2024-02-03 15:22:43

by Guilherme G. Piccoli

[permalink] [raw]
Subject: [PATCH] docs: Document possible_cpus parameter

The number of possible CPUs is set be kernel in early boot time through
some discovery mechanisms, like ACPI in x86. We have a parameter both
in x86 and S390 to override that - there are some cases of BIOSes exposing
more possible CPUs than the available ones, so this parameter is a good
testing mechanism, but for some reason wasn't mentioned so far in the
kernel parameters guide - let's fix that.

Cc: Changwoo Min <[email protected]>
Signed-off-by: Guilherme G. Piccoli <[email protected]>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 31b3a25680d0..e553740190ea 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4644,6 +4644,11 @@
may be specified.
Format: <port>,<port>....

+ possible_cpus= [SMP,S390,X86]
+ Format: <unsigned int>
+ Set the number of possible CPUs, overriding the
+ regular discovery mechanisms (such as ACPI/FW, etc).
+
powersave=off [PPC] This option disables power saving features.
It specifically disables cpuidle and sets the
platform machine description specific power_save
--
2.43.0



2024-02-03 17:19:31

by Randy Dunlap

[permalink] [raw]
Subject: Re: [PATCH] docs: Document possible_cpus parameter



On 2/3/24 07:21, Guilherme G. Piccoli wrote:
> The number of possible CPUs is set be kernel in early boot time through
> some discovery mechanisms, like ACPI in x86. We have a parameter both
> in x86 and S390 to override that - there are some cases of BIOSes exposing
> more possible CPUs than the available ones, so this parameter is a good
> testing mechanism, but for some reason wasn't mentioned so far in the
> kernel parameters guide - let's fix that.
>
> Cc: Changwoo Min <[email protected]>
> Signed-off-by: Guilherme G. Piccoli <[email protected]>

Reviewed-by: Randy Dunlap <[email protected]>

Thanks.

> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 31b3a25680d0..e553740190ea 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4644,6 +4644,11 @@
> may be specified.
> Format: <port>,<port>....
>
> + possible_cpus= [SMP,S390,X86]
> + Format: <unsigned int>
> + Set the number of possible CPUs, overriding the
> + regular discovery mechanisms (such as ACPI/FW, etc).
> +
> powersave=off [PPC] This option disables power saving features.
> It specifically disables cpuidle and sets the
> platform machine description specific power_save

--
#Randy

2024-02-05 17:22:43

by Jonathan Corbet

[permalink] [raw]
Subject: Re: [PATCH] docs: Document possible_cpus parameter

"Guilherme G. Piccoli" <[email protected]> writes:

> The number of possible CPUs is set be kernel in early boot time through
> some discovery mechanisms, like ACPI in x86. We have a parameter both
> in x86 and S390 to override that - there are some cases of BIOSes exposing
> more possible CPUs than the available ones, so this parameter is a good
> testing mechanism, but for some reason wasn't mentioned so far in the
> kernel parameters guide - let's fix that.
>
> Cc: Changwoo Min <[email protected]>
> Signed-off-by: Guilherme G. Piccoli <[email protected]>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +++++
> 1 file changed, 5 insertions(+)

Applied, thanks.

jon