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 - ffff80ffffffffff (=40 bits) guard hole 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 ... 15ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks 16... unused hole ... 17ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 18ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space 19ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls 20ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole 21 22The direct mapping covers all memory in the system up to the highest 23memory address (this means in some cases it can also include PCI memory 24holes). 25 26vmalloc space is lazily synchronized into the different PML4 pages of 27the processes using the page fault handler, with init_level4_pgt as 28reference. 29 30Current X86-64 implementations only support 40 bits of address space, 31but we support up to 46 bits. This expands into MBZ space in the page tables. 32 33-Andi Kleen, Jul 2004 34