Ok just got around to it.. Now that were up to u4 I still went ahead and tried to run u3 just for the sake of doing it..
u3 stops with this error:
typeinfo for driver_device_config<driver_device>in sega.a(segamsys.o)
ld: symbol(s) not found
collect2: ld returned 1 exit status
make: *** [mame] Error 1
After that I did a make clean, and patched u4.
Now u4 is ending with this error:
cc1plus: warnings being treated as errors
src/mame/video/stvvdp2.c: In function ‘void saturn_vdp2_regs_w(address_space*, offs_t, UINT32, UINT32)’:
src/mame/video/stvvdp2.c:5491: warning: ‘vert_res’ may be used uninitialized in this function
src/mame/video/stvvdp2.c:5491: warning: ‘horz_res’ may be used uninitialized in this function
make: *** [obj/sdl/mame/mame/video/stvvdp2.o] Error 1
make: *** Waiting for unfinished jobs....
Everything up to and including u2 worked just perfect.. So it looks like Im at baseline 0.142 til I can figure it out hehe..