Comment 7 for bug 1885663

This is my first time tracking down a kernel bug, so it's taking me a little while as I learn the bisection & kernel compilation procedure.

As an initial step, I have isolated the problem to something Ubuntu-specific. I have now tried running several mainline 5.4 kernels including, e.g., 5.4.17-050417-generic and found, to my surprise, the wireless signal is strong on those mainline kernels. To summarize my testing:
BAD:
  20.04 runs a signed Ubuntu 5.4 or 5.6 kernel
GOOD:
  18.04.4 (live usb) runs the default signed 5.3 kernel
  20.04 runs unsigned mainline 5.3, 5.4, 5.8 kernels

As a step towards a bisection, I've tried to boot a signed Ubuntu 5.3 kernel (taken from 18.04) on 20.04, but this hangs at the "Loading initial ramdisk" stage -- presumably due to some incompatibility between 18.04 and 20.04. I'll next attempt to compile the Ubuntu 5.3 kernel myself, which will hopefully boot on 20.04.