| |
| <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 ... |
| ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB) |
| ... 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 |
