From a7ee539584acf4a565b7439ceaea8401ec210353 Mon Sep 17 00:00:00 2001 From: Rashmica Gupta Date: Fri, 19 Feb 2016 16:38:47 +1100 Subject: [PATCH] powerpc/Kconfig: Update config option based on page size. Currently on PPC64 changing kernel pagesize from 4K to 64K leaves FORCE_MAX_ZONEORDER set to 13 - which produces a compile error. The error occurs because of the following constraint (from include/linux/mmzone.h) being violated: MAX_ORDER -1 + PAGESHIFT <= SECTION_SIZE_BITS. Expanding this out, we get: FORCE_MAX_ZONEBITS <= 25 - PAGESHIFT, which requires, for a 64K page, FORCE_MAX_ZONEBITS <= 9. Thus set max value of FORCE_MAX_ZONEORDER for 64K pages to 9, and 4K pages to 13. Also, check the minimum value: In include/linux/huge_mm.h, we have the constraint HPAGE_PMD_ORDER < MAX_ORDER which expands out to: PTE_INDEX_SIZE < FORCE_MAX_ZONEORDER. PTE_INDEX_SIZE is: 9 (4k hash or no hash 4K pgtable) or 8 (64K hash or no hash 64K pgtable). Thus a min value of 8 for 64K pages and 9 for 4K pages is reasonable. So, update the range of FORCE_MAX_ZONEORDER from 9-64 to 8-9 for 64K pages and from 13-64 to 9-13 for 4K pages. Signed-off-by: Rashmica Gupta Reviewed-by: Balbir Singh Signed-off-by: Michael Ellerman --- arch/powerpc/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 7cd32c038286..fbebde0771c8 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -605,9 +605,9 @@ endchoice config FORCE_MAX_ZONEORDER int "Maximum zone order" - range 9 64 if PPC64 && PPC_64K_PAGES + range 8 9 if PPC64 && PPC_64K_PAGES default "9" if PPC64 && PPC_64K_PAGES - range 13 64 if PPC64 && !PPC_64K_PAGES + range 9 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 -- GitLab