tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1
2<previous description obsolete, deleted>
3
4Virtual memory map with 4 level page tables:
5
60000000000000000 - 00007fffffffffff (=47bits) user space, different per mm
7hole caused by [48:63] sign extension
8ffff800000000000 - ffff80ffffffffff (=40bits) guard hole
9ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of all phys. memory
10ffffc10000000000 - ffffc1ffffffffff (=40bits) hole
11ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space
12... unused hole ...
13ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0
14... unused hole ...
15ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space
16
17The direct mapping covers all memory in the system upto the highest
18memory address (this means in some cases it can also include PCI memory
19holes)
20
21vmalloc space is lazily synchronized into the different PML4 pages of
22the processes using the page fault handler, with init_level4_pgt as
23reference.
24
25Current X86-64 implementations only support 40 bit of address space,
26but we support upto 46bits. This expands into MBZ space in the page tables.
27
28-Andi Kleen, Jul 2004