From 96b02f2fbde29a08ac7239fd9ba87ff870cf8a94 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Wed, 16 Feb 2022 12:37:45 -0800 Subject: [PATCH] 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 Cc: Petr Mladek Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: John Ogness Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org [pmladek@suse.com: Slightly update wording.] Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220216203745.980-1-rdunlap@infradead.org --- Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 49f495c9a7f8..46bfadf02bc7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -724,6 +724,12 @@ hvc Use the hypervisor console device . 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 -- 2.11.0