From 5d9b4b19f118abfb75e352841f7bf74580d7e427 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Sun, 13 Dec 2009 14:38:50 +0000 Subject: sh: Definitions for 3-level page table layout If using 64-bit PTEs and 4K pages then each page table has 512 entries (as opposed to 1024 entries with 32-bit PTEs). Unlike MIPS, SH follows the convention that all structures in the page table (pgd_t, pmd_t, pgprot_t, etc) must be the same size. Therefore, 64-bit PTEs require 64-bit PGD entries, etc. Using 2-levels of page tables and 64-bit PTEs it is only possible to map 1GB of virtual address space. In order to map all 4GB of virtual address space we need to adopt a 3-level page table layout. This actually works out better for CONFIG_SUPERH32 because we only waste 2 PGD entries on the P1 and P2 areas (which are untranslated) instead of 256. Signed-off-by: Matt Fleming Signed-off-by: Paul Mundt --- arch/sh/mm/init.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/sh/mm/init.c') diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c index 432acd07e76a..761910d142f8 100644 --- a/arch/sh/mm/init.c +++ b/arch/sh/mm/init.c @@ -120,7 +120,13 @@ void __init page_table_range_init(unsigned long start, unsigned long end, for ( ; (i < PTRS_PER_PGD) && (vaddr != end); pgd++, i++) { pud = (pud_t *)pgd; for ( ; (j < PTRS_PER_PUD) && (vaddr != end); pud++, j++) { +#ifdef __PAGETABLE_PMD_FOLDED pmd = (pmd_t *)pud; +#else + pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE); + pud_populate(&init_mm, pud, pmd); + pmd += k; +#endif for (; (k < PTRS_PER_PMD) && (vaddr != end); pmd++, k++) { if (pmd_none(*pmd)) { pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE); -- cgit v1.2.2