View source for LDC cross-compilation for ARM GNU/Linux

<span style="color:red">'''This page is outdated and we are working on much better cross-compilation support, [[Building LDC runtime libraries|try the new runtime cross-compilation tool instead]].'''</span>


This page will show you how to build a ldc cross-compiler for ARM architecture on GNU/Linux, so that you can build an executable binary with the druntime/phobos and run it on your ARM target.

==Prerequisites==

* Linux host, where you'll build and run ldc.
* C/C++ toolchain, to build llvm and parts of ldc.
* A pre-built D compiler for GNU/Linux, needed because the ldc frontend is written in D.
** You can get [http://dlang.org/download the official dmd release for Linux] or [https://github.com/ldc-developers/ldc/releases one of the ldc releases for Linux].
* Common development tools, such as CMake and git, and ldc uses libconfig++
* ldc/druntime/phobos source
* llvm 3.8 source, either from the official release or git.
* GNU ARM toolchain that supports your ARM target [https://launchpad.net/gcc-arm-embedded]
** In this example, GNU ARM Embedded Toolchain 4.3.3-2009-q1 is used, installed on the host at <tt>/opt/arm-2009q1</tt>
* An ARM target with a running GNU/Linux installed on it (like an Ubuntu distribution installed on a Raspberry Pi)

==Compile llvm==

Get the source for llvm, either [http://llvm.org/releases/download.html#3.8.0 the latest official 3.8.0 release] or [https://github.com/llvm-mirror/llvm a git repository, like this llvm mirror]. [http://llvm.org/docs/GettingStarted.html#getting-started-quickly-a-summary Build llvm as you would normally], with the ARM target:

<syntaxhighlight lang=bash>
curl -O http://llvm.org/releases/3.8.0/llvm-3.8.0.src.tar.xz
tar xvf llvm-3.8.0.src.tar.xz

mkdir llvm-3.8.0.arm_obj/
cd llvm-3.8.0.arm_obj/
cmake ../llvm-3.8.0.src -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD=ARM
make -j5
</syntaxhighlight>

==Build ldc for GNU/ARM==

Clone the ldc repository, check out the release-1.0.0 branch, [https://gist.github.com/claudemr/3367c13095b15d449b1591eb38d098d9 apply the ARM patch], set the DMD environment variable to the path of your pre-built D compiler, and [[Building LDC from source|build ldc, druntime and phobos as usual]]:

<syntaxhighlight lang=bash>
cd ..
git clone --recursive https://github.com/ldc-developers/ldc.git
cd ldc/
git checkout -b ddmd origin/release-1.0.0
git submodule update
curl -O https://gist.githubusercontent.com/claudemr/3367c13095b15d449b1591eb38d098d9/raw/3517a5db2228e57da9dd8880a82d6bfe6f0e38f1/ldc_1.0.0_gnu_arm
git apply ldc_1.0.0_gnu_arm

mkdir build_arm
cd build_arm
export DMD=/path/to/your/dmd2/linux/bin64/dmd
cmake .. -DLLVM_CONFIG=../../llvm-3.8.0.arm_obj/bin/llvm-config
make druntime-ldc phobos2-ldc -j5
</syntaxhighlight>

==Build a command-line executable==

Now that we have a D cross-compiler and cross-compiled the standard library for GNU/ARM, let's try building a small program, the classic [https://wiki.dlang.org/The_D_Programming_Language Hello world]:

<syntaxhighlight lang=bash>
./bin/ldc2 -v -mtriple=arm-none-linux-gnueabi -gcc=/opt/arm-2009q1/bin/arm-none-linux-gnueabi-gcc helloworld.d
</syntaxhighlight>

Push and run this program on an ARM device with GNU/Linux

==Directions for future work==

* Run druntime and phobos unit-tests.

[[Category:LDC]]
[[Category:ARM]]
[[Category:GNU/Linux]]