Using cross-compilation for ARM64 in the Ubuntu 24.04 x86 environment

Steven LIN

I would like to ask if my setup is correct. Why does the file not change to ARM64 after running cmake --install . ?

sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu

$ which aarch64-linux-gnu-gcc 
/usr/bin/aarch64-linux-gnu-gcc

$ aarch64-linux-gnu-gcc --version
aarch64-linux-gnu-gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

After verifying the cross-compilation tool, enter the Qt/6.8.2/ directory, create a folder, and start compiling.

cd ./Qt/6.8.2/
mkdir arm64 
mkdir build && cd build

../Src/configure -prefix /home/ptc/Qt/6.8.2/arm64 -platform linux-g++ -device linux-aarch64-gnu-g++ -device-option CROSS_COMPILE=aarch64-linux-gnu- -no-opengl -make libs

Using the file command to check the file, it is still x86.

$ file /home/ptc/Qt/6.8.2/arm64/lib/libQt6Quick.so.6.8.2
/home/ptc/Qt/6.8.2/arm64/lib/libQt6Quick.so.6.8.2: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, BuildID[sha1]=98b91422f304c376f1f70edb73b6276205a6027b, not stripped

It also cannot be executed on Qt Creator.

I would like to ask how I can resolve this issue. I would greatly appreciate it.

Steven LIN

I have already resolved the issue and successfully cross-compiled for arm64 on Ubuntu 24.04 x86 using Qt6.8.2.

I will provide my method.
The configure command is as follows:

../Src/configure \
-prefix /home/ptc/Qt/6.8.2/arm64 \
-qt-host-path /home/ptc/Qt/6.8.2/gcc_64 \
-platform linux-g++ \
-device linux-aarch64-gnu-g++ \
-device-option CROSS_COMPILE=aarch64-linux-gnu- \
-no-opengl \
-skip qtopcua -skip qtwebengine -skip qtwebview -skip qtserialport -skip qtlocation \
-no-feature-brotli -no-feature-hunspell \
-- -DCMAKE_TOOLCHAIN_FILE=$HOME/Qt/6.8.2/toolchain/arm64-toolchain.cmake

Before this, create a new toolchain.cmake file yourself.

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR aarch64)
set(CMAKE_C_COMPILER "/usr/bin/aarch64-linux-gnu-gcc")
set(CMAKE_CXX_COMPILER "/usr/bin/aarch64-linux-gnu-g++")
set(CMAKE_LINKER "/usr/bin/aarch64-linux-gnu-ld")
set(CMAKE_AR "/usr/bin/aarch64-linux-gnu-ar")
set(CMAKE_FIND_ROOT_PATH /usr/aarch64-linux-gnu)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

Next, you can follow my method to add the arm64-related dependencies on x86.

$ sudo dpkg --add-architecture arm64
$ sudo vim /etc/apt/sources.list.d/ubuntu-arm64.sources
Types: deb
URIs: http://ports.ubuntu.com/ubuntu-ports/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Architectures: arm64
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

$ sudo apt update
$ sudo apt install -y libudev-dev:arm64 libmtdev-dev:arm64

Finally, execute the configure command.

jsulm

@Steven-LIN Please don't double post.
This is same as https://forum.qt.io/topic/161304/using-cross-compilation-for-arm64-in-the-ubuntu-24-04-x86-environment?_=1741068261682

Steven LIN

@jsulm Sorry, I have already deleted the previous post.

Steven LIN

I have already resolved the issue and successfully cross-compiled for arm64 on Ubuntu 24.04 x86 using Qt6.8.2.

I will provide my method.
The configure command is as follows:

../Src/configure \
-prefix /home/ptc/Qt/6.8.2/arm64 \
-qt-host-path /home/ptc/Qt/6.8.2/gcc_64 \
-platform linux-g++ \
-device linux-aarch64-gnu-g++ \
-device-option CROSS_COMPILE=aarch64-linux-gnu- \
-no-opengl \
-skip qtopcua -skip qtwebengine -skip qtwebview -skip qtserialport -skip qtlocation \
-no-feature-brotli -no-feature-hunspell \
-- -DCMAKE_TOOLCHAIN_FILE=$HOME/Qt/6.8.2/toolchain/arm64-toolchain.cmake

Before this, create a new toolchain.cmake file yourself.

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR aarch64)
set(CMAKE_C_COMPILER "/usr/bin/aarch64-linux-gnu-gcc")
set(CMAKE_CXX_COMPILER "/usr/bin/aarch64-linux-gnu-g++")
set(CMAKE_LINKER "/usr/bin/aarch64-linux-gnu-ld")
set(CMAKE_AR "/usr/bin/aarch64-linux-gnu-ar")
set(CMAKE_FIND_ROOT_PATH /usr/aarch64-linux-gnu)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

Next, you can follow my method to add the arm64-related dependencies on x86.

$ sudo dpkg --add-architecture arm64
$ sudo vim /etc/apt/sources.list.d/ubuntu-arm64.sources
Types: deb
URIs: http://ports.ubuntu.com/ubuntu-ports/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Architectures: arm64
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

$ sudo apt update
$ sudo apt install -y libudev-dev:arm64 libmtdev-dev:arm64

Finally, execute the configure command.