linux-kernel - [PATCH 1/3] Revert "RISC-V: mm: Document mmap changes"

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Message-Id: <20240826-riscv_mmap-v1-1-cd8962afe47f@rivosinc.com>
Date: Mon, 26 Aug 2024 09:36:45 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Jonathan Corbet <corbet@....net>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Shuah Khan <shuah@...nel.org>, Yangyu Chen <cyy@...self.name>, 
 Levi Zim <rsworktech@...look.com>, Alexandre Ghiti <alexghiti@...osinc.com>
Cc: linux-doc@...r.kernel.org, linux-riscv@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Palmer Dabbelt <palmer@...osinc.com>, 
 linux-kselftest@...r.kernel.org, Charlie Jenkins <charlie@...osinc.com>
Subject: [PATCH 1/3] 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@...osinc.com>
---
 Documentation/arch/riscv/vm-layout.rst | 16 ----------------
 1 file changed, 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`.

-- 
2.45.0