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- <previous description obsolete, deleted>
- Virtual memory map with 4 level page tables:
- 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
- hole caused by [48:63] sign extension
- ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor
- ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
- ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
- ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space
- ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole
- ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB)
- ... unused hole ...
- ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
- ... unused hole ...
- ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
- ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space
- ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
- ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
- The direct mapping covers all memory in the system up to the highest
- memory address (this means in some cases it can also include PCI memory
- holes).
- 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 bits of address space,
- but we support up to 46 bits. This expands into MBZ space in the page tables.
- ->trampoline_pgd:
- We map EFI runtime services in the aforementioned PGD in the virtual
- range of 64Gb (arbitrarily set, can be raised if needed)
- 0xffffffef00000000 - 0xffffffff00000000
- -Andi Kleen, Jul 2004
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