Finally I succeded in building -current and was even able to boot into
single-user mode. I tried to make the kernel smaller so I set 

makeoptions CC="cc -m68030"

and commented out (I have IIcx)

options         M68040
options         M68020          # Must have 68851 PMMU

After that the reboot command says
... kernel security level changed ...
... syncing ...
... PRAM ...

and the machine hangs. It neither halts nor reboots, the screen
becomes dark and it does not respond to NMI buttom. I had to press
reboot button to wake it up. It still respond properly to halt
command.

When I tried to enable M68020 and M68040 but not -m68030 switch
locore.s would not compile, the assembler complains about pflush
instruction. I do not insist on combining -m68030 switch with M68020
option. 

So, here is my question:

what options among 

options         M68040
options         M68030
options         M68020          # Must have 68851 PMMU
options         FPSP
options         FPU_EMULATE

are really options and what options must always be present? I remember
some time ago I got a nice song out my Mac when I disabled floating
point options and tried to reboot.

	Taras Ivanenko.