From a47b422205a1be173e14ffa216e974b3d8c44a6a Mon Sep 17 00:00:00 2001
From: shawnz <shawnz@nvidia.com>
Date: Wed, 11 Jun 2025 16:32:09 +0800
Subject: [PATCH] Update CHANGELOG.md and README.md for QNX cross build

---
 CHANGELOG.md                                 |  1 +
 README.md                                    | 11 ++++++++---
 cmake/toolchains/toolchain-aarch64-qnx.cmake | 14 ++++++++++++--
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 19cc5391..cb70c6f2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -77,6 +77,7 @@
             * `simpleCUFFT_2d_MGPU`
             * `simpleCUFFT_MGPU`
             * `simpleCUFFT_callback`
+* Updated toolchain for cross-compilation for Tegra QNX platforms.
 
 ### CUDA 12.9
 * Updated toolchain for cross-compilation for Tegra Linux platforms.
diff --git a/README.md b/README.md
index 6c45cca9..e8deb49e 100644
--- a/README.md
+++ b/README.md
@@ -135,9 +135,14 @@ $ cmake -DCMAKE_CUDA_COMPILER=/usr/local/cuda/bin/nvcc -DCMAKE_LIBRARY_PATH=/usr
 
 ### QNX
 
-Note that in the current branch sample cross-compilation for QNX is not fully validated. This placeholder will be updated in the
-near future with QNX cross-compilation instructions. In the meantime, if you want to cross-compile for QNX please check out one
-of the previous tags prior to the CMake build system transition in 12.8.
+The sample cross-compilation for QNX is supported since v13.0 CUDA Samples. An example build for Tegra Thor QNX platform might like this:
+
+```
+$ mkdir build
+$ cd build
+
+QNX_HOST=/path/to/qnx/host QNX_TARGET=/path/to/qnx/target cmake .. -DBUILD_TEGRA=True -DCMAKE_CUDA_COMPILER=/usr/local/cuda-safe-13.0/bin/nvcc -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchains/toolchain-aarch64-qnx.cmake -DCMAKE_LIBRARY_PATH=/usr/local/cuda-safe-13.0/thor/targets/aarch64-qnx/lib/stubs/ -DCMAKE_INCLUDE_PATH=/usr/local/cuda-safe-13.0/thor/targets/aarch64-qnx/include/
+```
 
 ## Running All Samples as Tests
 
diff --git a/cmake/toolchains/toolchain-aarch64-qnx.cmake b/cmake/toolchains/toolchain-aarch64-qnx.cmake
index 55cf5fbe..df9839b8 100644
--- a/cmake/toolchains/toolchain-aarch64-qnx.cmake
+++ b/cmake/toolchains/toolchain-aarch64-qnx.cmake
@@ -1,18 +1,28 @@
 set(CMAKE_SYSTEM_NAME QNX)
 set(CMAKE_SYSTEM_PROCESSOR aarch64)
 
+# Need to set the QNX_HOST and QNX_TARGET environment variables
 set(QNX_HOST $ENV{QNX_HOST})
 set(QNX_TARGET $ENV{QNX_TARGET})
 
 message(STATUS "QNX_HOST = ${QNX_HOST}")
 message(STATUS "QNX_TARGET = ${QNX_TARGET}")
 
-set(CMAKE_C_COMPILER ${QNX_HOST}/usr/bin/qcc)
-set(CMAKE_CXX_COMPILER ${QNX_HOST}/usr/bin/q++)
+find_program(QNX_QCC   NAMES qcc   PATHS "${QNX_HOST}/usr/bin")
+find_program(QNX_QPLUS NAMES q++   PATHS "${QNX_HOST}/usr/bin")
+
+if(NOT QNX_QCC OR NOT QNX_QPLUS)
+    message(FATAL_ERROR "Could not find qcc or q++ in QNX_HOST=${QNX_HOST}/usr/bin")
+endif()
+
+# Specify the cross-compilers
+set(CMAKE_C_COMPILER ${QNX_QCC})
+set(CMAKE_CXX_COMPILER ${QNX_QPLUS})
 
 set(CMAKE_C_COMPILER_TARGET aarch64)
 set(CMAKE_CXX_COMPILER_TARGET aarch64)
 
+# Set compiler flags
 set(CMAKE_CUDA_HOST_COMPILER ${CMAKE_CXX_COMPILER} CACHE STRING "" FORCE)
 set(CMAKE_CUDA_COMPILER_ID_TEST_FLAGS_FIRST "-nodlink -L${CUDA_ROOT}/lib64 -L${CUDA_ROOT}/lib -I${CUDA_ROOT}/include")