diff options
| author | Charlie Jenkins <charlie@rivosinc.com> | 2024-08-26 09:36:45 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-08-29 06:03:24 -0700 |
| commit | 954260ff5a4657eb97ad7e1618505074f1610acc (patch) | |
| tree | b2247f170cd07f909c1f9c9c2b3530553f67ae87 /Documentation/arch/riscv | |
| parent | 8400291e289ee6b2bf9779ff1c83a291501f017b (diff) | |
Revert "RISC-V: mm: Document mmap changes"
This mmap behavior caused unintended breakages so the behavior has been
changed.
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20240826-riscv_mmap-v1-1-cd8962afe47f@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'Documentation/arch/riscv')
| -rw-r--r-- | Documentation/arch/riscv/vm-layout.rst | 16 |
1 files changed, 0 insertions, 16 deletions
diff --git a/Documentation/arch/riscv/vm-layout.rst b/Documentation/arch/riscv/vm-layout.rst index 077b968dcc81..eabec99b5852 100644 --- a/Documentation/arch/riscv/vm-layout.rst +++ b/Documentation/arch/riscv/vm-layout.rst @@ -134,19 +134,3 @@ RISC-V Linux Kernel SV57 ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel __________________|____________|__________________|_________|____________________________________________________________ - - -Userspace VAs --------------------- -To maintain compatibility with software that relies on the VA space with a -maximum of 48 bits the kernel will, by default, return virtual addresses to -userspace from a 48-bit range (sv48). This default behavior is achieved by -passing 0 into the hint address parameter of mmap. On CPUs with an address space -smaller than sv48, the CPU maximum supported address space will be the default. - -Software can "opt-in" to receiving VAs from another VA space by providing -a hint address to mmap. When a hint address is passed to mmap, the returned -address will never use more bits than the hint address. For example, if a hint -address of `1 << 40` is passed to mmap, a valid returned address will never use -bits 41 through 63. If no mappable addresses are available in that range, mmap -will return `MAP_FAILED`. |