Smith Norton (smith.norton@xxxxxxxxx) wrote:
> I am trying the following kernel module in Ubuntu-6.06 LTS. I am using
> the kernel that came along with Ubuntu.
>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/init.h>
>
> MODULE_LICENSE("GPL");
>
> static int __init helloinit(void)
> {
> printk(KERN_ALERT, "[helloinit1]\n");
printk(KERN_ALERT "[helloinit1]\n");
=> without coma.
> printk("[helloinit2]\n");
> return 0;
> }
>
> static void __exit helloexit(void)
> {
> printk(KERN_ALERT, "[helloexit1]\n");
> printk("[helloexit2]\n");
> }
>
> module_init(helloinit);
> module_exit(helloexit);
>
> After compiling it with 'make', I 'insmod' it and then 'rmmod' it
> twice. The last few lines of /var/log/kern.log are as follows:-
>
> Dec 11 23:14:40 localhost kernel: [4295711.583000] <1><1>[helloinit2]
> Dec 11 23:14:45 localhost kernel: [4298099.296000] [helloexit2]
> Dec 11 23:15:22 localhost kernel: [4298136.092000] [helloinit2]
> Dec 11 23:15:27 localhost kernel: [4298141.000000] [helloexit2]
>
> 1. According to LKMPG '[helloinit1]' and '[helloexit1]' should have
> been printed. Why weren't they printed. Instead the <1> (KERN_ALERT)
> was printed. Here are all the macro defintions in my Ubuntu box:-
>
> smith@smithbox:~/kernel/exp$ grep "define"
> /usr/src/linux-headers-`uname -r`/include/linux/kernel.h | grep
> "KERN_"
> #define KERN_EMERG "<0>" /* system is unusable */
> #define KERN_ALERT "<1>" /* action must be taken immediately */
> #define KERN_CRIT "<2>" /* critical conditions */
> #define KERN_ERR "<3>" /* error conditions */
> #define KERN_WARNING "<4>" /* warning conditions */
> #define KERN_NOTICE "<5>" /* normal but significant condition */
> #define KERN_INFO "<6>" /* informational */
> #define KERN_DEBUG "<7>" /* debug-level messages */
>
> smith@smithbox:~/kernel/exp$ grep "int printk("
> /usr/src/linux-headers-`uname -r`/include/linux/kernel.h
> asmlinkage int printk(const char * fmt, ...)
> static inline int printk(const char *s, ...)
> static inline int printk(const char *s, ...) { return 0; }
>
> Why aren't '[helloinit1]' and '[helloexit1]' getting printed?
>
> 2. According to the sequence of statements, the output should have been:-
>
> <1>[helloinit2]
> <1>[helloexit2]
> <1>[helloinit2]
> <1>[helloexit2]
>
> But the output instead is:-
>
> <1><1>[helloinit2]
> [helloexit2]
> [helloinit2]
> [helloexit2]
>
> Why?
See : http://www.xml.com/ldd/chapter/book/ch04.html#t1
Have a nice day,
Regards,
Christophe
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