create-mint-rt.md

This document is about modifying an existing standard linux mint distro.

download a linux mint disto in iso format. download & compile kernel with realtime extension. add kernel to iso. add programs to the iso. repack the iso. test the iso.

Iso to download : https://gnipsel.com/linuxcnc/uspace/linuxmint19-rt.html, burn it on a usb storage device.

follow the steps for chrooting : https://github.com/grotius-cnc/debian_distro_live_build_post_tweaking/blob/main/create-bullseye-rt.md

Mint related actions :

To get internet as chroot in Mint, copy a file.

host pc file : /etc/resolv.conf
copy this file to your unpacked iso, squashfs-root/etc/ 

Chroot

mount --bind /dev squashfs-root/dev
mount --bind /dev/pts squashfs-root/dev/pts
mount --bind /sys squashfs-root/sys
mount --bind /proc squashfs-root/proc
chroot squashfs-root
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
export LC_ALL=C

ping www.google.nl  (cntr+z to stop)

echo"deb http://packages.linuxmint.com rafaela main upstream import" > /etc/apt/sources.list
echo"deb http://extra.linuxmint.com rafaela main" >> /etc/apt/sources.list
echo"deb http://archive.ubuntu.com/ubuntu trusty main restricted universe multiverse" >> /etc/apt/sources.list
echo"deb http://archive.ubuntu.com/ubuntu trusty-updates main restricted universe multiverse" >> /etc/apt/sources.list
echo"deb http://security.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse" >> /etc/apt/sources.list
echo"deb http://archive.canonical.com/ubuntu/ trusty partner" >> /etc/apt/sources.list

apt-get update

apt-get install -y build-essential bin86 kernel-package libssl-dev
apt-get install -y libqt4-dev libncurses5-dev pkg-config

mkdir -p /home/rtlinux && cd /home/rtlinux

Find some kernels, this is a gamble for me.

wget https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.11.4.tar.xz \
https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/5.11/patch-5.11.4-rt11.patch.gz

tar -xpf linux-5.11.4.tar.xz
gunzip patch-5.11.4-rt11.patch.gz
cp patch-5.11.4-rt11.patch linux-5.11.4
cd linux-5.11.4
cat patch-5.11.4-rt11.patch | patch -p1

Needed by xconfig

apt-get install qt5-default qttools5-dev-tools qttools5-dev

X display needed by xconfig. Let's install one.

apt-get install dbus-x11 xorg xinit xnest

I did this in the chroot environment and in the host system environment, somehow when "make xconfig" was done a x window popped up.

xhost +local:
echo $DISPLAY
export DISPLAY=:0

make xconfig

Now you are in the kernel configurator window, this seems to be oke configured for preempt rt, i selected also "enable parport" and closed the window.

apt-get install libelf-dev
make -j2

sudo make modules_install
sudo make install

update-grub

umount /dev /dev/pts /sys /proc
exit
cd

Reboot host pc, to be sure. Copy some file's higher in file hierargy

cp /casper/squashfs-root/boot/initrd.img-5.11.4-rt11 /casper
cp /casper/squashfs-root/boot/vmlinuz-5.11.4-rt11 /casper
cp /casper/squashfs-root/boot/config-5.11.4-rt11 /casper
cp /casper/squashfs-root/boot/System.map-5.11.4-rt11 /casper

Repack the iso.

mksquashfs squashfs-root/ filesystem.squashfs -comp xz

Edit /.disk/info

Linux Mint 19.1 Rtos

Create new iso in top level dir :

xorriso -as mkisofs -V 'Linux Mint 19.1 Rtos' \
-o Linux-Mint-19.1-Rtos.iso -J -J -joliet-long -cache-inodes \
-isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
-b isolinux/isolinux.bin \
-c isolinux/boot.cat -boot-load-size 4 -boot-info-table -no-emul-boot -eltorito-alt-boot \
-e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat -isohybrid-apm-hfsplus .

Output 2.2Gb iso.

Output 2.1Gb filesystem.squashfs on iso with a max to 4Gb = ((4 max - 2.1 used ) * 2.7 ratio) = 5.13 Gb may be extra used.

Put it on a usb storage device.

sudo dd bs=4M if=Linux-Mint-19.1-Rtos.iso of=/dev/sdb conv=fdatasync status=progress

For info, files in the same dir, no need to remove original :

/remasterd/casper/initrd.lz #original
/remasterd/casper/initrd.img-5.11.4-rt11
/remasterd/casper/vmlinuz #original
/remasterd/casper/vmlinuz-5.11.4-rt11
/remasterd/casper/System.map-5.11.4-rt11
/remasterd/casper/config-5.11.4-rt11
/remasterd/casper/filesystem.squashfs

These files are still original :
/remastered/boot/grub/crub.cfg
/remastered/boot/grub/loopback.cfg
/remastered/isolinux/isolinux.cfg

Todo :

Install linuxcnc and ethercat.
Test one time more.

