Comment 22 for bug 1844784

Thanks! This definitely seems to be related to secure boot, but not lockdown (which gets enabled automatically when booted under secure boot). I'll try following that lead and see what I can find.

The other thing which might still help is testing the kernel from comment #17 with secure boot enabled, to see if we can get the oops message captured in persistent storage. This means generating your own MOK with the correct extendedKeyUsage, enrolling it with shim, and signing the kernel with that key. If you're up for it, instructions are here:

https://ubuntu.com/blog/how-to-sign-things-for-secure-boot

Just be sure to read the section under "Enrolling the key" before actually generating your keys, which notes that you need to remove an OID from extendedKeyUsage if you want to use the key for signing kernels.