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code:work:pi:rtpreempt:start

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Table of Contents

Raspberry Pi

Installing Mini Image

  1. Download the raw image https://minibianpi.wordpress.com/ 
    cd ~/work/pi
wget <<DIRECT FILE LINK>>
  2. Uncompress the image 
    md5sum 2016-03-12-jessie-minibian.tar.gz
# verify that you get
# 136cac722a4f78f49b54971ae1cc03ee  2016-03-12-jessie-minibian.tar.gz
tar -zxvf 2016-03-12-jessie-minibian.tar.gz
  3. Direct copy this image to your memory stick (mine is /dev/sdv but choose wisely!) 
    time sudo /bin/dd bs=1M if=2016-03-12-jessie-minibian.img of=/dev/sdX
  4. Resize the partition with gparted
    1. Make /dev/sdb2 fill the sdcard 
      sudo gparted /dev/sdb

:!::!: DO NOT DO THIS… USE gparted :!::!:

Manually resize partition

  1. Resize the partition to fill the entire sd scard
    1. Display the partitions and figure out which is the partition to modify 
      lsblk
    2. Show the drive geometry 
      sudo parted /dev/sdX
(parted) unit chs
(parted) print
Model: Generic STORAGE DEVICE (scsi)
Disk /dev/sdb: 490975,3,15
Sector size (logical/physical): 512B/512B
BIOS cylinder,head,sector geometry: 490976,4,16.  Each cylinder is 32.8kB.
Partition Table: msdos

Number  Start     End         Type     File system  Flags
 1      0,1,0     1953,3,15   primary  fat16
 2      1954,0,0  25407,3,15  primary  ext4
    3. Remove partition 2 
      (parted) rm 2
    4. Define 2 now as all of the the drive (this goes with the geometry above) 
      mkpart primary 1954,0,0 490975,3,15

Cross Compiling

Attempting to cross compile on the GUI computer

GUI Compiler Setup

  1. Grab the toolchain 
    cd ~/work
mkdir pi
cd ~/work/pi
git clone https://github.com/raspberrypi/tools
  2. Add this to your PATH
    1. First edit your profile
      nano ~/.profile
    2. And add this line 
      # add raspberry pi toolchain to path
PATH="$HOME/work/pi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin:$PATH"
  3. Grab source code 
    cd ~/work/pi
git clone --depth=1 https://github.com/raspberrypi/linux

GUI Compile

Try compiling the source we just downloaded

  1. Step one: setup 
    cd ~/work/pi/linux
KERNEL=kernel7
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig
  2. Step two: build 
    make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs -j `getconf _NPROCESSORS_ONLN`

Install on the sd card

  1. Create mount points and mount the card partitions to them 
    cd /mnt
sudo mkdir pisdcard
sudo mkdir pisdcard/fat32
sudo mkdir pisdcard/ext4
sudo mount /dev/sdb1 /mnt/pisdcard/fat32
sudo mount /dev/sdb2 /mnt/pisdcard/ext4
  2. Install the kernel on the ext4 partition 
    # go where the kernel is that you want to install
cd /home/lvis/work/pi/linux_original
sudo make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=/mnt/pisdcard/ext4 modules_install
  3. Backup the kernel on there, and then install our new kernel on the fat32 partition 
    sudo cp /mnt/pisdcard/fat32/$KERNEL.img /mnt/pisdcard/fat32/$KERNEL-backup.img
sudo scripts/mkknlimg arch/arm/boot/zImage /mnt/pisdcard/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb /mnt/pisdcard/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* /mnt/pisdcard/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README /mnt/pisdcard/fat32/overlays/
sync
sudo umount /mnt/pisdcard/fat32
sudo umount /mnt/pisdcard/ext4

