> > 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).

  Sarayan