[PATCH] loglevel boot option

Add a boot-time option to set the loglevel.  We already have `quiet' and
`debug', which set it to specific levels.  This is better.  
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/kernel-parameters.txt

@@ -634,6 +634,20 @@ running once the system is up.
 	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
 			Format: <irq>
 
+	loglevel=	All Kernel Messages with a loglevel smaller than the
+			console loglevel will be printed to the console. It can
+			also be changed with klogd or other programs. The
+			loglevels are defined as follows:
+
+			0 (KERN_EMERG)		system is unusable
+			1 (KERN_ALERT)		action must be taken immediately
+			2 (KERN_CRIT)		critical conditions
+			3 (KERN_ERR)		error conditions
+			4 (KERN_WARNING)	warning conditions
+			5 (KERN_NOTICE)		normal but significant condition
+			6 (KERN_INFO)		informational
+			7 (KERN_DEBUG)		debug-level messages
+
 	log_buf_len=n	Sets the size of the printk ring buffer, in bytes.
 			Format is n, nk, nM.  n must be a power of two.  The
 			default is set in kernel config.

init/main.c

@@ -209,6 +209,14 @@ static int __init quiet_kernel(char *str)
 __setup("debug", debug_kernel);
 __setup("quiet", quiet_kernel);
 
+static int __init loglevel(char *str)
+{
+	get_option(&str, &console_loglevel);
+	return 1;
+}
+
+__setup("loglevel=", loglevel);
+
 /*
  * Unknown boot options get handed to init, unless they look like
  * failed parameters