After further experimentation and learning - I can confirm it does work as you say (at least on x86 32bit).

Daniel

On 01/25/2012 05:29 AM, Adam Lackorzynski wrote: 
Hi,

On Tue Jan 24, 2012 at 13:12:03 -0800, Daniel Waddington wrote:

I see. So it seems that you have to map all of the IO port space
before getting IOPL raised to 3 (assuming Kconfig IO_PROT &
!IO_PROT_3) and therefore the default mode of operation is a driver
will map the whole space if it wants to use IO instructions
directly.  Is it right that you currently don't use the TSS IO
bitmap to allow access to only specific IO ports with CPL > IOPL?

'in' and 'out' are supposed to work just fine on single ports, no need
to request all 64k ports for that and no iopl3 required.



Adam