>
>  > how about 32-bit PCI controllers on >=4GB memory?
>  >
>  > such powerfull system is likely to have 4GB of RAM or more.
>
> Bounce buffers.  Hooray.  (I would suspect that most high-performance
> systems that can support > 4GB RAM would also have PCI devices which
> can do 64-bit addressing...)
>
mostly. but some of them may be 32-bit.