projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | |
| 2 | <previous description obsolete, deleted> | |
| 3 | ||
| 4 | Virtual memory map with 4 level page tables: | |
| 5 | ||
| 57d30772 | 6 | 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm |
| 1da177e4 | 7 | hole caused by [48:63] sign extension |
| 57d30772 | 8 | ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole |
| 2feceeff | 9 | ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory |
| c898faf9 RR |
10 | ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole |
| 11 | ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space | |
| 12 | ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole | |
| 13 | ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) | |
| 1da177e4 | 14 | ... unused hole ... |
| cca7c085 | 15 | ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 |
| aca91bfc BP |
16 | ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space |
| 17 | ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls | |
| 18 | ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole | |
| 1da177e4 | 19 | |
| 57d30772 | 20 | The direct mapping covers all memory in the system up to the highest |
| 8315eca2 | 21 | memory address (this means in some cases it can also include PCI memory |
| 57d30772 | 22 | holes). |
| 8315eca2 | 23 | |
| 1da177e4 LT |
24 | vmalloc space is lazily synchronized into the different PML4 pages of |
| 25 | the processes using the page fault handler, with init_level4_pgt as | |
| 26 | reference. | |
| 27 | ||
| 57d30772 RD |
28 | Current X86-64 implementations only support 40 bits of address space, |
| 29 | but we support up to 46 bits. This expands into MBZ space in the page tables. | |
| 1da177e4 LT |
30 | |
| 31 | -Andi Kleen, Jul 2004 |