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 |
beb9147e | 8 | ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor |
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) | |
ef7f0d6a AR |
14 | ... unused hole ... |
15 | ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB) | |
1da177e4 | 16 | ... unused hole ... |
3891a04a PA |
17 | ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks |
18 | ... unused hole ... | |
ff3d0a12 MF |
19 | ffffffef00000000 - ffffffff00000000 (=64 GB) EFI region mapping space |
20 | ... unused hole ... | |
cca7c085 | 21 | ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 |
78b0634d | 22 | ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space |
aca91bfc BP |
23 | ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls |
24 | ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole | |
1da177e4 | 25 | |
57d30772 | 26 | The direct mapping covers all memory in the system up to the highest |
8315eca2 | 27 | memory address (this means in some cases it can also include PCI memory |
57d30772 | 28 | holes). |
8315eca2 | 29 | |
1da177e4 LT |
30 | vmalloc space is lazily synchronized into the different PML4 pages of |
31 | the processes using the page fault handler, with init_level4_pgt as | |
32 | reference. | |
33 | ||
78b0634d JG |
34 | Current X86-64 implementations support up to 46 bits of address space (64 TB), |
35 | which is our current limit. This expands into MBZ space in the page tables. | |
1da177e4 | 36 | |
ff3d0a12 MF |
37 | We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual |
38 | memory window (this size is arbitrary, it can be raised later if needed). | |
39 | The mappings are not part of any other kernel PGD and are only available | |
40 | during EFI runtime calls. | |
d2f7cbe7 | 41 | |
1da177e4 | 42 | -Andi Kleen, Jul 2004 |