Bug 2229766

1. Please describe the problem:
I am running Fedora 38 on an old 2009 iMac. So far all versions from 36 with all upgrades and the corresponding kernel versions have behaved OK. However after upgrade of the kernel to version 6.4.7 the machine freezes during boot. I had to set the default boot kernel to be the previous version - 6.4.6. The only way to move on is to power-cycle the computer.

Update 9 August 2023: Happens with 6.4.8 too.
Update 11 August 2023: Happens with 6.4.9 too.
Update 14 August 2023: Happens with 6.4.10 too.
Update 19 August 2023: Happens with 6.4.11 too.

2. What is the Version-Release number of the kernel:
6.4.7, 6.4.8, 6.4.9, 6.4.10, 6.4.11

3. Did it work previously in Fedora? If so, what kernel version did the issue
   *first* appear?  Old kernels are available for download at
   https://koji.fedoraproject.org/koji/packageinfo?packageID=8 :
Yes and I already described -- I reverted to booting with 6.4.6

4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:
It happens every time I boot on my hardware.
Update: Same with 6.4.8 - every time I reboot.
Update: Same with 6.4.9 - every time I reboot
Update: Same with 6.4.10 - every time I reboot

* I have now officially became a grubby expert!

5. Does this problem occur with the latest Rawhide kernel? To install the
   Rawhide kernel, run ```` followed by
   ``sudo dnf update --enablerepo=rawhide kernel``:
Have not tested yet with rawhide
I cannot test with rawhide, because the Macs are with secure boot.

6. Are you running any modules that not shipped with directly Fedora's kernel?:
No

7. Please attach the kernel logs. You can get the complete kernel log
   for a boot with ``journalctl --no-hostname -k > dmesg.txt``. If the
   issue occurred on a previous boot, use the journalctl ``-b`` flag.

Impossible to attach this boot log, since the kernel freezes before anything is displayed at boot. I have no feedback whatsoever and no basis for any information. It is complete freez of the system, the exit of which is only a power-cycle.

Reproducible: Always