[PATCH] Docs: printk: add 'console=null|""' to admin/kernel-parameters

[Randy Dunlap]

Tell about 'console=null|""' and how to use it.

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
---
 Documentation/admin-guide/kernel-parameters.txt |    6 ++++++
 1 file changed, 6 insertions(+)

--- linux-next-20220214.orig/Documentation/admin-guide/kernel-parameters.txt
+++ linux-next-20220214/Documentation/admin-guide/kernel-parameters.txt
@@ -724,6 +724,12 @@
 		hvc<n>	Use the hypervisor console device <n>. This is for
 			both Xen and PowerPC hypervisors.
 
+		{ null | "" }
+			Use to disable console output, i.e., to have kernel
+			console messages discarded.
+			This must be the first (or only) console= string
+			used on the kernel command line.
+
 		If the device connected to the port is not a TTY but a braille
 		device, prepend "brl," before the device type, for instance
 			console=brl,ttyS0