diff options
| author | Will Deacon <will@kernel.org> | 2025-01-13 16:34:00 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-01-13 16:40:30 +0000 |
| commit | fd10f08cb57b891a9bc7cef4ffb26772d91bebf5 (patch) | |
| tree | 1288f3fe71c97e958f0bb5fe3182d70fad67b5c4 | |
| parent | 1e4a5e3679cc4d037982bfc822d939d5ba954e70 (diff) | |
Documentation: arm64: Remove stale and redundant virtual memory diagrams
The arm64 'memory.rst' file tries to document the virtual memory map
and the translation procedure for a couple of kernel configurations.
Unfortunately, the virtual memory map changes relatively frequently and
we support considerably more configurations than we did when the docs
were introduced (e.g. we now have support for 16KiB pages and 52-bit
addressing). Furthermore, the Arm ARM is the definitive resource for the
translation procedure and so there's little point in duplicating part
of that information in the kernel documentation.
Rather than continue trying (and failing) to maintain these diagrams,
let's rip them out. The kernel page-table can be dumped using
CONFIG_PTDUMP_DEBUGFS if necesssary.
Link: https://lore.kernel.org/r/20250102065554.1533781-1-sangmoon.kim@samsung.com
Reported-by: Sangmoon Kim <sangmoon.kim@samsung.com>
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | Documentation/arch/arm64/memory.rst | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/Documentation/arch/arm64/memory.rst b/Documentation/arch/arm64/memory.rst index 8a658984b8bb..678fbb418c3a 100644 --- a/Documentation/arch/arm64/memory.rst +++ b/Documentation/arch/arm64/memory.rst @@ -23,71 +23,6 @@ swapper_pg_dir contains only kernel (global) mappings while the user pgd contains only user (non-global) mappings. The swapper_pg_dir address is written to TTBR1 and never written to TTBR0. - -AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit):: - - Start End Size Use - ----------------------------------------------------------------------- - 0000000000000000 0000ffffffffffff 256TB user - ffff000000000000 ffff7fffffffffff 128TB kernel logical memory map - [ffff600000000000 ffff7fffffffffff] 32TB [kasan shadow region] - ffff800000000000 ffff80007fffffff 2GB modules - ffff800080000000 fffffbffefffffff 124TB vmalloc - fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down) - fffffbfffe000000 fffffbfffe7fffff 8MB [guard region] - fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space - fffffbffff800000 fffffbffffffffff 8MB [guard region] - fffffc0000000000 fffffdffffffffff 2TB vmemmap - fffffe0000000000 ffffffffffffffff 2TB [guard region] - - -AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support):: - - Start End Size Use - ----------------------------------------------------------------------- - 0000000000000000 000fffffffffffff 4PB user - fff0000000000000 ffff7fffffffffff ~4PB kernel logical memory map - [fffd800000000000 ffff7fffffffffff] 512TB [kasan shadow region] - ffff800000000000 ffff80007fffffff 2GB modules - ffff800080000000 fffffbffefffffff 124TB vmalloc - fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down) - fffffbfffe000000 fffffbfffe7fffff 8MB [guard region] - fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space - fffffbffff800000 fffffbffffffffff 8MB [guard region] - fffffc0000000000 ffffffdfffffffff ~4TB vmemmap - ffffffe000000000 ffffffffffffffff 128GB [guard region] - - -Translation table lookup with 4KB pages:: - - +--------+--------+--------+--------+--------+--------+--------+--------+ - |63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0| - +--------+--------+--------+--------+--------+--------+--------+--------+ - | | | | | | - | | | | | v - | | | | | [11:0] in-page offset - | | | | +-> [20:12] L3 index - | | | +-----------> [29:21] L2 index - | | +---------------------> [38:30] L1 index - | +-------------------------------> [47:39] L0 index - +----------------------------------------> [55] TTBR0/1 - - -Translation table lookup with 64KB pages:: - - +--------+--------+--------+--------+--------+--------+--------+--------+ - |63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0| - +--------+--------+--------+--------+--------+--------+--------+--------+ - | | | | | - | | | | v - | | | | [15:0] in-page offset - | | | +----------> [28:16] L3 index - | | +--------------------------> [41:29] L2 index - | +-------------------------------> [47:42] L1 index (48-bit) - | [51:42] L1 index (52-bit) - +----------------------------------------> [55] TTBR0/1 - - When using KVM without the Virtualization Host Extensions, the hypervisor maps kernel pages in EL2 at a fixed (and potentially random) offset from the linear mapping. See the kern_hyp_va macro and |