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authorPalmer Dabbelt <palmer@rivosinc.com>2022-01-20 06:23:41 +0300
committerPalmer Dabbelt <palmer@rivosinc.com>2022-01-20 06:37:44 +0300
commit0c34e79e52bb13881c08f1a2c2390b7b88ff10c7 (patch)
treee8caa54b625f2364cee088c37c088de1d28a32b8 /Documentation
parentfc839c6d33c8828514f595822f457e51328507e5 (diff)
parentc774de22c430733487f70d755067d9ea55dbe6de (diff)
downloadlinux-0c34e79e52bb13881c08f1a2c2390b7b88ff10c7.tar.xz
RISC-V: Introduce sv48 support without relocatable kernel
This patchset allows to have a single kernel for sv39 and sv48 without being relocatable. The idea comes from Arnd Bergmann who suggested to do the same as x86, that is mapping the kernel to the end of the address space, which allows the kernel to be linked at the same address for both sv39 and sv48 and then does not require to be relocated at runtime. This implements sv48 support at runtime. The kernel will try to boot with 4-level page table and will fallback to 3-level if the HW does not support it. Folding the 4th level into a 3-level page table has almost no cost at runtime. Note that kasan region had to be moved to the end of the address space since its location must be known at compile-time and then be valid for both sv39 and sv48 (and sv57 that is coming). * riscv-sv48-v3: riscv: Explicit comment about user virtual address space size riscv: Use pgtable_l4_enabled to output mmu_type in cpuinfo riscv: Implement sv48 support asm-generic: Prepare for riscv use of pud_alloc_one and pud_free riscv: Allow to dynamically define VA_BITS riscv: Introduce functions to switch pt_ops riscv: Split early kasan mapping to prepare sv48 introduction riscv: Move KASAN mapping next to the kernel mapping riscv: Get rid of MAXPHYSMEM configs Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/riscv/vm-layout.rst12
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
index b7f98930d38d..1bd687b97104 100644
--- a/Documentation/riscv/vm-layout.rst
+++ b/Documentation/riscv/vm-layout.rst
@@ -47,12 +47,12 @@ RISC-V Linux Kernel SV39
| Kernel-space virtual memory, shared between all processes:
____________________________________________________________|___________________________________________________________
| | | |
- ffffffc000000000 | -256 GB | ffffffc7ffffffff | 32 GB | kasan
- ffffffcefee00000 | -196 GB | ffffffcefeffffff | 2 MB | fixmap
- ffffffceff000000 | -196 GB | ffffffceffffffff | 16 MB | PCI io
- ffffffcf00000000 | -196 GB | ffffffcfffffffff | 4 GB | vmemmap
- ffffffd000000000 | -192 GB | ffffffdfffffffff | 64 GB | vmalloc/ioremap space
- ffffffe000000000 | -128 GB | ffffffff7fffffff | 124 GB | direct mapping of all physical memory
+ 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
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