> 1) why does idsptch do an absolute call to 0x12345678 
>    (line 122 in arch/vax/vax/subr.s)
> 
This code is copied in whenever a device is found and an interrupt
vector is to be used. This code matches struct ivec_dsp in trap.h.
0x12345678 is modified to the device interrupt handler routine.
See around line 130 in mba/mba.c for an example.

> 2) how does build boot.mop?  It looks like the right
>    stuff is in arch/vax/boot but boot doesn't seem to
>    be boot.mop.
> 
mopa.out boot boot.mop :-) 
It doesn't build by magic; mopd understands vax a.out format anyway so
it's not normally needed.

> 3) should -current build a kernel without having to
>    fix files.vax and a few other files (ka410.c and
>    conf.c)?
> 
Yes, it should. I'm sometimes lazy I think :-)

-- Ragge