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Diffstat (limited to 'Documentation/x86_64/mm.txt')
| -rw-r--r-- | Documentation/x86_64/mm.txt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/x86_64/mm.txt b/Documentation/x86_64/mm.txt new file mode 100644 index 00000000000..662b73971a6 --- /dev/null +++ b/Documentation/x86_64/mm.txt @@ -0,0 +1,24 @@ + +<previous description obsolete, deleted> + +Virtual memory map with 4 level page tables: + +0000000000000000 - 00007fffffffffff (=47bits) user space, different per mm +hole caused by [48:63] sign extension +ffff800000000000 - ffff80ffffffffff (=40bits) guard hole +ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of phys. memory +ffffc10000000000 - ffffc1ffffffffff (=40bits) hole +ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space +... unused hole ... +ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0 +... unused hole ... +ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space + +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 bit of address space, +but we support upto 46bits. This expands into MBZ space in the page tables. + +-Andi Kleen, Jul 2004 |