GUI RT PREEMPT Patch Compile

  1. Copy code and patch 
    cd ~/work/pi
wget https://www.kernel.org/pub/linux/kernel/projects/rt/4.9/patch-4.9.13-rt10.patch.xz
rsync -vaP linux_original/ linux_4.9.13_rt10/
cd /home/lvis/work/pi/linux_4.9.13_rt10
xz -dc ../patch-4.9.13-rt10.patch.xz | patch -p1
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- clean
  2. Setup 
    cd ~/work/pi/linux_4.9.13_rt10
KERNEL=kernel7
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig
  3. Modify the .config file to enable RT_PREEMPT
    1. Load up the x11 configuration editor
      make xconfig
    2. Search for “PREEMPT”
    3. Processor type and features
      1. Preemption Model (Fully Preemptible Kernel (RT))
      2. Timer frequency (1000 HZ)
    4. Power management and ACPI options
      1. REMOVE Device power management core functionality
      2. CPU Frequency scaling
        1. REMOVE CPU Frequency scaling
    5. Verify with a quick grep 
      lvis@lvis-desktop:~/work/pi/linux_4.9.13_rt10$ cat .config | grep PREEMPT
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT=y
CONFIG_HAVE_PREEMPT_LAZY=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT__LL=y
# CONFIG_PREEMPT_RTB is not set
# CONFIG_PREEMPT_RT_FULL is not set
CONFIG_PREEMPT_COUNT=y
CONFIG_DEBUG_PREEMPT=y
# CONFIG_PREEMPT_TRACER is not set
  4. Build (had to press enter a BUNCH of times to accept defaults when I changed kernel config) 
    make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs -j `getconf _NPROCESSORS_ONLN`

Install on the sd card

  1. Create mount points and mount the card partitions to them 
    cd /mnt
sudo mkdir pisdcard
sudo mkdir pisdcard/fat32
sudo mkdir pisdcard/ext4
sudo mount /dev/sdb1 /mnt/pisdcard/fat32
sudo mount /dev/sdb2 /mnt/pisdcard/ext4
  2. Install the kernel on the ext4 partition
    # go where the kernel is that you want to install
cd ~/work/pi/linux_4.9.13_rt10
sudo make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=/mnt/pisdcard/ext4 modules_install
  3. Backup the kernel on there, and then install our new kernel on the fat32 partition 
    sudo cp /mnt/pisdcard/fat32/$KERNEL.img /mnt/pisdcard/fat32/$KERNEL-backup.img
sudo scripts/mkknlimg arch/arm/boot/zImage /mnt/pisdcard/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb /mnt/pisdcard/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* /mnt/pisdcard/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README /mnt/pisdcard/fat32/overlays/
  4. Add this line to /boot/cmdline.txt which can cause kernel panic if not disabled
    1. Edit this file 
      sudo nano /mnt/pisdcard/fat32/cmdline.txt
    2. and add these statements 
      # found this additional one too 
# http://www.frank-durr.de/?p=203
# Most people also disable the Low Latency Mode (llm) for the SD card:

sdhci_bcm2708.enable_llm=0 dwc_otg.fiq_enable=0 dwc_otg.fiq_fsm_enable=0 dwc_otg.nak_holdoff=0
  5. Unmount the drives 
    sync  # just run this before unmounting the drives.. flush the cache
sudo umount /mnt/pisdcard/fat32
sudo umount /mnt/pisdcard/ext4

Boot Pi

  1. Insert sd card into Pi
  2. FIXME Insert the keyboard into the Pi (WITHOUT a device in there… the kernel panics on boot!)
  3. Default user/pass is root and raspberry which I changed to the lvis standard password

Cyclic Test

We want to run cyclic test on here to make sure that the performance on the Pi is what we need /home/lvis/work/pi/linux_4.9.13_rt10

  1. Update our software 
    apt-get update
apt-get upgrade
  2. Install gcc git 
    apt-get install build-essential git
  3. Download the cyclic test code (found from here: https://rt.wiki.kernel.org/index.php/Cyclictest) 
    mkdir ~/work
cd ~/work
git clone git://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git
  4. Checkout the stable version 
    cd ~/work/rt-tests
git fetch
git checkout stable/v1.0
  5. Compile and install 
    make all
cp ./cyclictest /usr/local/bin/
  6. Try it out 
    cyclictest -a -t -n -p99
# use priority 80 and interval of 4khz
cyclictest -m -t -p 80 -n -i 250

Xenomai

cd /home/lvis/work/pi
mkdir download
cd download
wget https://xenomai.org/downloads/ipipe/v4.x/arm/ipipe-core-4.1.18-arm-9.patch
wget https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.1.18.tar.xz
wget https://xenomai.org/downloads/xenomai/stable/latest/xenomai-3.0.3.tar.bz2

wget https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.4.43.tar.xz
wget https://xenomai.org/downloads/ipipe/v4.x/arm/ipipe-core-4.4.43-arm-7.patch

