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 <changwoo@igalia.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---
 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

"Guilherme G. Piccoli" <gpiccoli@igalia.com> 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 <changwoo@igalia.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 5 +++++
>  1 file changed, 5 insertions(+)

Applied, thanks.

jon

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 <changwoo@igalia.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

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

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