Hi,
I examined this problem of GENERIC kernel on my RPI2B-1.2 a little
bit further.
It seems that WSDISPLAY_MULTICONS (enabled in GENERIC, disabled in
RPI*) does not work on machines that use plcom0 as console.
GENERIC kernel works on RPI2B-1.2 if 'console=fb' is not specified
in cmdline.txt, or 'console=fb' is specified but WSDISPLAY_MULTICONS
is disabled. RPI2 kernel also hangs if 'console=fb' is specified and
WSDISPLAY_MULTICONS is enabled.
Also for RPI0W, RPI kernel hangs if 'console=fb' is specified and
WSDISPLAY_MULTICONS is enabled.