linux-kernel - [PATCH v2] Documentation: sysrq: Rewrite /proc/sysrq-trigger usage

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Message-ID: <20251016103609.33897-2-bagasdotme@gmail.com>
Date: Thu, 16 Oct 2025 17:36:10 +0700
From: Bagas Sanjaya <bagasdotme@...il.com>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Documentation <linux-doc@...r.kernel.org>,
	Linux Serial <linux-serial@...r.kernel.org>
Cc: Jonathan Corbet <corbet@....net>,
	Cengiz Can <cengiz@...nel.wtf>,
	Bagas Sanjaya <bagasdotme@...il.com>,
	Tomas Mudrunka <tomas.mudrunka@...il.com>,
	Jiri Slaby <jirislaby@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Anselm Schüler <mail@...elmschueler.com>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH v2] Documentation: sysrq: Rewrite /proc/sysrq-trigger usage

/proc/sysrq-trigger usage documentation (in "On all" section) states
that it is not recommended to write extra characters to it to avoid
undefined behavior, which is contradictive to previous sentence that
such characters are ignored. Also, in order to actually process them
(as a string), prepending it with underscore is required.

Rewrite the description.

Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/
Signed-off-by: Bagas Sanjaya <bagasdotme@...il.com>
---
Changes since v1 [1]:

  - Rewrite the whole "On all" section (Jon, Randy)

[1]: https://lore.kernel.org/linux-doc/20251008112409.33622-1-bagasdotme@gmail.com/

 Documentation/admin-guide/sysrq.rst | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst
index 9c7aa817adc72d..6157d93e03a1e2 100644
--- a/Documentation/admin-guide/sysrq.rst
+++ b/Documentation/admin-guide/sysrq.rst
@@ -75,16 +75,13 @@ On other
 	submit a patch to be included in this section.
 
 On all
-	Write a single character to /proc/sysrq-trigger.
-	Only the first character is processed, the rest of the string is
-	ignored. However, it is not recommended to write any extra characters
-	as the behavior is undefined and might change in the future versions.
-	E.g.::
+	Write a single character to /proc/sysrq-trigger. E.g.::
 
 		echo t > /proc/sysrq-trigger
 
-	Alternatively, write multiple characters prepended by underscore.
-	This way, all characters will be processed. E.g.::
+	If a string (multiple characters) is written instead, only the
+	first character is processed unless the string is prepended by
+	an underscore, like::
 
 		echo _reisub > /proc/sysrq-trigger
 

base-commit: a1af37b935c73049c54cb1412cf0850212af420e
-- 
An old man doll... just what I always wanted! - Clara