Implementation:NVIDIA DALI CMake Plugin Build

Knowledge Sources	NVIDIA DALI
Domains	Custom_Operators, Build_Systems, CMake
Last Updated	2026-02-08 00:00 GMT

Overview

Concrete CMake build configuration provided by the NVIDIA DALI NaiveHistogram example for compiling a custom operator plugin into a shared library (libnaivehistogram.so) that links against the installed DALI package.

Description

The CMakeLists.txt for the NaiveHistogram plugin is the reference build configuration for custom DALI operators. It performs the following steps:

1. Sets the minimum CMake version to 3.25.2 and targets CUDA architectures 80 (Ampere) and 90 (Hopper).
2. Declares the project with CUDA, CXX, and C language support.
3. Enforces C++20 and CUDA 20 standards.
4. Adds CUDA toolkit include directories via CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES.
5. Discovers DALI's library directory by running python -c "import nvidia.dali as dali; print(dali.sysconfig.get_lib_dir())" and stores it in DALI_LIB_DIR.
6. Discovers DALI's compile flags by running python -c "import nvidia.dali as dali; print(' '.join(dali.sysconfig.get_compile_flags()))" and appends them to CMAKE_CXX_FLAGS and CMAKE_CUDA_FLAGS.
7. Adds DALI_LIB_DIR to the linker search path via link_directories().
8. Defines PLUGIN_SOURCES as the list of .cc and .cu files.
9. Creates the shared library target naivehistogram and links it against dali.

Usage

To build the plugin:

cd docs/examples/custom_operations/custom_operator/naive_histogram
cmake -B build
cmake --build build

The resulting libnaivehistogram.so will be in the build/ directory.

Code Reference

Source Location

• Repository: NVIDIA DALI
• File: docs/examples/custom_operations/custom_operator/naive_histogram/CMakeLists.txt (lines 1-37)

Signature

cmake_minimum_required(VERSION 3.25.2)
set(CMAKE_CUDA_ARCHITECTURES "80;90")

project(naive_histogram_plugin LANGUAGES CUDA CXX C)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_C_STANDARD 11)

set(CMAKE_CUDA_STANDARD 20)
set(CMAKE_CUDA_STANDARD_REQUIRED ON)

add_library(naivehistogram SHARED ${PLUGIN_SOURCES})
target_link_libraries(naivehistogram dali)

Import

# No import needed; this is a standalone CMake configuration file.
# Dependencies are resolved at configure time via Python introspection:
execute_process(
        COMMAND python -c "import nvidia.dali as dali; print(dali.sysconfig.get_lib_dir())"
        OUTPUT_VARIABLE DALI_LIB_DIR)

I/O Contract

Inputs

Name	Type	Required	Description
PLUGIN_SOURCES	CMake variable (list of file paths)	Yes	List of C++ and CUDA source files to compile. In the example: naive_histogram.cc and naive_histogram.cu.
CMAKE_CUDA_ARCHITECTURES	CMake variable (string)	Yes	Semicolon-separated list of CUDA compute capabilities to target (e.g., "80;90").
nvidia.dali (Python package)	Installed package	Yes	Must be importable by Python at configure time. Provides sysconfig.get_lib_dir() and sysconfig.get_compile_flags().
CUDA toolkit	System installation	Yes	Provides nvcc compiler and CUDA runtime headers via CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES.

Outputs

Name	Type	Description
libnaivehistogram.so	Shared library file	Dynamically loadable plugin containing the compiled operator. Contains self-registering static initializers for the operator schema and factory.

Usage Examples

Example: Complete CMakeLists.txt

cmake_minimum_required(VERSION 3.25.2)
set(CMAKE_CUDA_ARCHITECTURES "80;90")

project(naive_histogram_plugin LANGUAGES CUDA CXX C)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_C_STANDARD 11)

set(CMAKE_CUDA_STANDARD 20)
set(CMAKE_CUDA_STANDARD_REQUIRED ON)

include_directories(SYSTEM "${CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES}")

execute_process(
        COMMAND python -c "import nvidia.dali as dali; print(dali.sysconfig.get_lib_dir())"
        OUTPUT_VARIABLE DALI_LIB_DIR)
string(STRIP ${DALI_LIB_DIR} DALI_LIB_DIR)

execute_process(
        COMMAND python -c "import nvidia.dali as dali; print(\" \".join(dali.sysconfig.get_compile_flags()))"
        OUTPUT_VARIABLE DALI_COMPILE_FLAGS)
string(STRIP ${DALI_COMPILE_FLAGS} DALI_COMPILE_FLAGS)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${DALI_COMPILE_FLAGS} ")
set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} ${DALI_COMPILE_FLAGS} ")
link_directories("${DALI_LIB_DIR}")

set(PLUGIN_SOURCES
        ${CMAKE_CURRENT_SOURCE_DIR}/naive_histogram.cc
        ${CMAKE_CURRENT_SOURCE_DIR}/naive_histogram.cu
        )

add_library(naivehistogram SHARED ${PLUGIN_SOURCES})
target_link_libraries(naivehistogram dali)

Related Pages

Implements Principle

• Principle:NVIDIA_DALI_Custom_Operator_Build_System

Requires Environment

• Environment:NVIDIA_DALI_CMake_Build_Environment