Activating USB boot for Ubuntu MATE 20.04 LTS on Raspberry Pi 4

Norbert_X · 17 July 2021 16:12

It is known that modern Ubuntu MATE 20.10 is capable to boot from USB.
If you want to upgrade 20.10 to 21.04 by sudo do-release-upgrade or update-manager -c , the resulting system will be able to boot from USB too. This is true for both 32-bit (armhf) and 64-bit (arm64).

But what is about Ubuntu MATE 20.04 LTS?

The below guide shows how to boot existing Ubuntu MATE 20.04.1 LTS from USB.

Using 32-bit armhf image

What should we do:

Install updated bootloader into RPi, see this guide for complete instruction.
Download official installation image to laptop using link https://ubuntu-mate.org/download/armhf/focal/ and write it directly to USB flash or USB SSD.

Mount system-boot partition on laptop and then replace the contents of config.txt file with the following lines from 20.10 image:

[pi4]
max_framebuffers=2

[all]
kernel=vmlinuz
cmdline=cmdline.txt
initramfs initrd.img followkernel

# 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

then unmount this system-boot partition and detach its USB storage device.

Insert USB storage device into RPi 4, power it, wait for first boot and enjoy!

Using 64-bit arm64 image

What should we do:

Install updated bootloader into RPi, see this guide for complete instruction.
Download official installation image to laptop using link https://ubuntu-mate.org/download/arm64/focal/ and write it to microSD card using USB- or internal cardreader.
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.

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

Insert microSD card to USB-cardreader, connect USB-cardreader to Raspberry Pi 4, allow it to boot, then power it off.
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.
Connect USB media to Raspberry Pi 4, boot it and enjoy!