Ubuntu 24.04 won't boot with bcm2712-rpi-cm5l-cm5io.dtb

[jstockdale]

---

name: Ubuntu 24.04 won't boot with bcm2712-rpi-cm5l-cm5io.dtb
about: After updating overlay to "cm5l" specific dtb, device fails to boot

---

Describe the bug
I was previously using the CM5 dtb overlay from the CM5 (where I added the Lite model to the supported device list in app.db), that works great. It boots. Everything is happy. After apt update and apt upgrade I saw failures to recompile initramfs due to the bcm2712-rpi-cm5l-cm5io.dtb missing. I added this file and now my system won't boot.

To reproduce
Take a working Ubuntu 24.04 CM5 image, and try to boot it with bcm2712-rpi-cm5l-cm5io.dtb – this new overlay breaks Ubuntu.

Expected behaviour
Ubuntu 24.04 should boot with bcm2712-rpi-cm5l-cm5io.dtb

Actual behaviour
Device goes to Ubuntu boot screen and hangs. Eventually boots to busybox.

System
Copy and paste the results of the raspinfo command in to this section. Alternatively, copy and paste a pastebin link, or add answers to the following questions:

• Which model of Raspberry Pi? Raspberry Pi CM5 Lite 16GB
• Which OS and version (cat /etc/rpi-issue)? Ubuntu 24.04
• Which firmware version (vcgencmd version)? Latest (June 20th)
• Which kernel version (uname -a)? I'll check once I can boot again.

Logs
Not available

Additional context
Add any other relevant context for the problem.

[jstockdale]

Ok it turns out I was using the bcm2712-rpi-cm5-cm5io.dtb overlay, and everything just works (except the sd card since it's probably not wired up). I got my system to use that overlay by adding a line to the CM5 entry in all.db in /etc/flash-kernel/db/all.db

Sorry for the error in my explanation it's been a while since I set this all up. I went ahead and edited the original report for clarity.

Anyway, needing to use the cm5 overlay monkey patched to load for the cm5 lite Model is probably why the sd card won't work on my image, so I'd love to get the cm5l working properly. Thanks for looking at this folks! Happy to provide more details if helpful.

[jstockdale]

Anyone? I'll dig into this and git blame or happily decompile the dtbs and look at what differences there are. But it's pretty disappointing to have a new dtb released into the wild without any support, that seems to break things. Would love any thoughts if folks have them!

[pelwell]

From your previous comment it sounded like things were working. Try:

1. understanding the difference between a base DT file (.dtb) and an overlay (.dtbo), and
2. using RPiOS - if that works, complain to Ubuntu.

[jstockdale]

Thanks for chiming in. Yes I understand the functional difference between dtb and dtbo files but didn’t realize they weren’t both called hardware overlays. Appreciate the clarity.  RPiOS boots fine on the device. How do I tell which dtb + overlay(s) RPiOS is using? Cheers!

[pelwell]

sudo vclog -m will show the file that the firmware has loaded, but I can tell you that, unless you've added a specific device_tree=... directive in config.txt, it will try to load bcm2712-rpi-cm5-cm5io.dtb on a CM5, only choosing something else if that is absent.