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

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

It can be helpful to set (enable) CONFIG_NULL_TTY so that the ttynull
driver is available. This avoids problems with stdin/stdout/stderr of
the init process. Howevere, CONFIG_NULL_TTY cannot be enabled by default
because it can be used by mistake, see the commit a91bd6223ecd ("Revert
"init/console: Use ttynull as a fallback when there is no console"").

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
[pmladek@suse.com: Slightly update wording.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220216203745.980-1-rdunlap@infradead.org
This commit is contained in:
Randy Dunlap 2022-02-16 12:37:45 -08:00 committed by Petr Mladek
parent 2ba3673d70
commit 96b02f2fbd

View File

@ -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 only console= parameter 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