blob: 662b73971a67b22eddf99b5b975da893b72a0b40 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001
2<previous description obsolete, deleted>
3
4Virtual memory map with 4 level page tables:
5
60000000000000000 - 00007fffffffffff (=47bits) user space, different per mm
7hole caused by [48:63] sign extension
8ffff800000000000 - ffff80ffffffffff (=40bits) guard hole
9ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of phys. memory
10ffffc10000000000 - ffffc1ffffffffff (=40bits) hole
11ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space
12... unused hole ...
13ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0
14... unused hole ...
15ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space
16
17vmalloc space is lazily synchronized into the different PML4 pages of
18the processes using the page fault handler, with init_level4_pgt as
19reference.
20
21Current X86-64 implementations only support 40 bit of address space,
22but we support upto 46bits. This expands into MBZ space in the page tables.
23
24-Andi Kleen, Jul 2004