Environment:Alibaba MNN CPU Build Environment

Field	Value
Environment Name	CPU_Build_Environment
Knowledge Sources	MNN repository: `CMakeLists.txt`, `docs/compile/cmake.md`, `docs/compile/engine.md`
Domain	Infrastructure
Description	Base CPU compilation environment for building MNN core library and tools
Last Updated	2026-02-10

Overview

Base CPU compilation environment for building the MNN core library and tools. This environment defines the minimum toolchain requirements for a successful source build of MNN on desktop platforms. It requires CMake 3.6+, a C++11-compatible compiler (GCC 4.9+ or Clang), and C99 support. All GPU, mobile, and accelerator backends have their own environment pages; this page covers only the CPU-only base build.

System Requirements

Component	Requirement	Notes
Operating System	Linux, macOS, Windows (MSVC or MinGW)	All three platforms are supported as first-class build targets
CMake	>= 3.6 (3.10 recommended, 3.13 for Windows)	`cmake_minimum_required(VERSION 3.6)` declared at `CMakeLists.txt:L1`
C++ Compiler	GCC >= 4.9, Clang, or MSVC >= 2017	Must support C++11 at minimum
C++ Standard	C++11 (default), C++17 optional	`set(CMAKE_CXX_STANDARD 11)` at `CMakeLists.txt:L24`; C++17 enabled when CUDA transformer fuse is active
C Standard	C99	`set(CMAKE_C_STANDARD 99)` at `CMakeLists.txt:L22`
Disk Space	~500MB for build artifacts	Varies with enabled options; converter and protobuf add significant output

Dependencies

Required (System)

cmake >= 3.6 -- Build system generator
gcc >= 4.9 or clang -- C/C++ compiler with C99 and C++11 support
make or ninja -- Build executor (Ninja recommended on Windows)

Optional

protobuf 3.0+ -- Required for TensorFlow and Caffe converter backends. Can use MNN's bundled copy by setting -DMNN_BUILD_PROTOBUFFER=ON (the default).
flatbuffers -- Schema compiler for MNN model format. Bundled in 3rd_party/flatbuffers; no system install needed.

Credentials

None required for base build. The MNN repository is publicly available and all dependencies are either bundled or available through standard package managers.

Quick Install

Linux / macOS

# Linux/macOS
mkdir build && cd build
cmake .. -DMNN_BUILD_CONVERTER=ON -DMNN_BUILD_QUANTOOLS=ON
make -j8

Windows (MSVC)

# Windows (MSVC)
mkdir build && cd build
cmake -G Ninja -DCMAKE_BUILD_TYPE=Release ..
ninja

Code Evidence from CMakeLists.txt

The following excerpts from the root CMakeLists.txt document the environment constraints:

# Line 1: Minimum CMake version
cmake_minimum_required(VERSION 3.6)

# Line 20: Project declaration with C, C++, and ASM languages
project(MNN VERSION ${MNN_VERSION} LANGUAGES C CXX ASM)

# Lines 22-24: Language standard requirements
set(CMAKE_C_STANDARD 99)
set(CMAKE_CXX_STANDARD 11)
# or, when MNN_CUDA and MNN_CUDA_QUANT are both ON:
set(CMAKE_CXX_STANDARD 17)

# Lines 31-36: Windows-specific MSVC checks
if(MSVC)
  # MSVC-specific configuration and runtime flags
  # MNN_SEP_BUILD forced OFF on Windows
endif()

# Lines 196-205: Protobuf build configuration
option(MNN_BUILD_PROTOBUFFER "Build with protobuffer in MNN" ON)
# When ON, builds protobuf from 3rd_party/protobuf/cmake

Common Errors

Error Message	Cause	Solution
`Could NOT find Protobuf`	System protobuf not installed and built-in not enabled	Use `-DMNN_BUILD_PROTOBUFFER=ON` to build protobuf from MNN's bundled sources
`Unrecognized syntax "proto3"`	System protobuf version is too old (pre-3.0)	Upgrade to protobuf 3.0+ or use the built-in protobuf with `-DMNN_BUILD_PROTOBUFFER=ON`
`CMake Error: Could not find CMAKE_ROOT`	CMake is not installed properly or not on PATH	Install CMake via `sudo apt install cmake extra-cmake-modules` or download from cmake.org

Compatibility Notes

Windows: MNN_SEP_BUILD is forced to OFF on Windows regardless of user setting, because the separated backend build model is not supported on that platform.
macOS + Framework: MNN_SEP_BUILD and MNN_AAPL_FMWK cannot coexist. Enabling Apple Framework output requires MNN_SEP_BUILD=OFF.
Static library linking: When linking against a static MNN build, whole-archive flags are required to prevent the linker from stripping unreferenced backend registration symbols:
- GCC / Linux: -Wl,--whole-archive libMNN.a -Wl,--no-whole-archive
- macOS: -Wl,-force_load,libMNN.a
- MSVC: /WHOLEARCHIVE:MNN.lib

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