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 ... 15ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0 16ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space 17 18The direct mapping covers all memory in the system up to the highest 19memory address (this means in some cases it can also include PCI memory 20holes). 21 22vmalloc space is lazily synchronized into the different PML4 pages of 23the processes using the page fault handler, with init_level4_pgt as 24reference. 25 26Current X86-64 implementations only support 40 bits of address space, 27but we support up to 46 bits. This expands into MBZ space in the page tables. 28 29-Andi Kleen, Jul 2004 30