[coyotos-dev] coyotos.ioperm

[Jonathan S. Shapiro]

On Sat, 2007-04-07 at 00:55 +0200, Valerio Bellizzomi wrote:
> On 06/04/2007, at 11.31, Jonathan S. Shapiro wrote:

> On this architecture we have three choices:
> >
> >  1. Make I/O rights be all or nothing. This is what the EROS IOperm
> >     capability did, and what the Coyotos IOperm capability was intended
> >     to do.
> >
> >  2. Come up with a way to memory map the IO bitmap. This is the
> >     solution that I prefer, but there are complications.
> 
> Did you forget the third choice ?

Um. Yes. Use dynamic translation, and enforce the permission using the
translator.

> The main reason I asked is that we need a way to control the state of
> individual pins of the parallel port. We are currently doing this with
> fedora, but we would like to use coyotos.

I don't think that any decision about ioperms will change this. The
permissions bitmap is only going to control access to the parallel port
as a whole. If you want pin-level control, you're going to need to do
that with a software wrapper in any case. What the permissions bitmap is
going to control is the I/O permissions available to the wrapping
software.

shap