Besides the possibility of userspace applications that care which one you use reading /proc/cmdline, what is the difference between using the kernel parameter quiet, versus loglevel=4, and the parameter debug, versus loglevel=7? Is there any?

2 Answers 2


Nope, they're absolutely the same. The following is a quote from Linux Kernel in a Nutshell by Greg Kroah-Hartman


Enable kernel debugging.

Cause the kernel log level to be set to the debug level, so that all debug messages will be printed to the console at boot time.


Disable all log messages.

Set the default kernel log level to KERN_WARNING (4), which suppresses all messages during boot except extremely serious ones. (Log levels are defined under the loglevel parameter.)


I don't see any messages with quiet or loglevel=0. I do see a (innocuous) message of failure with a value between 1-3 for loglevel. I see even more messages with values higher than that. It seems quiet is the same as loglevel=0, and debug is the same as loglevel=7.

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