* [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters @ 2025-10-08 11:24 Bagas Sanjaya 2025-10-09 2:18 ` Randy Dunlap 2025-10-14 14:55 ` Jonathan Corbet 0 siblings, 2 replies; 10+ messages in thread From: Bagas Sanjaya @ 2025-10-08 11:24 UTC (permalink / raw) To: Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Jonathan Corbet, Cengiz Can, Bagas Sanjaya, Tomas Mudrunka, Jiri Slaby, Greg Kroah-Hartman, Anselm Schüler /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 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-08 11:24 [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters Bagas Sanjaya @ 2025-10-09 2:18 ` Randy Dunlap 2025-10-14 14:55 ` Jonathan Corbet 1 sibling, 0 replies; 10+ messages in thread From: Randy Dunlap @ 2025-10-09 2:18 UTC (permalink / raw) To: Bagas Sanjaya, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Jonathan Corbet, Cengiz Can, Tomas Mudrunka, Jiri Slaby, Greg Kroah-Hartman, Anselm Schüler 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 ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-08 11:24 [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters Bagas Sanjaya 2025-10-09 2:18 ` Randy Dunlap @ 2025-10-14 14:55 ` Jonathan Corbet 2025-10-14 17:57 ` Randy Dunlap 2025-10-16 10:17 ` Tomas Mudrunka 1 sibling, 2 replies; 10+ messages in thread From: Jonathan Corbet @ 2025-10-14 14:55 UTC (permalink / raw) To: Bagas Sanjaya, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Cengiz Can, Bagas Sanjaya, Tomas Mudrunka, Jiri Slaby, Greg Kroah-Hartman, Anselm Schüler 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 ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-14 14:55 ` Jonathan Corbet @ 2025-10-14 17:57 ` Randy Dunlap 2025-10-15 0:11 ` Bagas Sanjaya 2025-10-16 10:17 ` Tomas Mudrunka 1 sibling, 1 reply; 10+ messages in thread From: Randy Dunlap @ 2025-10-14 17:57 UTC (permalink / raw) To: Jonathan Corbet, Bagas Sanjaya, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Cengiz Can, Tomas Mudrunka, Jiri Slaby, Greg Kroah-Hartman, Anselm Schüler On 10/14/25 7:55 AM, Jonathan Corbet wrote: > 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? but the following paragraph says: Alternatively, write multiple characters prepended by underscore. This way, all characters will be processed. E.g.:: echo _reisub > /proc/sysrq-trigger so it is confuzing. -- ~Randy ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-14 17:57 ` Randy Dunlap @ 2025-10-15 0:11 ` Bagas Sanjaya 2025-10-15 6:18 ` Jiri Slaby 0 siblings, 1 reply; 10+ messages in thread From: Bagas Sanjaya @ 2025-10-15 0:11 UTC (permalink / raw) To: Randy Dunlap, Jonathan Corbet, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Cengiz Can, Tomas Mudrunka, Jiri Slaby, Greg Kroah-Hartman, Anselm Schüler [-- Attachment #1: Type: text/plain, Size: 2368 bytes --] On Tue, Oct 14, 2025 at 10:57:45AM -0700, Randy Dunlap wrote: > > > On 10/14/25 7:55 AM, Jonathan Corbet wrote: > > 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? > > but the following paragraph says: > > Alternatively, write multiple characters prepended by underscore. > This way, all characters will be processed. E.g.:: > > echo _reisub > /proc/sysrq-trigger > > so it is confuzing. I guess the whole "On all" description can be rewritten like: Write a single character to /proc/sysrq-trigger, e.g.:: <snipped>... If a string (multiple characters) is written instead, only the first character is processed unless the string is prepended by an underscore, like:: <snipped>... Thanks. -- An old man doll... just what I always wanted! - Clara [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-15 0:11 ` Bagas Sanjaya @ 2025-10-15 6:18 ` Jiri Slaby 2025-10-15 9:39 ` Bagas Sanjaya 0 siblings, 1 reply; 10+ messages in thread From: Jiri Slaby @ 2025-10-15 6:18 UTC (permalink / raw) To: Bagas Sanjaya, Randy Dunlap, Jonathan Corbet, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Cengiz Can, Tomas Mudrunka, Greg Kroah-Hartman, Anselm Schüler On 15. 10. 