Re: [Linux PPC] Disable PREEMPT

Christophe Leroy (CS GROUP)
2026-02-25T07:16:55Z

+Peter

Hi Christian,

Le 25/02/2026 à 06:54, Christian Zigotzky a écrit :
> Hello,
>
> We were previously able to disable PREEMPT in the kernel configuration,
> but the latest kernels now enable it by default and it is no longer
> possible to disable it.
>
> Is it possible to let us decide whether to activate PREEMPT or not?

Can you give more details on why you want to be able to deactivate PREEMPT ?

Read https://github.com/torvalds/linux/commit/7dadeaa6e851e

>
> Currently we use the following revert patch for our non-preempt kernels.
>
> --- a/kernel/Kconfig.preempt    2026-02-14 10:06:32.000000000 +0000
> +++ b/kernel/Kconfig.preempt    2026-02-08 21:03:27.000000000 +0000
> @@ -16,13 +16,11 @@ config ARCH_HAS_PREEMPT_LAZY
>
>  choice
>      prompt "Preemption Model"
> -    default PREEMPT_LAZY if ARCH_HAS_PREEMPT_LAZY
>      default PREEMPT_NONE
>
>  config PREEMPT_NONE
>      bool "No Forced Preemption (Server)"
>      depends on !PREEMPT_RT
> -    depends on ARCH_NO_PREEMPT
>      select PREEMPT_NONE_BUILD if !PREEMPT_DYNAMIC
>      help
>        This is the traditional Linux preemption model, geared towards
> @@ -37,7 +35,6 @@ config PREEMPT_NONE
>
>  config PREEMPT_VOLUNTARY
>      bool "Voluntary Kernel Preemption (Desktop)"
> -    depends on !ARCH_HAS_PREEMPT_LAZY
>      depends on !ARCH_NO_PREEMPT
>      depends on !PREEMPT_RT
>      select PREEMPT_VOLUNTARY_BUILD if !PREEMPT_DYNAMIC
>
> ---
>
> Thanks in advance,
>
> Christian
>