Ubuntu 20.04.5 Focal Fossa USB Boot

Using 64-bit arm64 image

What should we do:

1. Install updated bootloader into RPi, see this guide 51 for complete instruction.

2. Download official installation image to laptop using link https://ubuntu-mate.org/download/arm64/focal/ 14 and write it to microSD card using USB- or internal cardreader.

3. Boot Raspberry Pi 4 using microSD card as usual: choose locale, create user, reboot, login to system, then install all updates and do cleanup by sudo apt update && sudo apt dist-upgrade -y && sudo apt autopurge -y && sudo apt clean -y, reboot to ensure that system on microSD is fully functional, poweroff the Raspberry Pi 4.

4. Connect microSD card to laptop, mount system-boot on laptop and then replace the contents of config.txt file with the following lines:

[pi4]

max_framebuffers=2

[all]

arm_64bit=1

# kernel=uboot_rpi_4.bin

kernel=vmlinuz

cmdline=cmdline.txt

initramfs initrd.img followkernel

# device_tree_address=0x03000000

# enable_uart=0

# Enable the audio output, I2C and SPI interfaces on the GPIO header

dtparam=audio=on

dtparam=i2c_arm=on

dtparam=spi=on

# Enable the FKMS ("Fake" KMS) graphics overlay, enable the camera firmware

# and allocate 128Mb to the GPU memory

dtoverlay=vc4-fkms-v3d

gpu_mem=128

start_x=1

# Comment out the following line if the edges of the desktop appear outside

# the edges of your display

disable_overscan=1

# If you have issues with audio, you may try uncommenting the following line

# which forces the HDMI output into HDMI mode instead of DVI (which doesn't

# support audio output)

#hdmi_drive=2

# If you have a CM4, uncomment the following line to enable the USB2 outputs

# on the IO board (assuming your CM4 is plugged into such a board)

#dtoverlay=dwc2,dr_mode=host

5. Insert microSD card to USB-cardreader, connect USB-cardreader to Raspberry Pi 4, allow it to boot, then power it off.

6. Copy the whole microSD card to USB-flash or USB SSD, optionally grow the size of writable partition to fit free space of USB media.

7. Connect USB media to Raspberry Pi 4, boot it and enjoy!