Unverified Commit 9d19f2b5 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
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Documentation: riscv: Add sv48 description to VM layout 



sv48 was just introduced, so add its virtual memory layout to the
documentation.

Signed-off-by: default avatarAlexandre Ghiti <alexandre.ghiti@canonical.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 77d707a3

Documentation/riscv/vm-layout.rst

+36 −0
Original line number Diff line number Diff line
@@ -61,3 +61,39 @@ RISC-V Linux Kernel SV39 
   ffffffff00000000 |   -4    GB | ffffffff7fffffff |    2 GB | modules, BPF

   ffffffff80000000 |   -2    GB | ffffffffffffffff |    2 GB | kernel

  __________________|____________|__________________|_________|____________________________________________________________





RISC-V Linux Kernel SV48

------------------------



::



 ========================================================================================================================

      Start addr    |   Offset   |     End addr     |  Size   | VM area description

 ========================================================================================================================

                    |            |                  |         |

   0000000000000000 |    0       | 00007fffffffffff |  128 TB | user-space virtual memory, different per mm

  __________________|____________|__________________|_________|___________________________________________________________

                    |            |                  |         |

   0000800000000000 | +128    TB | ffff7fffffffffff | ~16M TB | ... huge, almost 64 bits wide hole of non-canonical

                    |            |                  |         | virtual memory addresses up to the -128 TB

                    |            |                  |         | starting offset of kernel mappings.

  __________________|____________|__________________|_________|___________________________________________________________

                                                              |

                                                              | Kernel-space virtual memory, shared between all processes:

  ____________________________________________________________|___________________________________________________________

                    |            |                  |         |

   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 | direct mapping of all physical memory

   ffffef8000000000 |  -16.5  TB | fffffffeffffffff | 16.5 TB | kasan

  __________________|____________|__________________|_________|____________________________________________________________

                                                              |

                                                              | Identical layout to the 39-bit one from here on:

  ____________________________________________________________|____________________________________________________________

                    |            |                  |         |

   ffffffff00000000 |   -4    GB | ffffffff7fffffff |    2 GB | modules, BPF

   ffffffff80000000 |   -2    GB | ffffffffffffffff |    2 GB | kernel

  __________________|____________|__________________|_________|____________________________________________________________