"Eli Gottlieb" wrote in message
...
Olumide wrote:
Hi -

I know memory mapped IO is about mapping device/controller registers to
memory space in order to reduce the number of processor instructions
(and simplify device driver writing) . My question is: are device
registers mapped to virtual memory or physical memory? I suspect the
former, and I have looked up a number of texts but everyone just seems
to skirt about the issue.

Thanks,

- Olumide

Device registers have a "physical" address that can be mapped into virtual
memory using normal paging techniques, AFAIK.

Correct for real, physical devices in non-virtualized environments. If we go
for virtual ones, we may never know what is real and what is emulated in
some way (e.g. a page fault handler would do the emulation).

Alex