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diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst deleted file mode 100644 index 1bd687b97104..000000000000 --- a/Documentation/riscv/vm-layout.rst +++ /dev/null @@ -1,63 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -===================================== -Virtual Memory Layout on RISC-V Linux -===================================== - -:Author: Alexandre Ghiti <alex@ghiti.fr> -:Date: 12 February 2021 - -This document describes the virtual memory layout used by the RISC-V Linux -Kernel. - -RISC-V Linux Kernel 32bit -========================= - -RISC-V Linux Kernel SV32 ------------------------- - -TODO - -RISC-V Linux Kernel 64bit -========================= - -The RISC-V privileged architecture document states that the 64bit addresses -"must have bits 63–48 all equal to bit 47, or else a page-fault exception will -occur.": that splits the virtual address space into 2 halves separated by a very -big hole, the lower half is where the userspace resides, the upper half is where -the RISC-V Linux Kernel resides. - -RISC-V Linux Kernel SV39 ------------------------- - -:: - - ======================================================================================================================== - Start addr | Offset | End addr | Size | VM area description - ======================================================================================================================== - | | | | - 0000000000000000 | 0 | 0000003fffffffff | 256 GB | user-space virtual memory, different per mm - __________________|____________|__________________|_________|___________________________________________________________ - | | | | - 0000004000000000 | +256 GB | ffffffbfffffffff | ~16M TB | ... huge, almost 64 bits wide hole of non-canonical - | | | | virtual memory addresses up to the -256 GB - | | | | starting offset of kernel mappings. - __________________|____________|__________________|_________|___________________________________________________________ - | - | Kernel-space virtual memory, shared between all processes: - ____________________________________________________________|___________________________________________________________ - | | | | - ffffffc6fee00000 | -228 GB | ffffffc6feffffff | 2 MB | fixmap - ffffffc6ff000000 | -228 GB | ffffffc6ffffffff | 16 MB | PCI io - ffffffc700000000 | -228 GB | ffffffc7ffffffff | 4 GB | vmemmap - ffffffc800000000 | -224 GB | ffffffd7ffffffff | 64 GB | vmalloc/ioremap space - ffffffd800000000 | -160 GB | fffffff6ffffffff | 124 GB | direct mapping of all physical memory - fffffff700000000 | -36 GB | fffffffeffffffff | 32 GB | kasan - __________________|____________|__________________|_________|____________________________________________________________ - | - | - ____________________________________________________________|____________________________________________________________ - | | | | - ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF - ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel - __________________|____________|__________________|_________|____________________________________________________________ |