Fiasco.OC x86 IO port permission bitmap

Daniel Waddington d.waddington at
Fri Jan 27 22:38:39 CET 2012

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


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
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