Comment # 12 on bug 1189762 from Dainius Masiliunas

Created attachment 852085 [details]
Screencap of earlycon=efifb keep_bootcon

Success! Of course, earlyprintk=efi doesn't work because it was removed in
kernel 5.1; but instead, using earlycon=efifb and keep_bootcon gives me an
output. It shows me that the kernel is stuck in a loop with "bad: scheduling
from the idle thread!" and a stack trace. See attached screencap. There is a
bit of an overlap due to screen refresh, but it loops, so you can see the same
repeated twice on each screen.