A lot of drivers refuse to start roughly after r25388 "New AM_(DEV)SETOFFSET feature for address maps" commit, like so:

Driver dendy (file nes.c): 3 errors, 0 warnings
Errors:
generic space memory map entry 0-FFFFFFFF references non-existant region ''
N2A03 device ':maincpu': program space memory map entry 0-7FF references non-existant region ''
2C07 PPU device ':ppu': videoram space memory map entry 0-3EFF references non-existant region ''