USB Boot Ubuntu Server 20.04 on Raspberry Pi 4

[egrechko]

Hey folks. Recently I got Ubuntu Server 20.04 to USB boot on a Raspberry Pi 4 so I wanted to post my guide on here to help some people out.

I also have a write up on my website. https://eugenegrechko.com/blog/USB-Boot ... berry-Pi-4

Update firmware to support USB Booting

First things first you need to make sure that your Raspberry Pi 4 supports USB Booting. In order to do this, you will have to install Raspbian on an SD card and update the firmware. To do this reference this video https://www.youtube.com/watch?v=tUrX9wzhygc. You'll want to watch up to the part where he verifies the boot loader is updated, around 7:56. If you already updated your bootloader skip to the next step.

Download 64 bit version of Ubuntu Server

Now we need to download the 64bit version of Ubuntu Server for Raspberry Pi 4. Then we'll flash the image to our SSD using Raspberry Pi Imager.

Visit the Ubuntu Raspberry Pi download page and grab yourself the 64-bit version for the RP4.

Flash Image to SSD

After downloading our image we'll need to install Raspberry Pi Imager. Visit the Raspberry Pi Downloads page and install it on your computer.

Next open Imager. Click "Choose OS" & find your newly downloaded image of Ubuntu Server. After that click on "Choose SD Card" and select your SSD drive. Finally, click Write and wait for the process to finish.

Mount system-boot partition on SSD

Now we need to mount the system-boot partition on the SSD drive in order to change some things.

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sudo mkdir /mnt/ssdboot
sudo mount /dev/sdb1 /mnt/ssdboot
cd /mnt/ssdboot

Uncompress the kernel

IMPORTANT: You will have to rerun this step every time ubuntu updates the kernel.

First, we're going to uncompress the vmlinuz file into vmlinux. This is because booting from a compressed 64bit arm kernel is not currently supported.

Find out where the gzipped content starts in the image.

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od -A d -t x1 vmlinuz | grep '1f 8b 08 00'

Expected output

0000000 1f 8b 08 00 00 00 00 00 02 03 ec 5b 0f 74 54 e5

The first string of numbers 0000000 is the location that we're looking for. In this case its right at the beginning of the image.

Now use dd to extract the data and zcat to uncompress it into a file. If your number was something other than 0000000 make sure you put that number as the skip value.

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dd if=vmlinuz bs=1 skip=0000000 | zcat > vmlinux

Update config.txt for booting

Now that we have the uncompressed image we'll want to update the config.txt file in order to tell the Pi how to boot.

Edit config.txt ( you can use nano or gedit if you're not comfortable with vim )

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vim config.txt

Start by commenting out all of the [pi*] blocks. Comment out the block and it's options. Should look like this.

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#[pi4]
#kernel=uboot_rpi_4.bin
#max_framebuffers=2

#[pi2]
#kernel=uboot_rpi_2.bin

#[pi3]
#kernel=uboot_rpi_3.bin

Add kernel=vmlinux & initramfs initrd.img followkernel in the [all] section. Leave the rest the way it was before.

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[all]
arm_64bit=1
device_tree_address=0x03000000
kernel=vmlinux
initramfs initrd.img followkernel

Update .dat & .elf files

Now we need to update the .dat & .elf files to the latest version in the master branch of the raspberrypi/firmware Github. https://github.com/raspberrypi/firmware ... aster/boot

Download boot folder

Visit the link above and download the folder using something like GitZip. https://gitzip.org/

Copy files from downloaded folder

Next copy all of the .dat & .elf files into the boot folder. Overwrite all files.

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cp ~/Downloads/firmware-/boot/*.dat ./

cp ~/Downloads/firmware-/boot/*.elf .

Boot

Now you're ready to boot your Raspberry Pi. Make sure the SD card is unplugged. Unmount the SSD from your computer. Plug it into your Raspberry Pi and power on.

If you run into any issues let me know. I'll do my best to help you out. Hope this helped some people!

[ranrinc]

Thanks for the guide, however I made some changes and adding jsciamms procedure into it. My guide can be read here https://krdesigns.com/articles/Boot-ras ... ut-microsd

[egrechko]

Thanks for the guide, however I made some changes and adding jsciamms procedure into it. My guide can be read here https://krdesigns.com/articles/Boot-ras ... ut-microsd

Wow, great guide. I'm going to incorporate the kernel uncompress script and a couple of other things into my Pi to see how they work. Thanks!

[esbeeb]

Hello.

I appreciate this breakthrough.

I too have come up with a simple way to gain the speed of running Ubuntu from a USB-attached SATA drive (albeit, the "system-boot" partition is still run from a MicroSD card, which is why it's "less elegant"). Please see here, for this "less-elegant" method.

It basically involves some careful labeling of a couple of partitions, to get the "writable"-labelled root filesystem to be loaded from the USB-attached SATA drive, instead of running it from the MicroSD card.

[ranrinc]

Hello.

I appreciate this breakthrough.

I too have come up with a simple way to gain the speed of running Ubuntu from a USB-attached SATA drive (albeit, the "system-boot" partition is still run from a MicroSD card, which is why it's "less elegant"). Please see here, for this "less-elegant" method.

It basically involves some careful labeling of a couple of partitions, to get the "writable"-labelled root filesystem to be loaded from the USB-attached SATA drive, instead of running it from the MicroSD card.

Yup and old method, by simply using the microSD to redirect its boot to USB Drive instead, but today the best way to do it is using this new method so we can have a better used of the microSD for something else..