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I'm trying to create a proc entry. My init_module function is as below
int init_module()
{
printk(KERN_INFO "proc2:Module Loaded\n");
proc_entry=proc_create_data(proc_name,0644,NULL,&fops,NULL);
if(proc_entry==NULL)
{
printk(KERN_INFO "proc2:Error registering proc entry");
}
else
{
printk(KERN_INFO "proc2:Proc Entry Created");
}
return 0;
}
following is cleanup method
void cleanup_module()
{
printk(KERN_INFO "proc2:module unloaded");
remove_proc_entry(proc_name,proc_entry);
}
rest of program include variable definition and callback functions.
when i compile this program it compiles well.
when i use insmod it doesn't reply me prompt.
lsmod lists my module and shows used by one (don't know what).
dmesg shows none of the above printk messages.
can you tell me what's wrong here?
327
All printk() messages are printed to the kernel log buffer, which is a ring buffer exported to userspace through /dev/kmsg. The usual way to read it is using dmesg .
printk is a C function from the Linux kernel interface that prints messages to the kernel log. It accepts a string parameter called the format string, which specifies a method for rendering an arbitrary number of varied data type parameter(s) into a string. The string is then printed to the kernel log.
Printk is implemented by using a ring buffer in the kernel with a size of __LOG_BUF_LEN bytes where __LOG_BUF_LEN equals (1 << CONFIG_LOG_BUF_SHIFT) (see kernel/printk. c for details).
The console log level can also be changed by the klogd program, or by writing the specified level to the /proc/sys/kernel/printk file. The kernel log levels are: 0 (KERN_EMERG) The system is unusable.
Try echo "7" > /proc/sys/kernel/printk to enable all console log levels.
The numbers are corresponding to below:
#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*/
The default number is 4, which allows console to show messages only at least in KERN_WARNING.
That's why you cannot see log in KERN_INFO level.
111
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