|
|
| (2 intermediate revisions by 2 users not shown) |
| Line 1: |
Line 1: |
| = How to use a Linux-to-Linux cross compiling GNU toolchain =
| | {{CMake/Template/Moved}} |
|
| |
|
| Linux is in widespread use in embedded systems and handheld devices. There are many commercial
| | This page has moved [https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/cross_compiling/Eldk here]. |
| and non-commercial projects which provide cross compiling toolchains, one of these
| |
| is [http://www.denx.de Denx], which offer the [http://www.denx.de/wiki/DULG/ELDK Embedded Linux Development Kit],
| |
| short ELDK. ELDK supports PowerPC, ARM and MIPS as target systems, it consists of the cross compiling toolchains and
| |
| the quite complete target environment.
| |
| ELDK shouldn't be much different from other cross compiling toolchains, so the information presented here should be usable also for other Linux-to-Linux cross compiling toolchains.
| |
| | |
| == Installing ELDK ==
| |
| | |
| You can find installation instructions at http://www.denx.de/wiki/view/DULG/ELDKDownloadPowerPC , the
| |
| packages are available at ftp://ftp.sunet.se/pub/Linux/distributions/eldk/ .
| |
| E.g. if your target has a MIPS processor, you will download the files you can find in
| |
| ftp://ftp.sunet.se/pub/Linux/distributions/eldk/4.1/mips-linux-x86/iso . The easiest way to use them is to mount
| |
| these ISO files and then install ELDK using the ''install'' executable you will find there:
| |
| <pre>
| |
| ~/ $ mkdir mount-iso/
| |
| ~/ $ sudo mount -tiso9660 mips-2007-01-21.iso mount-iso/ -o loop
| |
| ~/ $ cd mount-iso/
| |
| ~/mount-iso/$ ./install -d /home/alex/eldk-mips/
| |
| ...
| |
| Preparing... ########################################### [100%]
| |
| 1:appWeb-mips_4KCle ########################################### [100%]
| |
| Done
| |
| ~/mount-iso/$ ls eldk-mips/
| |
| bin eldk_init etc mips_4KC mips_4KCle usr var version
| |
| </pre>
| |
| | |
| In eldk-mips/mips_4KC/ and eldk-mips/mips_4KCle/ the target environments have been installed, i.e. complete Linux
| |
| filesystems for the target platforms. In eldk-mips/bin/, eldk-mips/usr/ etc. host side tools
| |
| have been installed, so the cross compiler can be found in eldk-mips/usr/bin/mips-linux-gcc.
| |
| | |
| | |
| == Writing a CMake toolchain file ==
| |
| | |
| For CMake to be able to crosscompile software, it requires you to write a toolchain file, which tells CMake
| |
| some information about the toolchain.
| |
| With the examples used above it will look like:
| |
| <pre>
| |
| # the name of the target operating system
| |
| SET(CMAKE_SYSTEM_NAME Linux)
| |
| | |
| # which C and C++ compiler to use
| |
| SET(CMAKE_C_COMPILER /home/alex/eldk-mips/usr/bin/mips_4KC-gcc)
| |
| SET(CMAKE_CXX_COMPILER /home/alex/eldk-mips/usr/bin/mips_4KC-g++)
| |
| | |
| # here is the target environment located
| |
| SET(CMAKE_FIND_ROOT_PATH /home/alex/eldk-mips/mips_4KC /home/alex/eldk-mips-extra-install )
| |
| | |
| # adjust the default behaviour of the FIND_XXX() commands:
| |
| # search headers and libraries in the target environment, search
| |
| # programs in the host environment
| |
| set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
| |
| set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
| |
| set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
| |
| </pre>
| |
| | |
| Save this file as Toolchain-eldk-mips4KC.cmake to some location where you will put
| |
| all your toolchain files, e.g. $HOME.
| |
| | |
| == Building the software for ELDK ==
| |
| | |
| Let's say you have the classical hello world software with a CMake based buildsystem and want to build this for ELDK.
| |
| main.c:
| |
| <pre>
| |
| include <stdio.h>
| |
| | |
| int main()
| |
| {
| |
| printf("Hello world\n");
| |
| return 0;
| |
| }
| |
| </pre>
| |
| | |
| CMakeLists.txt:
| |
| <pre>
| |
| ADD_EXECUTABLE(hello main.c)
| |
| INSTALL(TARGETS hello DESTINATION bin)
| |
| </pre>
| |
| | |
| Then run CMake on it to generate the buildfiles, the important point is that you tell it to use the toochain file you just wrote:
| |
| <pre>
| |
| ~/src/helloworld/ $ mkdir build
| |
| ~/src/helloworld/ $ cd build
| |
| ~/src/helloworld/build/ $ cmake -DCMAKE_TOOLCHAIN_FILE=~/Toolchain-eldk-mips4KC.cmake -DCMAKE_INSTALL_PREFIX=/home/alex/eldk-mips-extra-install ..
| |
| -- Configuring done
| |
| -- Generating done
| |
| -- Build files have been written to: /home/alex/src/helloworld/build
| |
| ~/src/helloworld/build/ $ make
| |
| Scanning dependencies of target hello
| |
| [100%] Building C object CMakeFiles/hello.dir/main.o
| |
| Linking C executable hello
| |
| [100%] Built target hello
| |
| ~/src/helloworld/build/ $ make install
| |
| ...
| |
| -- Installing /home/alex/eldk-mips-extra-install/bin/hello
| |
| </pre>
| |
| | |
| So that's all. It actually doesn't matter whether it's just a "hello world" or some complex piece of software,
| |
| the only difference is the usage of the toolchain file. If the software has all required configure checks, it should just
| |
| build also for ELDK.
| |
