Uhm, I'm not sure I believe that's safe.
The PIT is particularly pissy in this case -- the semantics of the PIT are ill-defined if there hasn't been a PIT clock between two adjacent accesses, so I fully expect that there are chipsets out there which will do very bad things in this case.
Okay. Now that they're isolated, do you have a suggestion for {in,out}b_pit? You say a PIT clock, so do you think we can bounce of the PIT iself in this case after all?