1 2<previous description obsolete, deleted> 3 4Virtual memory map with 4 level page tables: 5 60000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm 7hole caused by [48:63] sign extension 8ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor 9ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory 10ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole 11ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space 12ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole 13ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) 14... unused hole ... 15ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB) 16... unused hole ... 17ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks 18... unused hole ... 19ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 20ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space 21ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls 22ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole 23 24The direct mapping covers all memory in the system up to the highest 25memory address (this means in some cases it can also include PCI memory 26holes). 27 28vmalloc space is lazily synchronized into the different PML4 pages of 29the processes using the page fault handler, with init_level4_pgt as 30reference. 31 32Current X86-64 implementations only support 40 bits of address space, 33but we support up to 46 bits. This expands into MBZ space in the page tables. 34 35->trampoline_pgd: 36 37We map EFI runtime services in the aforementioned PGD in the virtual 38range of 64Gb (arbitrarily set, can be raised if needed) 39 400xffffffef00000000 - 0xffffffff00000000 41 42-Andi Kleen, Jul 2004 43