[PATCH] powerpc: enforce sane MAX_ORDER

[Kumar Gala]

On Sep 24, 2008, at 8:24 AM, Johannes Berg wrote:

> powerpc uses CONFIG_FORCE_MAX_ZONEORDER, and some things depend on it
> being at least 10 when 64k pages are not configured (notably the dart
> iommu code with CONFIG_PM). The defaults are fine, but when going  
> from a
> 64K pages config to one without 64K pages, MAX_ORDER stays at 9  
> which is
> too low for 4K pages.
>
> This patch makes the Kconfig enforce at least the defaults, I used 999
> as the upper bound for no particular reason other than that it's  
> plenty.
>
> Signed-off-by: Johannes Berg <johannes at sipsolutions.net>
> ---
>
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -415,8 +415,11 @@ config PPC_64K_PAGES
>
> config FORCE_MAX_ZONEORDER
> 	int "Maximum zone order"
> +	range 9 999 if PPC_64K_PAGES
> 	default "9" if PPC_64K_PAGES
> +	range 13 999 if PPC64 && !PPC_64K_PAGES
> 	default "13" if PPC64 && !PPC_64K_PAGES
> +	range 11 999
> 	default "11"
> 	help
> 	  The kernel memory allocator divides physically contiguous memory

Hope about setting the upper bound to 32 or 64.  Since I believe this  
in effect 2^FORCE_MAX_ZONEORDER, so 999 is just insane.  I'd almost  
prefer something like 16 since that might still be in the realm of  
reasonable and able to work.

- k