| |
| <previous description obsolete, deleted> |
| |
| Virtual memory map with 4 level page tables: |
| |
| 0000000000000000 - 00007fffffffffff (=47bits) user space, different per mm |
| hole caused by [48:63] sign extension |
| ffff800000000000 - ffff80ffffffffff (=40bits) guard hole |
| ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of phys. memory |
| ffffc10000000000 - ffffc1ffffffffff (=40bits) hole |
| ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space |
| ... unused hole ... |
| ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0 |
| ... unused hole ... |
| ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space |
| |
| vmalloc space is lazily synchronized into the different PML4 pages of |
| the processes using the page fault handler, with init_level4_pgt as |
| reference. |
| |
| Current X86-64 implementations only support 40 bit of address space, |
| but we support upto 46bits. This expands into MBZ space in the page tables. |
| |
| -Andi Kleen, Jul 2004 |
