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 JS |
15 | ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 |
16 | ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space | |
1da177e4 | 17 | |
57d30772 | 18 | The direct mapping covers all memory in the system up to the highest |
8315eca2 | 19 | memory address (this means in some cases it can also include PCI memory |
57d30772 | 20 | holes). |
8315eca2 | 21 | |
1da177e4 LT |
22 | vmalloc space is lazily synchronized into the different PML4 pages of |
23 | the processes using the page fault handler, with init_level4_pgt as | |
24 | reference. | |
25 | ||
57d30772 RD |
26 | Current X86-64 implementations only support 40 bits of address space, |
27 | but we support up to 46 bits. This expands into MBZ space in the page tables. | |
1da177e4 LT |
28 | |
29 | -Andi Kleen, Jul 2004 |