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Diffstat (limited to 'Documentation/arm64/memory.txt')
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diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt deleted file mode 100644 index 78a377124ef0..000000000000 --- a/Documentation/arm64/memory.txt +++ /dev/null @@ -1,82 +0,0 @@ - Memory Layout on AArch64 Linux - ============================== - -Author: Catalin Marinas <catalin.marinas@arm.com> -Date : 20 February 2012 - -This document describes the virtual memory layout used by the AArch64 -Linux kernel. The architecture allows up to 4 levels of translation -tables with a 4KB page size and up to 3 levels with a 64KB page size. - -AArch64 Linux uses 3 levels of translation tables with the 4KB page -configuration, allowing 39-bit (512GB) virtual addresses for both user -and kernel. With 64KB pages, only 2 levels of translation tables are -used but the memory layout is the same. - -User addresses have bits 63:39 set to 0 while the kernel addresses have -the same bits set to 1. TTBRx selection is given by bit 63 of the -virtual address. The swapper_pg_dir contains only kernel (global) -mappings while the user pgd contains only user (non-global) mappings. -The swapper_pgd_dir address is written to TTBR1 and never written to -TTBR0. - - -AArch64 Linux memory layout: - -Start End Size Use ------------------------------------------------------------------------ -0000000000000000 0000007fffffffff 512GB user - -ffffff8000000000 ffffffbbfffeffff ~240GB vmalloc - -ffffffbbffff0000 ffffffbbffffffff 64KB [guard page] - -ffffffbc00000000 ffffffbdffffffff 8GB vmemmap - -ffffffbe00000000 ffffffbffbbfffff ~8GB [guard, future vmmemap] - -ffffffbffbc00000 ffffffbffbdfffff 2MB earlyprintk device - -ffffffbffbe00000 ffffffbffbe0ffff 64KB PCI I/O space - -ffffffbbffff0000 ffffffbcffffffff ~2MB [guard] - -ffffffbffc000000 ffffffbfffffffff 64MB modules - -ffffffc000000000 ffffffffffffffff 256GB kernel logical memory map - - -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 (not used) - +-------------------------------------------------> [63] 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 (only 38:29 used) - | +-------------------------------> [47:42] L1 index (not used) - +-------------------------------------------------> [63] TTBR0/1 - -When using KVM, the hypervisor maps kernel pages in EL2, at a fixed -offset from the kernel VA (top 24bits of the kernel VA set to zero): - -Start End Size Use ------------------------------------------------------------------------ -0000004000000000 0000007fffffffff 256GB kernel objects mapped in HYP |