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

Alexandre Ghiti
2021-09-29T14:59:53Z

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

Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
---
Documentation/riscv/vm-layout.rst | 36 +++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

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
+ __________________|____________|__________________|_________|____________________________________________________________
--
2.30.2