Second login as chroot after iso was oke.

Add linuxcnc

sudo apt-key adv --keyserver hkp://keys.gnupg.net:80 --recv-key EF1B07FEE0EE663E
sudo apt-add-repository 'deb http://buildbot.linuxcnc.org/ stretch master-rtpreempt' # or add it with echo ..
sudo apt-get update
sudo apt-get -y install linuxcnc-uspace
sudo apt-get -y install linuxcnc-uspace-dev

Add ethercat-master

apt-get install git autoconf libtool thunar

cd /home
git clone https://gitlab.com/etherlab.org/ethercat.git ethercat-master
    cd ethercat-master
    git checkout stable-1.5 
    ./bootstrap
    ./configure --help

	# error :
	# --with-linux-dir=<DIR>  Linux kernel sources [running kernel]
	# This was tricky.. The kernel headers where in the /home dir because we compiled a custom kernel over there, normal they are in /usr/src/
	# The configure script will find the headers normally in /usr/src/

    ./configure --enable-generic --disable-8139too --with-linux-dir=/home/rtlinux/linux-5.11.4/
    make
    make all modules
    make modules_install install
    # depmod 
    
    # to be sure :
	chmod 777 /etc/init.d/ethercat 

Run a script at boot time

sudo crontab -e

@reboot echo MASTER0_DEVICE="$(cat /sys/class/net/enp0s25/address)" > /etc/sysconfig/ethercat 
@reboot echo "DEVICE_MODULES=generic" >> /etc/sysconfig/ethercat 
@reboot /etc/init.d/ethercat start

Install linuxcnc-ethercat

    cd /home
git clone https://github.com/grotius-cnc/linuxcnc-ethercat.git
cd linuxcnc-ethercat
nano configure.mk
# Line 1 : COMP=/usr/bin/halcompile
make

# error : expat.h not found. I suggest we miss a library.

sudo apt-get install dctrl-tools dkms autoconf cmake make gcc build-essential debhelper
sudo apt-get install libudev-dev tcl8.6-dev tk8.6-dev libtk-img bwidget tclx8.4 asciidoc dblatex # in this line a dep is libexpat1.

make
make install

# Copy lcec.so to linuxcnc rtlib.
cp /home/linuxcnc-ethercat/src/lcec.so /usr/lib/linuxcnc/modules/

Create a configuration testfile

mkdir /home/ethercat-bus-test
cd /home/ethercat-bus-test

    touch /home/ethercat-bus-test/ethercat-conf.xml 
nano /home/ethercat-bus-test/ethercat-conf.xml 

	<masters>
	<master idx="0" appTimePeriod="15000" refClockSyncCycles="1000000">
	<slave idx="0" type="EK1100" name="Terminal"/>
	<slave idx="1" type="EL2124" name="output_stepper_1"/>
	<slave idx="2" type="EL2124" name="output_stepper_2"/>
	</master>
	</masters>
	
touch /home/ethercat-bus-test/commands.txt
nano /home/ethercat-bus-test/commands.txt

	$ halshow
	halcmd:
	> loadrt threads name1=base-thread fp1=0 period1=15000 name2=servo-thread period2=1000000
	> loadusr -W /home/linuxcnc-ethercat/src/lcec_conf /home/ethercat-bus-test/ethercat-conf.xml 
	> loadrt lcec

Done. Let's repack and test the iso.

# Repack the squashfs-root dir into a filesystem.squashfs, put the dir outside the iso folder
mksquashfs squashfs-root/ filesystem.squashfs -comp xz

# Edit /.disk/info
Linux Mint 19.1 Rtos Lcnc Ethcat

# Create iso
xorriso -as mkisofs -V 'Linux Mint 19.1 Rtos Lcnc Ethcat' \
-o Linux-Mint-19.1-Rtos-Lcnc-Ethcat.iso -J -J -joliet-long -cache-inodes \
-isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
-b isolinux/isolinux.bin \
-c isolinux/boot.cat -boot-load-size 4 -boot-info-table -no-emul-boot -eltorito-alt-boot \
-e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat -isohybrid-apm-hfsplus .

 # Copy iso to usb storage device   
 sudo dd bs=4M if=Linux-Mint-19.1-Rtos-Lcnc-Ethcat.iso of=/dev/sdb conv=fdatasync status=progress

Runtest, ok.