From mboxrd@z Thu Jan  1 00:00:00 1970
From: mhornung.linux@gmail.com (mhornung.linux at gmail.com)
Date: Sat, 28 Jun 2014 23:58:16 +0200
Subject: Delay in Printk Messages.
In-Reply-To: <53AEFC79.2020308@gmail.com>
References: <53AEFC79.2020308@gmail.com>
Message-ID: <20140628215814.GA28057@googlemail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hello Arun Kumar,

On Sat, 28. Jun 23:03, Arun Kumar wrote:
> I am able to read my printk messages in the kernel buffer only after 
> unloading the module..
> Is there some reason or configuration behind this.
> 
> I used a simple kernel module with only init and exit functions, and 
> after loading the module i cannot see the message printed by the 
> "module_init" function in the output given by "dmesg -c" I can see them 
> only after i unload the module.
> 

Since you do not provide your code I have to guess that your print
statement looks like this:

	  pr_debug("Hello World!");

Please notice that printk doesn't flush until a trailing newline is
provided (Linux Device Drivers Chapter 4). So maybe this is what you want:

	  pr_debug("Hello World!\n");

> i wait for around 15-20 seconds for the init message but it only shows 
> up on removing the module.
> 
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With best regards

Michael Hornung