Ubuntu 25.10 on Snapdragon 8cx Gen 3

[shengzikun]

Okay, after I switched to installing 25.10, selecting the installation in GRUB gave an error saying “mount: mounting efivarfs on /sys/firmware/efi/efivars failed: Operation not supported” ?

[Norm24]

Maybe take a look in this thread?Not sure if it will offer the info you need but might still be worth taking a look.

FAQ: Ubuntu 25.04 on Snapdragon X Elite

Hi, for booting el2 you need the stubble.dtb_override=false option in the kernel cmdline. This prefers the externally given dtb even if a match is found in the stubble space (which is wrong for EL2).

[glathe]

Hmm interesting. I took a look into the stubble repo (and into my fork of it), and the Matebook E Go should boot with it. So maybe it is a bug (not unheard of) or the hwid was too new (08/10/25) to be in the 6.17.0-8 kernel. The way around it would be to get a newer image (or that from 25.10 maybe?) and try with this, or explicit assignment of the dtb.
For reference, the X13s and the Windows Dev Kit 2023 (also sc8280xp machines) do boot with the 25.04 image. And my newer-ish kernels should boot with it, too.