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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2008-02-09 18:24:37 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-02-09 18:24:41 +0100
commit6252d702c5311ce916caf75ed82e5c8245171c92 (patch)
tree3490f27b5f888ff2c1ec915d4e7201000f37a771 /arch/s390/mm/init.c
parent5a216a20837c5f5fa1ca4b8ae8991ffd96b08e6f (diff)
[S390] dynamic page tables.
Add support for different number of page table levels dependent on the highest address used for a process. This will cause a 31 bit process to use a two level page table instead of the four level page table that is the default after the pud has been introduced. Likewise a normal 64 bit process will use three levels instead of four. Only if a process runs out of the 4 tera bytes which can be addressed with a three level page table the fourth level is dynamically added. Then the process can use up to 8 peta byte. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm/init.c')
-rw-r--r--arch/s390/mm/init.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 248a71010700..8053245fe259 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -112,8 +112,9 @@ void __init paging_init(void)
init_mm.pgd = swapper_pg_dir;
S390_lowcore.kernel_asce = __pa(init_mm.pgd) & PAGE_MASK;
#ifdef CONFIG_64BIT
- S390_lowcore.kernel_asce |= _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
- pgd_type = _REGION2_ENTRY_EMPTY;
+ /* A three level page table (4TB) is enough for the kernel space. */
+ S390_lowcore.kernel_asce |= _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
+ pgd_type = _REGION3_ENTRY_EMPTY;
#else
S390_lowcore.kernel_asce |= _ASCE_TABLE_LENGTH;
pgd_type = _SEGMENT_ENTRY_EMPTY;