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Commit | Line | Data |
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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 RD |
8 | ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole |
9 | ffff810000000000 - ffffc0ffffffffff (=46 bits) direct mapping of all phys. memory | |
10 | ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole | |
11 | ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space | |
0889eba5 | 12 | ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB) |
1da177e4 | 13 | ... unused hole ... |
cca7c085 JS |
14 | ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 |
15 | ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space | |
1da177e4 | 16 | |
57d30772 | 17 | The direct mapping covers all memory in the system up to the highest |
8315eca2 | 18 | memory address (this means in some cases it can also include PCI memory |
57d30772 | 19 | holes). |
8315eca2 | 20 | |
1da177e4 LT |
21 | vmalloc space is lazily synchronized into the different PML4 pages of |
22 | the processes using the page fault handler, with init_level4_pgt as | |
23 | reference. | |
24 | ||
57d30772 RD |
25 | Current X86-64 implementations only support 40 bits of address space, |
26 | but we support up to 46 bits. This expands into MBZ space in the page tables. | |
1da177e4 LT |
27 | |
28 | -Andi Kleen, Jul 2004 |