> On 25th Oct, Todd Whitesel wrote:
> >       root file system type: ffs
> >       panic: Prefetch abort in non-USR mode (frame=0xf35a8d44)
> > 
> >       Stopped in init at      _Debugger+0x10: ldmdb   r11, {r11, r13, r15}
> >       db>
> > 
> > if I type "trace" I get
> > 
> >       db>trace
> >       _Debugger(_Debugger+0x10)
> >       _panic(_panic+0x14)
> >       _prefetch_abort_handler(_prefetch_abort_handler+0x10)
> >       _cnopen(_cnopen+0x10)
> >       _spec_open(_spec_open+0x10)
> >       _vn_open(_vn_open+0x10)
> >       _sys_open(_sys_open+0x10)
> >       _syscall(_syscall+0x10)
> >       db>
> 
> I get a very similar output with a fresh -current (and Richard
> Earnshaws wdc patch). The wdc patch made the machine recognise the
> discs, but then I got a panic. However, I've got _resethandler instead
> of _prefetch_abort_handler in the above list.
> 
> Also, I've got:
> 
> panic: Branch to never-never land (zero)..... were (sic) dead
> prior to the above.

Hmm, I saw a "Branch to never-never..." while I was testing the above 
patch; but since at the time other things weren't working (it wasn't 
taking interrupts at that time), I assumed the two were related.  Perhaps 
this is a race condition somewhere.  I haven't rebooted it more than once 
since I managed to get things working.

It looks to me as though cdevsw[major(dev)].d_open in dev/cons.c is a NULL 
(or nearly NULL) pointer.

Richard.