KERN_DEBUG printk's at bootup not displayed in QEMU console?

Question

I am trying to debug and optimise the kernel bootup time. I am using QEMU for emulating the kernel. I have placed a few of my printk's with KERN_DEBUG but they are not being displayed on any of the terminals. I had to change them to KERN_INFO and then i can see the same.

My debug log level is 7. I have changed it when I configured the kernel.

Can anybody tell me if the prints are getting buffered to any other terminal?

Answer 1

I've actually run into this problem before..I ended up resolving this issue in a 'bad' way..

Try adding loglevel=8 to your kernel boot parameters.

Also, according to http://elinux.org/Debugging_by_printing
Only messages with a value lower (not lower equal) than the console_loglevel will be printed.