From 06267eb2decaa6baac81bbd882265a8e7782dba4 Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Thu, 28 Jul 2022 14:07:15 -0700 Subject: doc: RISC-V: Document that misaligned accesses are supported The RISC-V ISA manual used to mandate that misaligned accesses were supported in user mode, but that requirement was removed in 2018 via riscv-isa-manual commit 61cadb9 ("Provide new description of misaligned load/store behavior compatible with privileged architecture."). Since the Linux uABI was already frozen at that point it's just been demoted to part of the uABI, but that was never written down. Link: https://lore.kernel.org/r/20220728210715.17214-1-palmer@rivosinc.com Signed-off-by: Palmer Dabbelt --- Documentation/riscv/index.rst | 1 + Documentation/riscv/uabi.rst | 6 ++++++ 2 files changed, 7 insertions(+) create mode 100644 Documentation/riscv/uabi.rst (limited to 'Documentation/riscv') diff --git a/Documentation/riscv/index.rst b/Documentation/riscv/index.rst index e23b876ad6eb..2e5b18fbb145 100644 --- a/Documentation/riscv/index.rst +++ b/Documentation/riscv/index.rst @@ -8,6 +8,7 @@ RISC-V architecture boot-image-header vm-layout patch-acceptance + uabi features diff --git a/Documentation/riscv/uabi.rst b/Documentation/riscv/uabi.rst new file mode 100644 index 000000000000..21a82cfb6c4d --- /dev/null +++ b/Documentation/riscv/uabi.rst @@ -0,0 +1,6 @@ +.. SPDX-License-Identifier: GPL-2.0 + +RISC-V Linux User ABI +===================== + +Misaligned accesses are supported in userspace, but they may perform poorly. -- cgit v1.2.3