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

Mike Rapoport
2023-03-23T10:40:47Z

On Thu, Mar 23, 2023 at 10:15:33AM +0000, Catalin Marinas wrote:
> On Thu, Mar 23, 2023 at 11:21:44AM +0200, Mike Rapoport wrote:
> > From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> >
> > 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@kernel.org>
> > ---
> > 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.

I like the EXPERT alternative more. I'll add it in v2.

> --
> Catalin

--
Sincerely yours,
Mike.