Ubuntu-Mate fails to boot on Raspberry-Pi 3 via USB

Question

we are trying to use Ubuntu Mate 16.04.2 on a Raspberry Pi 3 that boots via USB(the Pi 3 has a boot bit that has been set correctly) without a sd card in place.

Hardware: Raspberry Pi 3 (Model B v1.2), Pi Desktop(Rev03, USB to msata) and a KingSpec 64Gb mSata drive.

We have tested the Raspbian stretch image (3/13/2018) and it boots(and runs) from a USB without a sd card in place. Ubuntu Mate will boot fine from a imaged sd card but not a imaged USB drive(when no sd card is present.) There is drop box note about imaging a USB drive with Ubuntu Mate, reformatting the boot partition as a FAT32, coping the original boot partition files back to the FAT32 boot partition and changing the cmdline.txt file to have a different "root=" value:

https://www.dropbox.com/s/y1wgjd32npfsqif/RUN%20UBUNTU-MATE%20FROM%20USB.txt?dl=0

Unfortunately this did not work and I currently do not see anything happening on the screen when trying to boot that would give me a clue as to what the issue is. Are there any suggestions as to what we could try next or maybe how to get a hold of a bleeding edge image of Ubuntu Mate.

Thanks.

Answer 1

Here is the long thread of how I got this to work here:

www.raspberrypi.org/forums/

Summary answer of the thread(it should be noted that the only way I got this to work on a Windows PC was by having a virtual machine running Ubuntu 14.04 so I could copy and edit files):

A 2018-03-13-raspbian-stretch.img file to a USB stick(I did this via Win32DskImager.) A ubuntu-mate-16.04.2-desktop-armhf-raspberry-pi.img to a USB stick(I did this via Win32DskImager.)

Using a Ubuntu 14.04 virtual machine mount both USB drives. You should see four disks: PI_BOOT, PI_ROOT, boot and rootfs.

Run the following commands for copying files(you will need to change the "john" portion of the path to match the location on your virtual machine):

sudo cp -r /media/john/rootfs/lib/modules/4.9.80+ /media/john/PI_ROOT/lib/modules/
sudo cp -r /media/john/rootfs/lib/modules/4.9.80-v7+ /media/john/PI_ROOT/lib/modules/
sudo cp /media/john/rootfs/lib/firmware/brcm/brcmfmac43455-sdio.txt /media/john/PI_ROOT/lib/firmware/brcm
sudo cp /media/john/rootfs/lib/firmware/brcm/brcmfmac43455-sdio.clm_blob /media/john/PI_ROOT/lib/firmware/brcm
sudo cp /media/john/rootfs/lib/firmware/brcm/brcmfmac43455-sdio.bin /media/john/PI_ROOT/lib/firmware/brcm

sudo cp /media/john/boot/bootcode.bin /media/john/PI_BOOT
sudo cp /media/john/boot/fixup.dat /media/john/PI_BOOT
sudo cp /media/john/boot/start.elf /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2710-rpi-3-b-plus.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/kernel.img /media/john/PI_BOOT
sudo cp /media/john/boot/kernel7.img /media/john/PI_BOOT

I'm not positive that these files are necessary...

sudo cp /media/john/boot/bcm2708-rpi-0-w.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2708-rpi-b.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2708-rpi-b-plus.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2708-rpi-cm.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2709-rpi-2-b.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2710-rpi-3-b.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2710-rpi-3-b-plus.dtb /media/john/PI_BOOT
sudo cp /media/john/boot/bcm2710-rpi-cm3.dtb /media/john/PI_BOOT

To edit the next files you need to be super user so launch gedit from the command line with

sudo gedit

From gedit change the /media/john/PI_BOOT/cmdline.txt file so that root=/dev/sda2

From gedit change the /media/john/PI_ROOT/etc/fstab file to:

proc /proc proc defaults 0 0
/dev/sda2 / ext4 defaults,noatime 0 1
/dev/sda1 /boot vfat defaults 0 2

Unmount the drives from the virtual machine and place the Ubuntu Mate USB in the Pi 3 and boot.