How uConsole CM4 OS Image Is Made

This guide explains how to create an OS image for the uConsole CM4 module. Since the uConsole and DevTerm share the same mainboard, the process involves adapting the DevTerm CM4 OS image with updates specific to the uConsole, such as a new kernel for its LCD screen.

Base OS Image

The base OS image used is the DevTerm CM4 image:

Download the base image:
DevTerm_CM4_v0.1a_64bit.img.bz2
md5sum: 4d990ec702d0b6383f6e43bbeb3e3274

For detailed instructions on creating the base image from scratch, refer to:
Create DevTerm CM4 OS Image from Scratch.

Kernel Update

To update the kernel for the uConsole CM4:

Use the kernel files located here:
uConsole Kernel for CM4
Create a .deb package for the kernel:
uconsole_kernel_cm4-rpi is built from the compiled output files.

Ensure the correct configuration in the config.txt file. Below is an example configuration:

disable_overscan=1
dtparam=audio=on

[pi4]
max_framebuffers=2

[all]
ignore_lcd=1
dtoverlay=dwc2,dr_mode=host
dtoverlay=vc4-kms-v3d-pi4,cma-384
dtoverlay=devterm-pmu
dtoverlay=devterm-panel-uc
dtoverlay=devterm-misc
dtoverlay=audremap,pins_12_13

dtparam=spi=on
gpio=10=ip,np

Key line:
dtoverlay=devterm-panel-uc (This sets the panel configuration specific to the uConsole.)

Chroot Environment

To modify the image in a chroot environment:

Mount the image:

sudo mkdir -p /mnt/p1
sudo losetup --show -f -P DevTerm_CM4_v0.1a_64bit.img # Assume loop0
sudo mount /dev/loop0p2 /mnt/p1
sudo mount /dev/loop0p1 /mnt/p1/boot

Set up the chroot environment:

cd /mnt/p1
sudo mount --bind /dev dev/
sudo mount --bind /sys sys/
sudo mount --bind /proc proc/
sudo mount --bind /dev/pts dev/pts
sudo chroot .

Inside the chroot environment:

Update the system and kernel:

sudo apt update
sudo apt install -y uconsole-kernel-cm4-rpi

Install additional software (games, emulators, and utilities):

sudo apt install -y devterm-tic80-cpi uconsole-love2d retroarch dosbox \
devterm-cavestory-cpi-cm4 uconsole-liko12 uconsole-lowresnx \
uconsole-dosbox-staging pppoe uconsole-4g-util-cm4

Configure the 4G extension module (optional):

sudo bash -c 'cat << EOF > /etc/modprobe.d/blacklist-qmi.conf
blacklist qmi_wwan
blacklist cdc_wdm
EOF'

Remove unnecessary software (e.g., thermal printer utilities, as uConsole does not include a thermal printer):
```
sudo apt remove devterm-thermal-printer devterm-thermal-printer-cm4
```

Perform pre-configurations:

cd /usr/local/bin/
git clone -b uconsole-cm4 https://github.com/cuu/skel.git
cp -rf skel/etc/xdg/autostart/first-touch.desktop /etc/xdg/autostart/
cp -rf skel/usr/local/bin/chgpas.sh /usr/local/bin/

Clean up old screen rotation settings (the new kernel already handles screen rotation):

nano /boot/cmdline.txt  # Remove "fbcon=rotate:1"
rm -rf /etc/X11/Xsession.d/90custom_xrandr
rm -rf /etc/lightdm/setup.sh
nano /etc/lightdm/lightdm.conf  # Comment out or delete the line:
# greeter-setup-script=/etc/lightdm/setup.sh

Exit the chroot environment:
```
exit
```

Clean Chroot Environment

After finishing work in the chroot environment, clean up:

cd -
sudo umount /mnt/p1/dev/pts
sudo umount /mnt/p1/dev
sudo umount /mnt/p1/proc
sudo umount /mnt/p1/sys

# Clear bash history
sudo rm -rf /mnt/p1/root/.bash_history

sudo umount /mnt/p1/boot
sudo umount /mnt/p1
sudo losetup -D /dev/loop0

Notes

All official uConsole OS images can be found here:
uConsole Images Repository

uConsole_CM4_v2.0_64bit.img.7z

Since v2.0, cm4 os image is made by pi-gen

just clone pi-gen repo, branch uconsole_arm64

run sudo ./build.sh in ubuntu linux PC

kernel source: 9a1e3adc9d here is kernel compiling commands:

export KERNEL=kernel8
export ARCH=arm64
export CROSS_COMPILE=aarch64-linux-gnu-

make bcm2711_defconfig

make -j4

mkdir -p ../modules
rm -rf ../modules/*

INSTALL_MOD_PATH=../modules make modules_install

mkdir -p ../firmware
rm -rf ../firmware/*
mkdir -p ../firmware/overlays

cp arch/arm64/boot/Image ../firmware/$KERNEL.img
cp arch/arm64/boot/dts/broadcom/*.dtb ../firmware
cp arch/arm64/boot/dts/overlays/*.dtb* ../firmware/overlays/
cp arch/arm64/boot/dts/overlays/README ../firmware/overlays/

KERNEL_VER=$(make kernelrelease)
cp arch/arm64/boot/Image.gz ../vmlinuz-${KERNEL_VER}

cp System.map  ../System.map-${KERNEL_VER}
cp .config  ../config-${KERNEL_VER}

mkdir -p ../linux-headers-${KERNEL_VER}

make headers_install INSTALL_HDR_PATH=../linux-headers-${KERNEL_VER}

Happy hacking!

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