25, 2:11, Bagas Sanjaya wrote: > On Tue, Oct 14, 2025 at 10:57:45AM -0700, Randy Dunlap wrote: >> >> >> On 10/14/25 7:55 AM, Jonathan Corbet wrote: >>> 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? >> >> but the following paragraph says: >> >> Alternatively, write multiple characters prepended by underscore. >> This way, all characters will be processed. E.g.:: >> >> echo _reisub > /proc/sysrq-trigger >> >> so it is confuzing. > > I guess the whole "On all" description can be rewritten like: > > Write a single character to /proc/sysrq-trigger, e.g.:: > > <snipped>... > > If a string (multiple characters) is written instead, only the first character > is processed unless the string is prepended by an underscore, like:: > > <snipped>... Some kind of, yes. So Either: * you write no underscore and a character -- the rest is ignored and you should not write more than one. * you prepend underscore and write more of them -- all are processed. thanks, -- js suse labs ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-15 6:18 ` Jiri Slaby @ 2025-10-15 9:39 ` Bagas Sanjaya 0 siblings, 0 replies; 10+ messages in thread From: Bagas Sanjaya @ 2025-10-15 9:39 UTC (permalink / raw) To: Jiri Slaby, Randy Dunlap, Jonathan Corbet, Linux Kernel Mailing List, Linux Documentation, Linux Serial Cc: Cengiz Can, Tomas Mudrunka, Greg Kroah-Hartman, Anselm Schüler [-- Attachment #1: Type: text/plain, Size: 754 bytes --] On Wed, Oct 15, 2025 at 08:18:44AM +0200, Jiri Slaby wrote: > On 15. 10. 25, 2:11, Bagas Sanjaya wrote: > > I guess the whole "On all" description can be rewritten like: > > > > Write a single character to /proc/sysrq-trigger, e.g.:: > > > > <snipped>... > > > > If a string (multiple characters) is written instead, only the first character > > is processed unless the string is prepended by an underscore, like:: > > > > <snipped>... > > Some kind of, yes. So Either: > * you write no underscore and a character -- the rest is ignored and you > should not write more than one. > * you prepend underscore and write more of them -- all are processed. > OK, thanks! -- An old man doll... just what I always wanted! - Clara [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-14 14:55 ` Jonathan Corbet 2025-10-14 17:57 ` Randy Dunlap @ 2025-10-16 10:17 ` Tomas Mudrunka 2025-10-16 10:47 ` Bagas Sanjaya 2025-10-16 18:51 ` Randy Dunlap 1 sibling, 2 replies; 10+ messages in thread From: Tomas Mudrunka @ 2025-10-16 10:17 UTC (permalink / raw) To: corbet Cc: bagasdotme, cengiz, gregkh, jirislaby, linux-doc, linux-kernel, linux-serial, mail, tomas.mudrunka 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. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-16 10:17 ` Tomas Mudrunka @ 2025-10-16 10:47 ` Bagas Sanjaya 2025-10-16 18:51 ` Randy Dunlap 1 sibling, 0 replies; 10+ messages in thread From: Bagas Sanjaya @ 2025-10-16 10:47 UTC (permalink / raw) To: Tomas Mudrunka, corbet Cc: cengiz, gregkh, jirislaby, linux-doc, linux-kernel, linux-serial, mail [-- Attachment #1: Type: text/plain, Size: 925 bytes --] 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 [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters 2025-10-16 10:17 ` Tomas Mudrunka 2025-10-16 10:47 ` Bagas Sanjaya @ 2025-10-16 18:51 ` Randy Dunlap 1 sibling, 0 replies; 10+ messages in thread From: Randy Dunlap @ 2025-10-16 18:51 UTC (permalink / raw) To: Tomas Mudrunka, corbet Cc: bagasdotme, cengiz, gregkh, jirislaby, linux-doc, linux-kernel, linux-serial, mail 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 ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2025-10-16 18:51 UTC | newest] Thread overview: 10+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-10-08 11:24 [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters Bagas Sanjaya 2025-10-09 2:18 ` Randy Dunlap 2025-10-14 14:55 ` Jonathan Corbet 2025-10-14 17:57 ` Randy Dunlap 2025-10-15 0:11 ` Bagas Sanjaya 2025-10-15 6:18 ` Jiri Slaby 2025-10-15 9:39 ` Bagas Sanjaya 2025-10-16 10:17 ` Tomas Mudrunka 2025-10-16 10:47 ` Bagas Sanjaya 2025-10-16 18:51 ` Randy Dunlap
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