This repository holds a fork of Raspberry Pi Linux kernel patched with rt-patch and configured as a fully preemtible kernel. Instructions on compiling, setting up and testing the kernel are provided below.
Download Raspberry Pi tools:
git clone https://github.com/raspberrypi/tools.git
Download kernel sources and switch to rt branch:
git clone https://github.com/emlid/linux-rt-rpi.git
cd linux-rt-rpi
git checkout rpi-3.18.7-rt1
Export the following variables to specify cross-compilation options:
export ARCH=arm
export CROSS_COMPILE=~/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-
For Raspberry Pi:
make bcmrpi_rt_defconfig
For Raspberry Pi 2:
make bcm2709_rt_defconfig
Optional: make changes to the config
make menuconfig
Compile the kernel:
make -j5
Install modules, will result in "lib" folder with modules and firmware:
mkdir kernel-rt
INSTALL_MOD_PATH=kernel-rt make modules_install
Copy kernel:
For Raspberry Pi:
Copy arch/arm/boot/Image to /boot/kernel.img on SD card.
Copy arch/arm/boot/dts/bcm2708-rpi-b.dtb to /boot/bcm2708-rpi-b.dtb on SD card
Copy arch/arm/boot/dts/bcm2708-rpi-b-plus.dtb to /boot/bcm2708-rpi-b-plus.dtb on SD card
Copy (merge if necessary) kernel-rt/lib to / on SD card.
For Raspberry Pi 2:
Copy arch/arm/boot/Image to /boot/kernel7.img on SD card.
Copy arch/arm/boot/dts/bcm2709-rpi-2-b.dtb to /boot/bcm2709-rpi-2-b.dtb on SD card
Copy (merge if necessary) kernel-rt/lib to / on SD card.
Now you can insert an SD card into your Raspberry Pi and check if it boots. If something is wrong it is recommended to observe serial console.
Installing cyclictest utility on Raspberry Pi:
git clone git://git.kernel.org/pub/scm/linux/kernel/git/clrkwllms/rt-tests.git
cd rt-tests
make all
cp ./cyclictest /usr/bin/
cd ~
Testing real-time:
sudo cyclictest -l1000000 -m -n -a0 -t1 -p99 -i400 -h400 -q