WebKit2GTK+ cross-compilation environment for ARM

Resources to allow cross compiling WebKit2GTK+ for ARM.

Requirements

• A host machine with lots of CPUs and RAM (16GB recommended)
• RootFS for the target device
  • You must adjust the path in the CMake Toolchain file accordingly (e.g /schroot/eos-master-armhf)
• Packages to create and use the chroot: debootstrap, chroot and schroot
  • Debian/Ubuntu: sudo apt-get install debootstrap coreutils schroot
  • Fedora: sudo dnf install debootstrap chroot schroot

NOTE: These instructions bootstrap a chroot with Ubuntu 16.04 "Xenial Xerus" on your machine. Yes this version is no longer supported by Canonical, but it should still work.

Instructions

(1) First, use debootstrap to create a directory to host our chroot, adjusting /path/to/chroot accordingly (e.g /schroot/eos-master-armhf):

$ sudo /usr/sbin/debootstrap \
       --components=main,universe \
       xenial /path/to/chroot http://uk.archive.ubuntu.com/ubuntu

NOTE: If this gets stuck at "Configuring keyboard-configuration...", try breaking out with CTRL+C and re-running the command.

(2) Create a configuration file for the schroot tool, for example /etc/schroot/chroot.d/xenial-amd64, with the following contents (replacing <username>, <group>, and /path/to/chroot accordingly):

[xenial-amd64]
description=Ubuntu 64-bit chroot based on Xenial
type=directory
directory=/path/to/chroot
users=<username>
groups=<group>
root-users=<username>
setup.copyfiles=default/copyfiles
setup.fstab=default/xenial-amd64.fstab

(3) Next you need to create the mentioned fstab file under /etc/schroot/default so that schroot can bind mount the path to the RootFS. To do that, create a copy of /etc/schroot/default/fstab (sudo cp /etc/schroot/default/fstab /etc/schroot/default/xenial-amd64.fstab), then add this line to its contents, changing /path/to/chroot accordingly:

# To crosscompile WebKitGTK
/path/to/chroot  /path/to/chroot        none    rw,bind         0       0

IMPORTANT: the second column specifies the mount point inside the chroot, and it must match the path referenced in the CMake Toolchain file.

(4) You should now be able to enter the chroot from your user session (sudo not required):

$ schroot -c xenial-amd64

NOTE: If you get a warning like Failed to change to directory ‘/etc/schroot/default’: No such file or directory, don't worry. As the warning suggests, the directory you were in before starting schroot doesn't exist inside the chroot. Chroots often have far fewer things installed, and running schroot without --directory attempts to chdir into the directory you were in before. You can confirm this by looking at the root directory (ls -l /). It should be nearly identical to your /path/to/chroot. The fstab change we made is what lets you see /path/to/chroot from inside the chroot.

(5) From inside the chroot, run the bootstrap.sh script as the root user (or using sudo) provided with this repository to provision it with the tools you need to build Webkit, and then copy the armv7l-toolchain.cmake file to some local path, and you're good to go.

(6) Next create a BUILD directory in /path/to/your/WebKit and configure the build (you might want to pass extra/different parameters, though) from inside the chroot:

$ mkdir /path/to/your/WebKit/BUILD && cd /path/to/your/WebKit/BUILD
$ cmake -DCMAKE_TOOLCHAIN_FILE=/home/mario/work/webkit2gtk-ARM/armv7l-toolchain.cmake \
        -DPORT=GTK \
        -DCMAKE_BUILD_TYPE=Release \
        -DCMAKE_INSTALL_SYSCONFDIR=/etc \
        -DCMAKE_INSTALL_LOCALSTATEDIR=/var \
        -DCMAKE_INSTALL_PREFIX=/usr \
        -DCMAKE_INSTALL_LIBDIR=lib/arm-linux-gnueabihf \
        -DCMAKE_INSTALL_LIBEXECDIR=lib/arm-linux-gnueabihf \
        -DENABLE_PLUGIN_PROCESS_GTK2=OFF \
        -DENABLE_GEOLOCATION=OFF \
        -DENABLE_GLES2=ON \
        -DUSE_LD_GOLD=OFF \
        /path/to/your/WebKit

(7) Finally, from inside the chroot, build WebKit:

$ make VERBOSE=1 -j12    # Or anything else, this is just what I use

And that should be all. You now should be able to copy the output files over to the target machine and run your cross-compiled WebKit build.

Enjoy!