2005-04-16 18:20:36 -04:00
|
|
|
|
|
|
|
|
<previous description obsolete, deleted>
|
|
|
|
|
|
|
|
|
|
Virtual memory map with 4 level page tables:
|
|
|
|
|
|
|
|
|
|
0000000000000000 - 00007fffffffffff (=47bits) user space, different per mm
|
|
|
|
|
hole caused by [48:63] sign extension
|
|
|
|
|
ffff800000000000 - ffff80ffffffffff (=40bits) guard hole
|
2005-11-05 11:25:54 -05:00
|
|
|
ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of all phys. memory
|
2005-04-16 18:20:36 -04:00
|
|
|
ffffc10000000000 - ffffc1ffffffffff (=40bits) hole
|
|
|
|
|
ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space
|
|
|
|
|
... unused hole ...
|
|
|
|
|
ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0
|
|
|
|
|
... unused hole ...
|
|
|
|
|
ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space
|
|
|
|
|
|
2005-11-05 11:25:54 -05:00
|
|
|
The direct mapping covers all memory in the system upto the highest
|
|
|
|
|
memory address (this means in some cases it can also include PCI memory
|
|
|
|
|
holes)
|
|
|
|
|
|
2005-04-16 18:20:36 -04:00
|
|
|
vmalloc space is lazily synchronized into the different PML4 pages of
|
|
|
|
|
the processes using the page fault handler, with init_level4_pgt as
|
|
|
|
|
reference.
|
|
|
|
|
|
|
|
|
|
Current X86-64 implementations only support 40 bit of address space,
|
|
|
|
|
but we support upto 46bits. This expands into MBZ space in the page tables.
|
|
|
|
|
|
|
|
|
|
-Andi Kleen, Jul 2004
|
