Most people can’t afford Juno Cortex A57/A53 development board, and mobile processors based on the latest 64-bit ARM cores are only expected by early 2015. But thanks to a small team at Linaro, you can now build and run Android L 64-bit ARM in the latest version of QEMU that supports Aarch64. Alex Bennée, an engineer working for Linaro, wrote a blog post in Linaro’s Core Dump blog explaining the Android emulator is actually based on QEMU, the differences compared to mainline QEMU, the work they’ve done on Android L at Linaro, and most importantly, provided the basic steps showing how to build and try Android L 64-bit ARM (ARMv8) in QEMU. I’ve just done that,
but unfortunately, albeit the builds complete, I could not manage to start Android L in QEMU yet. [Update: working now]. If you want to give it a try, you’ll need a Linux PC, and patience, as it may take about one day to retrieve the source code, and build everything from source.
I’ve done all this in a computer running Ubuntu 14.04 with an AMD FX8350 processor and 16 GB RAM.
First, you’ll need to install an ARM 64-bit toolchain, some dependencies, and tools:
sudo apt-get install gcc-aarch64-linux-gnu build-essentials git bison zlib1g-dev \ libglib2.0-dev libpixman-1-dev gperf android-tools-adb vncviewer
The next step is to cross-compile a Linux 3.10 kernel for Android:
mkdir -p ~/edev/linaro git clone https://git.linaro.org/people/christoffer.dall/linux-android.git cd linux-android git checkout ranchu-linaro-beta1
There’s a bug include the current version of the toolchain in Ubuntu 14.04 (https://bugs.launchpad.net/linaro-linux-baseline/+bug/1258013) which prevents the build to complete. You can either remove CONFIG_DEBUG_INFO=Y in arch/arm64/configs/ranchu_defconfig (I did that), or update your toolchain. Let’s complete the build:
ARCH=arm64 make ranchu_defconfig ARCH=arm64 make CROSS_COMPILE=aarch64-linux-gnu- -j8
Now you need to build the Android Open Source Project (AOSP). If you haven’t done so, you’ll have to install the repo tool:
mkdir ~/bin PATH=~/bin:$PATH curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo chmod a+x ~/bin/repo
Then get AOSP source code (master as below, or l-preview branch):
cd .. mkdir AOSP repo init -u https://android.googlesource.com/platform/manifest repo sync
The last step can take a few hours depending on your internet connection to Google servers.
Now download and apply a patch made by Linaro:
wget http://people.linaro.org/~christoffer.dall/linaro-devices.tar.gz tar -xvf linaro-devices.tar.gz
Possibly configure git:
git config --global user.email "[email protected]" git config --global user.name "Your Name"
You need to apply a patch for qemu:
pushd system/core wget http://people.linaro.org/~alex.bennee/android/android-init-tweaks.diff patch -p1 < android-init-tweaks.diff popd
And build Android L for ARMv8:
source build/envsetup.sh lunch ranchu-userdebug m -j8
The last step will again take a while. It took my machine 2 or 3 hours, and the total time was actually a bit more than than as my PC suffered two thermal shutdowns during the build, and I had to restart the build twice. The last time, I decided to underclock my CPU to 3.4 GHz, and the build went through.
The last step before running Android L is to build QEMU:
cd .. git clone https://git.linaro.org/people/peter.maydell/qemu-arm.git cd qemu-arm git checkout ranchu-linaro-beta1 make -j8
Builds should now all be successfully complete. We just need to create some symlinks helping to shorten qemu command line, start the ADB server, and run QEMU:
cd .. ln -s linux-android/arch/arm64/boot/ ranchu-kernel ln -s AOSP/out/target/product/ranchu/ ranchu-build adb start-server ./qemu-arm/aarch64-softmmu/qemu-system-aarch64 -cpu cortex-a57 -machine type=ranchu -m 4096 \ -kernel ./ranchu-kernel/Image -append 'console=ttyAMA0,38400 keep_bootcon' -monitor stdio \ -initrd ranchu-build/ramdisk.img -drive index=2,id=userdata,file=ranchu-build/userdata.img \ -device virtio-blk-device,drive=userdata -device virtio-blk-device,drive=cache \ -drive index=1,id=cache,file=ranchu-build/cache.img -device virtio-blk-device,drive=system \ -drive index=0,id=system,file=ranchu-build/system.img -netdev user,id=mynet \ -device virtio-net-device,netdev=mynet -show-cursor
That’s the output I get:
QEMU 2.0.50 monitor - type 'help' for more information console on port 5554, ADB on port 5555 VNC server running on `127.0.0.1:5900'
So it’s quite possible there’s a problem with adb, but Google did not help, and I failed to go further. More detailed instructions will soon be posted in Linaro Wiki, so I may be able to find out where I made a mistake once it’s posted.
Finally, start vncviewer to access Android user’s interface: