Re: [PATCH 02/14] arm64: drop ranges in definition of ARCH_FORCE_MAX_ORDER

[Catalin Marinas]

On Thu, Mar 23, 2023 at 11:21:44AM +0200, Mike Rapoport wrote:
> From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
> 
> It is not a good idea to change fundamental parameters of core memory
> management. Having predefined ranges suggests that the values within
> those ranges are sensible, but one has to *really* understand
> implications of changing MAX_ORDER before actually amending it and
> ranges don't help here.
> 
> Drop ranges in definition of ARCH_FORCE_MAX_ORDER
> 
> Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
> ---
>  arch/arm64/Kconfig | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index e60baf7859d1..bab6483e4317 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1489,9 +1489,7 @@ config XEN
>  config ARCH_FORCE_MAX_ORDER
>  	int "Maximum zone order" if ARM64_4K_PAGES || ARM64_16K_PAGES
>  	default "13" if ARM64_64K_PAGES
> -	range 11 13 if ARM64_16K_PAGES
>  	default "11" if ARM64_16K_PAGES
> -	range 10 15 if ARM64_4K_PAGES
>  	default "10"

I don't mind rewriting the help text as in the subsequent patch but I'd
keep the ranges as a safety measure. It's less wasted time explaining to
people why some random max order doesn't work. Alternatively, we can
drop the ranges but make this option configurable only if EXPERT.

-- 
Catalin