[v2,08/10] Documentation: riscv: Add sv48 description to VM layout

Commit Message

Alexandre Ghiti Sept. 29, 2021, 2:51 p.m. UTC

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

Signed-off-by: Alexandre Ghiti <[e-mail]>
---
 Documentation/riscv/vm-layout.rst | 36 +++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

Patch

diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
index b7f98930d38d..f10128e0a95f 100644
--- a/Documentation/riscv/vm-layout.rst
+++ b/Documentation/riscv/vm-layout.rst
@@ -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:
+  ____________________________________________________________|___________________________________________________________
+                    |            |                  |         |
+   ffff800000000000 | -128    TB | ffff8fffffffffff |   16 TB | kasan
+   ffff9dfffee00000 |  -94    TB | ffff9dfffeffffff |    2 MB | fixmap
+   ffff9dffff000000 |  -94    TB | ffff9dffffffffff |   16 MB | PCI io
+   ffff9e0000000000 |  -94    TB | ffff9fffffffffff |    2 TB | vmemmap
+   ffffa00000000000 |  -92    TB | ffffbfffffffffff |   32 TB | vmalloc/ioremap space
+   ffffc00000000000 |  -64    TB | fffffffeffffffff |   64 TB | direct mapping of all physical memory
+  __________________|____________|__________________|_________|____________________________________________________________
+                                                              |
+                                                              | 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
+  __________________|____________|__________________|_________|____________________________________________________________