On Mon, Apr 14, 2014 at 06:24:55PM +0900, Jungseok Lee wrote: > On Monday, April 14, 2014 6:14 PM, Steve Capper wrote: > > On Mon, Apr 13, 2014 at 04:41:07PM +0900, Jungseok Lee wrote: > > > This patch implements 4 levels of translation tables since 3 levels of > > > page tables with 4KB pages cannot support 40-bit physical address > > > space described in [1] due to the following issue. > > > > > > It is a restriction that kernel logical memory map with 4KB + 3 levels > > > (0xffffffc000000000-0xffffffffffffffff) cannot cover RAM region from > > > 544GB to 1024GB in [1]. Specifically, ARM64 kernel fails to create > > > mapping for this region in map_mem function since __phys_to_virt for > > > this region reaches to address overflow. > > > > > > If SoC design follows the document, [1], over 32GB RAM would be placed > > > from 544GB. Even 64GB system is supposed to use the region from 544GB > > > to 576GB for only 32GB RAM. Naturally, it would reach to enable 4 > > > levels of page tables to avoid hacking __virt_to_phys and __phys_to_virt. > > > > > > However, it is recommended 4 levels of page table should be only > > > enabled if memory map is too sparse or there is about 512GB RAM. > > > > Hi, > > So I thought I'd apply this series and have a play, this patch doesn't apply cleanly for me, please > > see below why... > > This pathset is based on 3.15-rc1. Thanks, yes that applies cleanly for me now. > > > [ ... ] > > > > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index > > > 0fd5650..0b0b16a 100644 > > > --- a/arch/arm64/kernel/head.S > > > +++ b/arch/arm64/kernel/head.S > > > @@ -46,8 +46,8 @@ > > > #error KERNEL_RAM_VADDR must start at 0xXXX80000 #endif > > > > > > -#define SWAPPER_DIR_SIZE (3 * PAGE_SIZE) > > > -#define IDMAP_DIR_SIZE (2 * PAGE_SIZE) > > > +#define SWAPPER_DIR_SIZE (4 * PAGE_SIZE) > > > +#define IDMAP_DIR_SIZE (3 * PAGE_SIZE) > > > > > > .globl swapper_pg_dir > > > .equ swapper_pg_dir, KERNEL_RAM_VADDR - SWAPPER_DIR_SIZE > > > @@ -384,6 +384,20 @@ ENDPROC(__calc_phys_offset) > > > .endm > > > > > > /* > > > + * Macro to populate the PUD for the corresponding block entry in the > > > +next > > > + * level (tbl) for the given virtual address. > > > + * > > > + * Preserves: pud, tbl, virt > > > + * Corrupts: tmp1, tmp2 > > > + */ > > > + .macro create_pud_entry, pud, tbl, virt, tmp1, tmp2 > > > + lsr \tmp1, \virt, #PUD_SHIFT > > > + and \tmp1, \tmp1, #PTRS_PER_PUD - 1 // PUD index > > > + orr \tmp2, \tbl, #3 // PUD entry table type > > > + str \tmp2, [\pud, \tmp1, lsl #3] > > > + .endm > > > + > > > +/* > > > * Macro to populate block entries in the page table for the start..end > > > * virtual range (inclusive). > > > * > > > @@ -445,10 +459,18 @@ __create_page_tables: > > > ldr x3, =KERNEL_START > > > add x3, x3, x28 // __pa(KERNEL_START) > > > > I don't think we have C++ style comments in the kernel. Also, I can't see any references to > > =KERNEL_START in arch/arm64/kernel/head.S (from 3.14 down). > > C++ style comments are prevalent in arch/arm64/kernel/head.S. I've followed the > code style written previously. Apologies, my mistake, I've been staring at arch/arm too long where @ is used. Cheers, -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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