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authorMatt Fleming <matt@console-pimps.org>2009-12-13 14:38:50 +0000
committerPaul Mundt <lethal@linux-sh.org>2009-12-17 14:31:20 +0900
commit5d9b4b19f118abfb75e352841f7bf74580d7e427 (patch)
tree5b9d0ec51bd12165d842d1d8a208e7568971757b /arch/sh/mm/init.c
parentb73c806341cfc7492ede6a2ce713cb579547d0ab (diff)
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 <matt@console-pimps.org> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh/mm/init.c')
-rw-r--r--arch/sh/mm/init.c6
1 files changed, 6 insertions, 0 deletions
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);