[PATCH kernel] powerpc: Bump minimum zone order for 4K system page size

[Balbir Singh]

On 23/09/16 14:51, Alexey Kardashevskiy wrote:
> The moderm kernel on powernv platform cannot possibly boot with values
> less than 12 as the default DMA window of 2GB requires
> (2<<30)/4096 TCEs which is 4MB of contiguous memory, log2(4M) == 22
> so anything less than 12 won't work.
> 
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> 
> I am hitting this when switching the system page size from 64K to 4K and
> back. When I switch to 64K, zone order is set to 9 by default and
> it does not change when I switch to 4K as 9 is still within the limits.
> And there are other folks complaining about this too.
> ---
>  arch/powerpc/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 927d2ab..3516f16 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -637,7 +637,7 @@ config FORCE_MAX_ZONEORDER
>  	int "Maximum zone order"
>  	range 8 9 if PPC64 && PPC_64K_PAGES
>  	default "9" if PPC64 && PPC_64K_PAGES
> -	range 9 13 if PPC64 && !PPC_64K_PAGES
> +	range 12 13 if PPC64 && !PPC_64K_PAGES
>  	default "13" if PPC64 && !PPC_64K_PAGES
>  	range 9 64 if PPC32 && PPC_16K_PAGES
>  	default "9" if PPC32 && PPC_16K_PAGES
> 

Aneesh already submitted a patch for this

Balbir Singh.