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Based on kernel version 4.13.3. Page generated on 2017-09-23 13:56 EST.

1	
2	<previous description obsolete, deleted>
3	
4	Virtual memory map with 4 level page tables:
5	
6	0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
7	hole caused by [47:63] sign extension
8	ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor
9	ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
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)
14	... unused hole ...
15	ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)
16	... unused hole ...
17	ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
18	... unused hole ...
19	ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
20	... unused hole ...
21	ffffffff80000000 - ffffffff9fffffff (=512 MB)  kernel text mapping, from phys 0
22	ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space (variable)
23	ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
24	ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
25	
26	Virtual memory map with 5 level page tables:
27	
28	0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm
29	hole caused by [56:63] sign extension
30	ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
31	ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
32	ff90000000000000 - ff91ffffffffffff (=49 bits) hole
33	ff92000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space
34	ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole
35	ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)
36	... unused hole ...
37	ffd8000000000000 - fff7ffffffffffff (=53 bits) kasan shadow memory (8PB)
38	... unused hole ...
39	ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
40	... unused hole ...
41	ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
42	... unused hole ...
43	ffffffff80000000 - ffffffff9fffffff (=512 MB)  kernel text mapping, from phys 0
44	ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space
45	ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
46	ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
47	
48	Architecture defines a 64-bit virtual address. Implementations can support
49	less. Currently supported are 48- and 57-bit virtual addresses. Bits 63
50	through to the most-significant implemented bit are set to either all ones
51	or all zero. This causes hole between user space and kernel addresses.
52	
53	The direct mapping covers all memory in the system up to the highest
54	memory address (this means in some cases it can also include PCI memory
55	holes).
56	
57	vmalloc space is lazily synchronized into the different PML4/PML5 pages of
58	the processes using the page fault handler, with init_top_pgt as
59	reference.
60	
61	Current X86-64 implementations support up to 46 bits of address space (64 TB),
62	which is our current limit. This expands into MBZ space in the page tables.
63	
64	We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
65	memory window (this size is arbitrary, it can be raised later if needed).
66	The mappings are not part of any other kernel PGD and are only available
67	during EFI runtime calls.
68	
69	The module mapping space size changes based on the CONFIG requirements for the
70	following fixmap section.
71	
72	Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
73	physical memory, vmalloc/ioremap space and virtual memory map are randomized.
74	Their order is preserved but their base will be offset early at boot time.
75	
76	-Andi Kleen, Jul 2004
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