Quake III bounty: we have a winner!

At the end of February, Broadcom announced the release of full documentation for the VideoCore IV graphics core, and a complete source release of the graphics stack for the BCM21553 cellphone chip. To celebrate, we offered a $10k prize to the first person to port this codebase to the BCM2835 application processor that sits at the heart of the Raspberry Pi, and to get Quake 3 (which already runs on the Pi) running on the newly open ARM driver, rather on the closed-source VPU driver. Our hope was that the ported driver would be a helpful reference for anyone working on a Mesa/Gallium3D driver for VideoCore IV.

Hands up if you spent far too long playing this when you were young.

I’m delighted to say that we have a winner. Simon Hall is a longtime Pi hacker, who also produced the first ARMv6-accelerated copies-and-fills library back in 2012 and wrote the DMA kernel module that we integrate in our Raspbian releases. The prize couldn’t have gone to a more fitting recipient.

So, without further ado, here are Simon’s instructions for getting the driver up and running.

SETTING UP THE DEVICE

You will need:

  • a Raspberry Pi, preferably a 512MB version, with the latest Raspbian
  • a network connection
  • a monitor capable of displaying 1080p
  • an SD card, at least 8GB (10GB is recommended)

We need plenty of space to build the kernel. Compiling will take around 12 hours, so it is helpful to overclock the Pi for this task. We also require the latest firmware, and the necessary packages we’re going to use to build the code.

Note: We’re going to use gcc 4.7, as the code generated is 10% faster than with 4.6. 4.8 is 10% faster still, but this is not available on Raspbian. If you cross-compile you can get better frame times.

Enter the raspi-config utility with:

sudo raspi-config

Expand the filesystem, set the overclock to at least medium (900 MHz), and reboot. Now perform an update with:

sudo rpi-update

and reboot again. We need to install several packages. Enter the following command to do this:

sudo apt-get -y install gcc make bc screen ncurses-dev g++-4.7 libsdl1.2-dev

FETCHING THE SOFTWARE

Enter the following commands to retrieve the necessary software from GitHub:

git clone --depth=1 https://github.com/raspberrypi/linux.git
git clone https://github.com/simonjhall/challenge
git clone https://github.com/simonjhall/dma
git clone https://github.com/raspberrypi/quake3.git

BUILDING THE KERNEL

This will take around 10 hours with all kernel modules. Pruning the modules to the bare minimum can improve compile times if you wish. Enter the following commands:

cd linux
git apply ~/challenge/kernel/patch.diff
zcat /proc/config.gz > .config
make oldconfig
make menuconfig

Enter “general setup”, select “local version”, enter the string “simon” and then exit to the main menu and save. Now build the kernel with:

make ARCH=arm

INSTALLING THE KERNEL

Enter the following commands to install the new kernel:

sudo make ARCH=arm modules_install
sudo cp arch/arm/boot/Image /boot/kernel_simon.img
sudo su
echo kernel=kernel_simon.img >> /boot/config.txt
echo gpu_mem=128 >> /boot/config.txt
reboot

When the devices comes back up, verify that the new kernel is loaded with the following command:

uname -a

You should see something similar to this:

Linux raspberrypi 3.10.33simon+ #1 PREEMPT Sat Mar 22 09:49:59 UTC 2014 armv6l x

BUILDING THE REST

Enter the following commands to build the rest of the software:

cd ~/quake3
git apply ~/challenge/quake/patch.diff
./build.sh
cd ~/dma
cp ~/challenge/kernel/module/dmaer.c .
make
./install.sh

Next, verify that the module has installed with this command:

tail /var/log/kern.log

You should see something similar to this:

Mar 23 15:22:45 raspberrypi kernel: [ 20.814750] smsc95xx 1-1.1:1.0 eth0:lin1
Mar 23 15:22:45 raspberrypi kernel: [ 21.376702] bcm2835-cpufreq: switching td
Mar 23 15:22:45 raspberrypi kernel: [ 21.376710] bcm2835-cpufreq: switching td
Mar 23 15:22:46 raspberrypi kernel: [ 24.472575] Adding 102396k swap on /var/S
Mar 23 15:25:02 raspberrypi kernel: [ 143.984835] 20c00000 f2c00000 deadbeef
Mar 23 15:25:02 raspberrypi kernel: [ 143.984866] major device number 248
Mar 23 15:25:02 raspberrypi kernel: [ 143.984890] vma list size 12, page list 6
Mar 23 15:25:02 raspberrypi kernel: [ 143.984909] allocated dma channel 4(f208
Mar 23 15:25:02 raspberrypi kernel: [ 143.985242] qpu ENABLED
Mar 23 15:25:02 raspberrypi kernel: [ 143.985264] V3D identify test: V3D versi2

Now enter the following commands:

cd ~/challenge/source
make
sudo make install

SETTING UP THE GAME

First of all you must ensure that you have the Quake 3 Arena data files on your Pi. You require the ‘point release’ pak files installed. There are various ways to do this but you could either transfer them from another machine with SCP, or copy them across on a USB stick. Copy the files into a folder called ‘baseq3′. This should now contain pak files numbered from 0 to 8 (eg pak1.pk3).

Next, enter the following commands:

sudo mkdir /root/.q3a
sudo mv baseq3/ /root/.q3a/
cd ~/quake3/build/release-linux-arm/
sudo mknod char_dev c 100 0
sudo cp ~/challenge/quake/demo.cfg /root/.q3a/baseq3/

RUNNING THE GAME

Enter the game folder with the following command:

cd ~/quake3/build/release-linux-arm/

Run the game using this command:

sudo ./ioquake3.arm +exec demo

If you wish to play the game after a reboot, you must run the following commands to re-load the necessary files:

cd ~/dma
./install.sh

If you see multi-second pauses of the game, this is because the system is paging to swap! You can see this by running top at the same time, and watch the swap usage jump during a spike. Close some running programs to alleviate this problem. Running the game without gdb and loading minimal kernel modules will prevent swapping.