/proc/sysrq-trigger documentation states that only first character is
processed and the rest is ignored, yet it is not recommended to write
any extra characters to it. The latter statement is contradictive as
these characters are also ignored as implied by preceding sentence.

Remove it.

Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
---
 Documentation/admin-guide/sysrq.rst | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst
index 9c7aa817adc72d..63ff415ce85d66 100644
--- a/Documentation/admin-guide/sysrq.rst
+++ b/Documentation/admin-guide/sysrq.rst
@@ -77,9 +77,7 @@ On other
 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.::
+	ignored. E.g.::
 
 		echo t > /proc/sysrq-trigger
 

base-commit: c746c3b5169831d7fb032a1051d8b45592ae8d78
-- 
An old man doll... just what I always wanted! - Clara

Bagas Sanjaya <bagasdotme@gmail.com> writes:

> /proc/sysrq-trigger documentation states that only first character is
> processed and the rest is ignored, yet it is not recommended to write
> any extra characters to it. The latter statement is contradictive as
> these characters are also ignored as implied by preceding sentence.
>
> Remove it.
>
> Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/
> Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
> ---
>  Documentation/admin-guide/sysrq.rst | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst
> index 9c7aa817adc72d..63ff415ce85d66 100644
> --- a/Documentation/admin-guide/sysrq.rst
> +++ b/Documentation/admin-guide/sysrq.rst
> @@ -77,9 +77,7 @@ On other
>  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.::
> +	ignored. E.g.::

I'm not sure this is right - there is a warning here that additional
characters may acquire a meaning in the future, so one should not
develop the habit of writing them now.  After all these years, I think
the chances of fundamental sysrq changes are pretty small, but I still
don't see why we would take the warning out?

jon

Hi. I am author of that sentence and this is NACK from me.

> I'm not sure this is right - there is a warning here that additional
> characters may acquire a meaning in the future, so one should not
> develop the habit of writing them now.

As you've said... I don't see anything confusing about that.
The warning was added for a reason, because there was discussion
about some people writing extra characters in there, which might
cause issues down the line if we refactor the code in future.

> After all these years, I think
> the chances of fundamental sysrq changes are pretty small,

Actualy it is not that long since the underscore mode was added...

> but I still don't see why we would take the warning out?

Exactly. Thank you.

Hi,

On 10/16/25 3:17 AM, Tomas Mudrunka wrote:
> Hi. I am author of that sentence and this is NACK from me.
> 
>> I'm not sure this is right - there is a warning here that additional
>> characters may acquire a meaning in the future, so one should not
>> develop the habit of writing them now.
> 
> As you've said... I don't see anything confusing about that.
> The warning was added for a reason, because there was discussion
> about some people writing extra characters in there, which might
> cause issues down the line if we refactor the code in future.

You have already provided a way to write (enter) multiple characters
to /proc/sysrq-trigger. Are you suggesting that someone may come
along and add yet another way to write multiple characters and that
this paragraph is present in case that happens?


>> After all these years, I think
>> the chances of fundamental sysrq changes are pretty small,
> 
> Actualy it is not that long since the underscore mode was added...
> 
>> but I still don't see why we would take the warning out?
> 
> Exactly. Thank you.
> 

-- 
~Randy

On Thu, Oct 16, 2025 at 12:17:58PM +0200, Tomas Mudrunka wrote:
> Hi. I am author of that sentence and this is NACK from me.

Oops, I didn't see your review when I send v2 [1].

[1]: https://lore.kernel.org/linux-doc/20251016103609.33897-2-bagasdotme@gmail.com/

> 
> > I'm not sure this is right - there is a warning here that additional
> > characters may acquire a meaning in the future, so one should not
> > develop the habit of writing them now.
> 
> As you've said... I don't see anything confusing about that.
> The warning was added for a reason, because there was discussion
> about some people writing extra characters in there, which might
> cause issues down the line if we refactor the code in future.

Any pointers to these discussions? Or do you have any idea on better
description on /proc/sysrq-trigger itself?

Confused...

-- 
An old man doll... just what I always wanted! - Clara

On 10/8/25 4:24 AM, Bagas Sanjaya wrote:
> /proc/sysrq-trigger documentation states that only first character is
> processed and the rest is ignored, yet it is not recommended to write
> any extra characters to it. The latter statement is contradictive as
> these characters are also ignored as implied by preceding sentence.
> 
> Remove it.
> 
> Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/
> Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

Thanks.

> ---
>  Documentation/admin-guide/sysrq.rst | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst
> index 9c7aa817adc72d..63ff415ce85d66 100644
> --- a/Documentation/admin-guide/sysrq.rst
> +++ b/Documentation/admin-guide/sysrq.rst
> @@ -77,9 +77,7 @@ On other
>  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.::
> +	ignored. E.g.::
>  
>  		echo t > /proc/sysrq-trigger
>  
> 
> base-commit: c746c3b5169831d7fb032a1051d8b45592ae8d78