Where are my printk messages?

[chris123]

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#

[gerard4143]

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

[chris123]

No, I'm inserting it right on the box I'm compiling it on.

[gerard4143]

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...

[chris123]

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

[gerard4143]

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

//#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

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

[umeshkmahindrakar]

Hi

you printk messages will be in /var/log/messages/dmesg

or just type

dmesg
at the end you will see you printk message