# uncompress kernel
cd /home/lvis/work/pi
tar xf download/linux-4.1.18.tar.xz 
mv linux-4.1.18 linux-4.1.18-ipipe

tar xf download/linux-4.4.43.tar.xz 
mv linux-4.4.43 linux-4.4.43-ipipe


# uncompress xenomai
tar xvf download/xenomai-3.0.3.tar.bz2

# copy the latest ipipe patch for 4.1.18 in to the patch directory
cd /home/lvis/work/pi/xenomai-3.0.3
# cp ../download/ipipe-core-4.1.18-arm-9.patch kernel/cobalt/arch/arm/patches/
cp -a ../download/ipipe-core-4.4.43-arm-7.patch xenomai-3.0.3/kernel/cobalt/arch/arm/patches/

# patch kernel
cd ~/work/pi/xenomai-3.0.3
./scripts/prepare-kernel.sh --linux=~/work/pi/linux-4.1.18-ipipe
./scripts/prepare-kernel.sh --linux=~/work/pi/linux-4.4.43-ipipe
# and type "arm" for architecture (no errors)

# configure kernel (first default, then we change it)
KERNEL=kernel7
cd ../linux-4.1.18-ipipe
cd ../linux-4.4.43-ipipe
#### make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- menuconfig
  * CPU Power Management * Turn it all off
  * Kernel Features * Preemption Model (Preemptible Kernel (Low-Latency Desktop))
  * Kernel Features * [NO] Allow for memory compaction
  * Kernel Features * [NO] Contiguous Memory Allocator
  │   Selected by: COMPACTION [=y] && MMU [=y] || CMA [=y] && HAVE_MEMBLOCK [=y] && MMU [=y]
** for sage build, not doing this ** enabling this CONFIG_XENO_OPT_SHIRQ
  * Had to disable the Intel ethernet modules... it had an error, just disabled ALL Intel ethernet...
  * Had to disable lustre driver from device -> staging
  * Had to disable  CAIF virtio transport driver

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs -j `getconf _NPROCESSORS_ONLN`

Xenomai Pi Compiled

This did compile for me, haven't tried it yet! — David Lloyd Rabine 2017/03/04 20:55 

cd ~/work/pi
tar xf download/linux-3.18.20.tar.xz
mv linux-3.18.20 linux-3.18.20-ipipe
cd xenomai-3.0.3
scripts/prepare-kernel.sh --arch=arm --linux=~/work/pi/linux-3.18.20-ipipe
cd ~/work/pi/linux-3.18.20-ipipe
KERNEL=kernel7
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2709_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- bcm2835_defconfig

# make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage modules dtbs
# no modules!?

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- menuconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage dtbs -j `getconf _NPROCESSORS_ONLN`

cd /mnt
sudo mkdir pisdcard
sudo mkdir pisdcard/fat32
sudo mkdir pisdcard/ext4
sudo mount /dev/sdb1 /mnt/pisdcard/fat32
sudo mount /dev/sdb2 /mnt/pisdcard/ext4

# go where the kernel is that you want to install
cd ~/work/pi/linux_4.9.13_rt10
sudo make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=/mnt/pisdcard/ext4 modules_install

# and the rest
sudo cp /mnt/pisdcard/fat32/$KERNEL.img /mnt/pisdcard/fat32/$KERNEL-backup.img
sudo scripts/mkknlimg arch/arm/boot/zImage /mnt/pisdcard/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb /mnt/pisdcard/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* /mnt/pisdcard/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README /mnt/pisdcard/fat32/overlays/

Xenomai Application Example from /home/david/src/pi/xenomai-3.0.3/demo/posix/cobalt/eth_p_all.c 

 pthread_setschedparam(pthread_self(), SCHED_FIFO, &param);

 while(1)
 {

 }

Another good example /home/david/src/pi/xenomai-3.0.3/demo/posix/cobalt/xddp-echo.c

This example sends data down the pipe to keep from context switching which is probably what is causing Dan's code to not keep up.

  • This is an excellent example that has a real time thread and a non-real time thread that communicate.
code/work/pi/rtpreempt/start.1488823235.txt.gz · Last modified: 2017/03/06 18:00 by david