Booting from a Ubuntu .img file

Sep 21, 2018 3 Replies
N

Out of interest, I'm trying out Ubuntu on my Raspberry Pi 3B+.



I've downloaded the image from

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specifically
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I've copied this file to the Pi running Raspian and confirmed that sha256sum produces a checksum which matches the published one - I wasn't confident since the download stalled overnight and I had to resume it where it left off. And on a 2 Mbps connection (yuk!) I wasn't keen to start it all over again. 1.2 GB at 2 Mbps takes about 2 hours.



I've expanded the .img.xz file to .img using 7Zip on Windows 7 and then used both Rufus and W32 Disk Imager on Windows and ddrescue on Raspian to write this image to a 32 GB SanDisk Ultra micro SD card. Using W32 Disk Imager I've also verified that the SD card and the .img file match.



But when I try to boot from that SD card (replacing the Raspian card in the Raspberry Pi) it stays on the multi-coloured spectrum screen, with a lightning symbol in the top right hand corner. I've checked and the 5V power rail on the GPIO connector is 5.05 V - so it's a false alarm. The power light flashes: 4 long flashes, 4 short flashes - repeatedly. It seems that a blinking power light (red) indicates a PSU problem. but it's 2.5A, certified for RPi, and as I say, the measured voltage is just over 5V. And it boots fine to Raspian on another identical make/model of card.



Any suggestions? Is it some sort of incompatibility between an image that is said to be good for RP2 and RP3, and my RP3 B+?



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A

Possibly. At least when I recently popped a working SD card from a Pi 3 and tried to boot it in a 3B+ it didn't boot. I grabbed a Raspbian image and went with that instead.

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N

I've done a bi of research and it seems that boot images for the RP3B and RP3B+ are not necessarily compatible with each other. There's a long thread where people say "try this" and "Google is your friend" without giving any precise instructions. If someone is going to make a "try" suggestion, they need to be prepared to give instructions or a link to a precise set of instructions that have worked for someone else.

I was only trying it out of curiosity, so I won't persist until an official image for the RP3B+ is released - or exact step-by-step instructions are given for how to convert an older image to work.

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T

My guess is the image predates the 3B+, and you need to upgrade the firmware.

If you have another Pi, you can boot the image there and run rpi-update. Otherwise...

Plug the SD card into your PC and the FAT partition should open. Then go to here:

formatting link
and download the *.elf, *.dat, *.bin files to replace the ones on your SD card. Make sure the names are exactly the same (including case).

I don't know if there's a .dtb file on the SD card, but if so replace it with the bcm2710-rpi-3-b-plus.dtb one from github.

Theo

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