> 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?

If you want to work on this with a user process, you have to make it
run in root privillege, open /dev/kmem (or was it /dev/mem), and mmap
it to access the raw physical address space. 

ken