diff options
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/x86_64/mm.txt | 24 |
1 files changed, 11 insertions, 13 deletions
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt index 3448e675b462..51101708a03a 100644 --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -1,6 +1,4 @@ -<previous description obsolete, deleted> - Virtual memory map with 4 level page tables: 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm @@ -14,13 +12,15 @@ ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) ... unused hole ... ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB) ... unused hole ... +fffffe8000000000 - fffffeffffffffff (=39 bits) cpu_entry_area mapping ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks ... unused hole ... ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space ... unused hole ... ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0 -ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space (variable) -ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls +ffffffffa0000000 - [fixmap start] (~1526 MB) module mapping space (variable) +[fixmap start] - ffffffffff5fffff kernel-internal fixmap range +ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole Virtual memory map with 5 level page tables: @@ -36,19 +36,22 @@ ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB) ... unused hole ... ffdf000000000000 - fffffc0000000000 (=53 bits) kasan shadow memory (8PB) ... unused hole ... +fffffe8000000000 - fffffeffffffffff (=39 bits) cpu_entry_area mapping ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks ... unused hole ... ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space ... unused hole ... ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0 -ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space -ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls +ffffffffa0000000 - [fixmap start] (~1526 MB) module mapping space +[fixmap start] - ffffffffff5fffff kernel-internal fixmap range +ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole Architecture defines a 64-bit virtual address. Implementations can support less. Currently supported are 48- and 57-bit virtual addresses. Bits 63 -through to the most-significant implemented bit are set to either all ones -or all zero. This causes hole between user space and kernel addresses. +through to the most-significant implemented bit are sign extended. +This causes hole between user space and kernel addresses if you interpret them +as unsigned. 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 @@ -58,9 +61,6 @@ vmalloc space is lazily synchronized into the different PML4/PML5 pages of the processes using the page fault handler, with init_top_pgt as reference. -Current X86-64 implementations support up to 46 bits of address space (64 TB), -which is our current limit. This expands into MBZ space in the page tables. - We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual memory window (this size is arbitrary, it can be raised later if needed). The mappings are not part of any other kernel PGD and are only available @@ -72,5 +72,3 @@ following fixmap section. Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all physical memory, vmalloc/ioremap space and virtual memory map are randomized. Their order is preserved but their base will be offset early at boot time. - --Andi Kleen, Jul 2004 |