This is a step-by-step guide on how to cross-compile Steem for Windows on a Linux host.
I have spent a lot of time making changes to the Steem codebase and writing my own custom build scripts to make this process relatively painless for someone who is familiar with Linux.
I have not yet tried to see if I can get this (or a similar process) to work on a Windows host (using MSYS2 perhaps). So you still need access to a Linux machine to build the Windows executables, for now.
For this guide to work, you need a version of Steem that has my changes included. As of this moment on May 22, 2016, only my Steem repo has those changes. However, I have submitted pull requests to get these changes included in the official codebase.
Edit: As of v0.5.0, my changes have been included into the official codebase. So the guide below has been updated to use v0.5.0 from Steemit's steem repo.
This was all done on a fresh installation of Ubuntu Server 16.04. It will likely work with other Linux distros, but I cannot guarantee it and some of the instructions may need to change.
We first need to get some initial setup out of the way. Some of this will require root permissions via sudo.
First we need to install packages for the toolchains we will be using.
~$ sudo apt-get install build-essential cmake mingw-w64 autoconf libtool doxygen
Then create a directory with a short absolute path to work within. This is so that we get consistent (and privacy-preserving) strings within the compiled executables.
~$ sudo mkdir /r
~$ sudo chown 1000:1000 /r
~$ cd /r
Make sure to chown the directory with your user and group so that you have write permission in that directory.
Let us create a few more useful directories within the /r directory.
/r$ mkdir mingw
/r$ mkdir src
/r$ mkdir build
Steem has two external dependencies: Boost and OpenSSL. Both of these will need to be compiled with the same MinGW compiler as the one used to compile Steem for things to link properly.
Cross-compiling these dependencies gets a little tricky, so you will need the handy scripts I have made to help automate this process. We need to get and install these scripts now.
/r$ cd /r/src
/r/src$ wget -O steem_dependencies_build_scripts.tar.gz https://gateway.ipfs.io/ipfs/QmWuT4PoJ9snfjGL49pi32WLUeQWzrZKWw7G3DnDrLCwkT
/r/src$ tar -xzf steem_dependencies_build_scripts.tar.gz
Cross-compiling Boost for a Windows target on a Linux host is tricky because one of the libraries, Boost.Context, needs to assemble some assembly code. However, the Boost codebase is only set up to support one compiler per target, and for the Windows target that compiler is MASM. Unfortunately, MASM only runs on Windows, but we need the assembler to run on the Linux host.
The solution is to use an open-source alternative to MASM called JWasm. The command-line interface for JWasm is not exactly the same as MASM, but I have written a Python script "steem_dependencies_build_scripts/helper/ml64" which wraps jwasm and converts the arguments passed to the script into a form acceptable by jwasm. It is a fragile hack, but it gets the job done.
So let us grab the source for JWasm, compile it, and install it in a location that is within the system PATH.
/r/src$ git clone https://github.com/JWasm/JWasm.git
/r/src$ cd JWasm
/r/src/JWasm$ make -f GccUnix.mak
/r/src/JWasm$ sudo cp GccUnixR/jwasm /usr/local/bin/
/r/src/JWasm$ cd ..
From this point on we should not need sudo or root permissions anymore.
Building OpenSSL is straightforward using my script.
/r/src$ wget https://www.openssl.org/source/openssl-1.0.2h.tar.gz
/r/src$ tar -xzf openssl-1.0.2h.tar.gz
/r/src$ cd openssl-1.0.2h
/r/src/openssl-1.0.2h$ /r/src/steem_dependencies_build_scripts/mingw_build_openssl.sh
/r/src/openssl-1.0.2h$ cd ..
Apparently, Steem does not currently build against Boost 1.61. It does build against Boost 1.59 and 1.60, but I found that the resulting executables for both versions were not functioning properly for some reason. The latest version of Boost that Steem (at least the cross-compiled version) does work well with is Boost 1.58.0. So we will build that.
/r/src$ wget http://downloads.sourceforge.net/project/boost/boost/1.58.0/boost_1_58_0.tar.bz2
/r/src$ tar -xjf boost_1_58_0.tar.bz2
/r/src$ cd boost_1_58_0
/r/src/boost_1_58_0$ /r/src/steem_dependencies_build_scripts/mingw_build_boost.sh -j2
/r/src/boost_1_58_0$ cd ..
Feel free to replace (or even get rid of) the -j2 flag with -jN where N is the number of cores on your machine.
At this point the external dependencies for Steem have been built and installed at /r/mingw.
We now need to build Steem itself.
We will be building v0.5.0. Feel free to update these instructions to build any later versions.
/r/src$ git clone https://github.com/steemit/steem.git
/r/src$ cd steem
/r/src/steem$ git checkout v0.5.0
/r/src/steem$ git submodule update --init --recursive
/r/src/steem$ cd ../..
I like to build Steem out of the source directory. This allows me to better manage all the different types of builds (release/debug, full/witness, linux/windows) for all the different versions of Steem I compile.
So let us first set up the directory for the build and cd into it.
/r$ cd build
/r/build$ mkdir -p steem/v0.5.0/windows-full-release
/r/build$ cd steem/v0.5.0/windows-full-release
We can now run cmake to configure the build. However, because the options get very complicated for a cross-compile build, I have created a helper script that simplifies the process. This script is actually included with the Steem codebase. In fact, it is not just for cross-compilation. It works well for regular compilation as well. I encourage you to play around with it. The usage and help (accessible by running /r/src/steem/programs/build_helpers/configure_build.py -h) documents how to use it pretty decently.
/r/build/steem/v0.5.0/windows-full-release$ /r/src/steem/programs/build_helpers/configure_build.py --sys-root=/r/mingw -f -r --win
After running that command, cmake should have successfully built the files into the directory.
Note that -f -r options configured the build to be a Release build of a full node (meaning -DLOW_MEMORY_NODE=OFF), which is the default if you do not pass any flags. By the way, my changes to the code (included in the pull request) means that -DENABLE_CONTENT_PATCHING=ON is no longer necessary because the code no longer depends on Qt5 to run the patching algorithm.
If you wanted to build a witness node instead, you would pass -w instead of -f. And if you wanted a Debug build, you would pass -d instead of -r.
The --win flag is to tell the build script that this is a Windows cross-compilation build. Leaving it off would make it build Steem for the native platform like usual. Because --win is specified, it is essential to also specify the --sys-root so that the build script knows where the MinGW-w64 compiled Boost and OpenSSL dependencies reside.
Now, all that is left is to actually compile Steem.
/r/build/steem/v0.5.0/windows-full-release$ make -j2
Once again feel free to change the -j2 flag.
If all went well, you should have steemd.exe located at /r/build/steem/v0.5.0/windows-full-release/programs/steemd/steemd.exe and cli_wallet.exe located at /r/build/steem/v0.5.0/windows-full-release/programs/cli_wallet/cli_wallet.exe.
These are fully static builds which means the executables work by themselves on a 64-bit Windows machine. There is no need to install any other libraries on the Windows host.