I recently upgraded Ubuntu from 24.10 to 25.04 on my iMac 15,1 (which is configured as single boot Ubuntu).
The new kernels 6.14.0-*-generic do not boot. After “loading initial ramdisk…” nothing visibly happens.
The older kernel 6.11.0-26-generic still works.
I tried Boot Repair (latest version, with wired network connection) to no avail.
I also tried the UEFI firmware option on the Boot Repair disk/stick, but that gave me “command fwsetup not found”.
Any help would be appreciated.
There is a bug report for that issue: Bug #2105402 “Plucky fails to boot on (older) Macs” : Bugs : linux package : Ubuntu
A kernel that boots is in the proposed repository (see the bug comments) so should be released soon.
Thanks! Apparently I managed to miss that bug report. It is not in the Plucky release notes BTW.
The fix just rolled out as an SRU. The three older Macs I had a problem with are all booting and running Plucky now!
Questing inherited the bad patch however and is still not working. I just submitted a bug for that.