RaspiOS

Installing Raspberry Pi OS (Raspian OS)

To install RaspianOS on an SD Card and configure it, follow these instructions.

• Download the most recent 64 bit lite version of raspios from here and extract the image from the downloaded file.
• write the image to the SD Card

  sudo dd if=2024-07-04-raspios-bookworm-arm64-lite.img of=/dev/sdb bs=4M conv=fsync status=progress
  

• mount the partition "bootfs"
• In the bootfs partition create an empty file named ssh to activate the ssh server

  touch ssh
  

• Set a password for the user pi

  echo "pi:"$(echo 'password' | openssl passwd -6 -stdin) > userconf
  

• Unmount the SD card from the PC and put it into the Raspberry Pi.
• Connect the Raspberry Pi to the local LAN with a network cable and boot the device.
• Once booted the Raspberry Pi should get an IP address from the local DHCP server. Now connect to the device with

  ssh pi@raspberrypi
  

• Change the password to something better than "password"

  passwd
  

• (optional) add your public ssh key to ".ssh/authorized_keys"
• run raspi-config to configure and enable features of the Raspberry Pi

  sudo raspi-config
  

  • Set up WiFi under "System Options -> Wireless LAN" as the WiFi interface will be the main method used to connect to the openwrt-testlab. The cabled connection will be used with the attached devices.
  • Set up a hostname under "System Options -> Hostname" for example testlab01
  • Enable I2C under "Interface Options -> I2C"
  • (optional) Enable the Serial Port under "Interface Options -> Serial Port"
  • (optional) Set the localisation under "Localisation Options -> Locale" to en_US-UTF-8
  • Set the timezone under "Localisation Options -> Timezone"
  • Exit rapi-config via "Finish" and reboot (you can now remove the network cable)

Now it should be possible to log into the device with

ssh pi@hostname

where hostname is the name you used above.

Upgrade the system with:

sudo apt-get update
sudo apt-get --with-new-pkgs upgrade

reboot the system.

sudo reboot

After the reboot, remove old packages

auto apt-get autoremove

---

The Linux Kernel

Now it is time to patch and build a new linux kernel. The instructions can be found here and it is important to apply the patch 0001-sc16is7xx.c-increase-SC16IS7XX_MAX_DEVS-to-16.patch before starting the build.

• This patch is needed when more than 4 of the Serial Expansion HATs are used. With the MAX_DEVS now set to 16, up to 8 of the HATs can be used. If more are needed, adjust the MAX_DEVS accordingly.
• Read more about the Serial Expansion HAT.

sudo apt install git
git clone --depth=1 https://github.com/raspberrypi/linux
cd linux
wget -O /tmp/patch https://github.com/pmelange/openwrt-testlab/blob/main/Documentation/RaspiOS/0001-sc16is7xx.c-increase-SC16IS7XX_MAX_DEVS-to-16.patch](https://raw.githubusercontent.com/pmelange/openwrt-testlab/main/Documentation/RaspiOS/0001-sc16is7xx.c-increase-SC16IS7XX_MAX_DEVS-to-16.patch
git apply /tmp/patch
sudo apt install bc bison flex libssl-dev make
KERNEL=kernel8
make bcm2711_defconfig
CONFIG_LOCALVERSION="-v8-TESTLAB"
make -j6 Image.gz modules dtbs
sudo make -j6 modules_install
sudo cp /boot/firmware/$KERNEL.img /boot/firmware/$KERNEL-backup.img
sudo cp arch/arm64/boot/Image.gz /boot/firmware/$KERNEL.img
sudo cp arch/arm64/boot/dts/broadcom/*.dtb /boot/firmware/
sudo cp arch/arm64/boot/dts/overlays/*.dtb* /boot/firmware/overlays/
sudo cp arch/arm64/boot/dts/overlays/README /boot/firmware/overlays/

and reboot into the new kernel.