steps to create minimalistic os for raspberrypi

minimalistic-OS-for-RaspberryPi.txt

global objectif ( create minimalistic os for raspberrypi ) :

download lite version of raspbian OS.
remove the rootfs partition and replace it with busybox root-fs
to do so you need to cross-compile busyBox for the raspberryPi
once done you just replace partition 2 with the busybox binary.




steps for installing raspbianOS standard edition in sdcard:

# 1 ) enjoy life

# 2 ) download lite version raspbianOS:
https://raspberry-pi.fr/telechargements/

# 3 ) insert sd card in computer

# 4 ) lsblk -p ## to print connected storage in computer ( disk , .. )

# 5 ) mount -l | grep "sdb1\|sdb2" # to check if they are mounted
      # 5.1 ) unmount /dev/sdb*

# 6 ) copying the image to the sd card: ( try with 1M ( MByte ) if not working )
sudo dd bs=4M if=*.img of=/dev/sdb1 conv=fsync








steps for cross compiling :

# 1 ) enjoy life

# 2 ) set up environnement variables for crossCompilation

ARCH=arm
CROSS_COMPILE=arm-linux-gnueabihf-
PATH=$PATH:$HOME/gcc-linaro-*version*-x86_64_arm-linux-gnueabihf/bin
export ARCH CROSS_COMPILE PATH

# 3 ) install gcc-arm-...
sudo apt-get install gcc-arm*

# 4 ) cross compilation busyBox

git clone https://github.com/mirror/busybox.git
git checkout
make defconfig
make -j4
make install CONFIG_PREFIX=<path>/rootfs_rpi

# 4) installation libs manquant:
Arm-linux-gnueabihf-readelf -a /bin/busybox | grep ‘\.so’






steps for current root-fs with the one we just created ( busyBox )

# 1 ) enjoy life much more

# 2 ) unmount /dev/sdb2 
# 3 ) sudo mkfs.ext4 -L rootfs /dev/sdb2 ( on format la 2eme partition)
# 4 ) on ejecte puis on reinsert la sd card
# 5 ) sudo cp -a -v <path>/rootfs_rpi/* //media/$USER/rootfs
 



step for testing :

just launch your raspberryPi










#useful links :

CoursBDRT.pdf : support du cour

https://www.raspberrypi.org/documentation/installation/installing-images/linux.md

https://books.google.fr/books?id=o9tBDwAAQBAJ&pg=PA76&lpg=PA76&dq=Make+install+CONFIG_PREFIX%3D%3Cpath%3E/rootfs_rpi&source=bl&ots=_utJYbV0ep&sig=ACfU3U1fms6Kw1NLswIN9wWPG6zrPBHlNA&hl=fr&sa=X&ved=2ahUKEwiqg-aOl_nlAhUJzoUKHaoTBOAQ6AEwAHoECAcQAQ#v=onepage&q&f=false