printk messages anywhere. I tried doing a cat of /var/log/messages and /var/log/syslog but don't see my output. I'm doing all this work via ssh if that makes any diference. Chris root@slack-8-1:/usr/src/hellomod# cat hello.c #define MODULE #define LINUX #define __KERNEL__ #include <linux/module.h> #include <linux/kernel.h> MODULE_LICENSE("Dual BSD/GPL"); static int hello_init(void){ printk("<1> Hello Mod Init!\n"); return 0; } static void hello_exit(void){ printk(KERN_WARNING "Hello Mod Exit!\n"); } module_init(hello_init); module_exit(hello_exit); root@slack-8-1:/usr/src/hellomod# root@slack-8-1:/usr/src/hellomod# lsmod Module Size Used by Not tainted pcmcia_core 40896 0 ide-scsi 7456 0 eepro100 17264 1 root@slack-8-1:/usr/src/hellomod# insmod hello.o root@slack-8-1:/usr/src/hellomod# lsmod Module Size Used by Not tainted hello 336 0 (unused) pcmcia_core 40896 0 ide-scsi 7456 0 eepro100 17264 1 root@slack-8-1:/usr/src/hellomod# rmmod hello root@slack-8-1:/usr/src/hellomod# ls mod /bin/ls: mod: No such file or directory root@slack-8-1:/usr/src/hellomod# lsmod Module Size Used by Not tainted pcmcia_core 40896 0 ide-scsi 7456 0 eepro100 17264 1 root@slack-8-1:/usr/src/hellomod#

02-02-2009	#2 (permalink)
gerard4143 Linux Enthusiast Join Date: Dec 2007 Location: Canada, Prince Edward Island Posts: 618	Are you inserting this "hello world" module into a remote kernel? If you are then the printk results are probably on the remote machine...Hope this Helps Gerard4143 Welcome to the forums

02-02-2009	#3 (permalink)
chris123 Just Joined! Join Date: Jan 2009 Posts: 8	No, I'm inserting it right on the box I'm compiling it on.

02-02-2009

#4 (permalink)

gerard4143

Linux Enthusiast

Join Date: Dec 2007

Location: Canada, Prince Edward Island

Posts: 618

Quote:

Originally Posted by chris123

I'm doing all this work via ssh if that makes any diference.

If your compiling and inserting on a local machine...why are you using ssh...

02-02-2009	#5 (permalink)
chris123 Just Joined! Join Date: Jan 2009 Posts: 8	Becuase my wife demands I sit in the front room with her while she watches TV, but that's a whole other story. Anyway, I just tried it right from the console and I still don't see them. Chris

02-02-2009

#6 (permalink)

gerard4143

Linux Enthusiast

Join Date: Dec 2007

Location: Canada, Prince Edward Island

Posts: 618

I tried compiling your Hello world module and it worked...the message(s) appeared in the /var/log/messages file...kernel - 2.6.27.7-9-default x86_64 GNU/Linux

Code:

//#define MODULE
//#define LINUX
//#define __KERNEL__

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

MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)
{
	printk("<1> Hello Mod Init!\n");
	return 0;
}

static void hello_exit(void)
{
	printk(KERN_WARNING "Hello Mod Exit!\n");
}

module_init(hello_init);
module_exit(hello_exit);

Makefile

Code:

obj-m += test.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

02-12-2009	#7 (permalink)
umeshkmahindrakar Just Joined! Join Date: Jan 2009 Location: Bangalore Posts: 14	Where are my printk messages? Hi you printk messages will be in /var/log/messages/dmesg or just type dmesg at the end you will see you printk message