.. SPDX-License-Identifier: GPL-2.0
.. include:: ../../disclaimer-zh_CN.rst

:Original: Documentation/arch/riscv/vm-layout.rst

:翻译:

 司延腾 Yanteng Si <siyanteng@loongson.cn>
        Binbin Zhou <zhoubinbin@loongson.cn>

============================
RISC-V Linux上的虚拟内存布局
============================

:作者: Alexandre Ghiti <alex@ghiti.fr>
:日期: 12 February 2021

这份文件描述了RISC-V Linux内核使用的虚拟内存布局。

32位 RISC-V Linux 内核
======================

RISC-V Linux Kernel SV32
------------------------

TODO

64位 RISC-V Linux 内核
======================

RISC-V特权架构文档指出，64位地址 "必须使第63-48位值都等于第47位，否则将发生缺页异常。"：这将虚
拟地址空间分成两半，中间有一个非常大的洞，下半部分是用户空间所在的地方，上半部分是RISC-V Linux
内核所在的地方。

RISC-V Linux Kernel SV39
------------------------

::

  ========================================================================================================================
      开始地址       |   偏移      |     结束地址      |  大小    | 虚拟内存区域描述
  ========================================================================================================================
                    |            |                  |         |
   0000000000000000 |    0       | 0000003fffffffff |  256 GB | 用户空间虚拟内存，每个内存管理器不同
  __________________|____________|__________________|_________|___________________________________________________________
                    |            |                  |         |
   0000004000000000 | +256    GB | ffffffbfffffffff | ~16M TB | ... 巨大的、几乎64位宽的直到内核映射的-256GB地方
                    |            |                  |         |     开始偏移的非经典虚拟内存地址空洞。
                    |            |                  |         |
  __________________|____________|__________________|_________|___________________________________________________________
                                                              |
                                                              | 内核空间的虚拟内存，在所有进程之间共享:
  ____________________________________________________________|___________________________________________________________
                    |            |                  |         |
   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 | 直接映射所有物理内存
   fffffff700000000 |  -36    GB | fffffffeffffffff |   32 GB | kasan
  __________________|____________|__________________|_________|____________________________________________________________
                                                              |
                                                              |
  ____________________________________________________________|____________________________________________________________
                    |            |                  |         |
   ffffffff00000000 |   -4    GB | ffffffff7fffffff |    2 GB | modules, BPF
   ffffffff80000000 |   -2    GB | ffffffffffffffff |    2 GB | kernel
  __________________|____________|__________________|_________|____________________________________________________________


RISC-V Linux Kernel SV48
------------------------

::

 ========================================================================================================================
      开始地址       |   偏移      |     结束地址      |  大小    | 虚拟内存区域描述
 ========================================================================================================================
                    |            |                  |         |
   0000000000000000 |    0       | 00007fffffffffff |  128 TB | 用户空间虚拟内存，每个内存管理器不同
  __________________|____________|__________________|_________|___________________________________________________________
                    |            |                  |         |
   0000800000000000 | +128    TB | ffff7fffffffffff | ~16M TB | ... 巨大的、几乎64位宽的直到内核映射的-128TB地方
                    |            |                  |         |     开始偏移的非经典虚拟内存地址空洞。
                    |            |                  |         |
  __________________|____________|__________________|_________|___________________________________________________________
                                                              |
                                                              | 内核空间的虚拟内存，在所有进程之间共享:
  ____________________________________________________________|___________________________________________________________
                    |            |                  |         |
   ffff8d7ffee00000 |  -114.5 TB | ffff8d7ffeffffff |    2 MB | fixmap
   ffff8d7fff000000 |  -114.5 TB | ffff8d7fffffffff |   16 MB | PCI io
   ffff8d8000000000 |  -114.5 TB | ffff8f7fffffffff |    2 TB | vmemmap
   ffff8f8000000000 |  -112.5 TB | ffffaf7fffffffff |   32 TB | vmalloc/ioremap space
   ffffaf8000000000 |  -80.5  TB | ffffef7fffffffff |   64 TB | 直接映射所有物理内存
   ffffef8000000000 |  -16.5  TB | fffffffeffffffff | 16.5 TB | kasan
  __________________|____________|__________________|_________|____________________________________________________________
                                                              |
                                                              | 从此处开始，与39-bit布局相同：
  ____________________________________________________________|____________________________________________________________
                    |            |                  |         |
   ffffffff00000000 |   -4    GB | ffffffff7fffffff |    2 GB | modules, BPF
   ffffffff80000000 |   -2    GB | ffffffffffffffff |    2 GB | kernel
  __________________|____________|__________________|_________|____________________________________________________________