lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

sh: Definitions for 3-level page table layout

Browse Source 
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>
This commit is contained in:
Matt Fleming
2009-12-13 14:38:50 +00:00
committed by Paul Mundt
parent b73c806341
commit 5d9b4b19f1
7 changed files with 134 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/sh/mm/init.c
View File

@@ -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);