Comment # 10 on bug 1189762 from Dainius Masiliunas

Created attachment 852078 [details]
Screencap of earlycon=efifb output

I now tried with earlycon=efifb, and that gives output! It seems that it works
correctly all the way until the earlycon gets disabled and the regular console
gets enabled. I also tried with both earlycon=efifb and nomodeset, and the
result is the same except that there is an extra warning that this means the
graphics drivers will be disabled. So I guess this is in some way related to
amdgpu, then?