Fiasco.OC x86 IO port permission bitmap

Adam Lackorzynski adam at
Wed Jan 25 14:29:27 CET 2012


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                 adam at

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