> > > But I have a weird problem : I can't access to the ATA hardware
> > > registers. Base address for these registers under macos is 50f1a000,
> > > so I try to access to them from IOBase+1a000. The point is that
> > > any read or write access to them cause an unexpected trap, always
> > > the same for a given kernel binary.
> > 
> > Sorry, this may be a dumb question, but you're not trying to access
> > I/O region from a user process, are you?
>
> It's no so dumb, and has to be asked. But no, I already heard about
> things like "memory protection" :-) Having the Tanenbaum on oses lying
> next to my bed has something to do with that ;-) Anyway it would be
> difficult for me to do that, since the kernel don't boot and don't even
> know how to talk with the keyboard.
> 
> I do that within the call to my driver function ideprobe() done by the
> kernel at boot time (major number 7 in block mode, 18 in char mode if
> you want to know :-) when trying to find its root drive (ROOT_SCSI_ID
> became BOOTDEV - had to hack noth in the booter and the kernel for that).

What particular machine are you using?  
What are the details of the `unexpected trap'? 
Are you tracking/using -current?

d
-- 
David Leonard                            Project Officer, DSTC
The University of Queensland             david.leonard@dstc.edu.au
http://www.dstc.edu.au/WP/staff/david-leonard.html