Re: What needs doing?

[Ivan Jager]

On Sat, 19 Mar 2005, Marcus Brinkmann wrote:
> At Sat, 19 Mar 2005 14:08:14 +0100,
> Marcus Brinkmann (E-Mail) wrote:
> Something even more level, although related, is IO port spaces for
> L4Ka::Pistachio.  I think some other people may already work on that,
> but I have seen no result so far.  The trick here is getting something
> implemented that is acceptable to the L4 people, so you are aiming at
> high performance and get to hack the kernel.

Hmm, this sounds interesting. I had thought it was already implemented. Do 
you know how long they've been working on it?

> The way how to implement I/O spaces efficiently on the ia32
> architecture is explained in some mail in the l4ka mailing list
> archive, I can dig it up for you if you are interested.  There was an
> implementation of something like that in an older L4 kernel (Fiasco?),
> so you would not hang in the air there.

Yes, could you dig it up please?

> Currently, L4 just allows all tasks to access I/O ports, which is not
> acceptable from a security point of view.

Ouch! Doesn't that make everything that runs on L4 insecure, including 
L4Linux and DROPS?

> At the high level side, you could also tinker with exception handling.
> Basically, fix up the exception handling in L4 (maybe you can press
> the L4 people to push their changes into the public tree if they
> already addressed that) and look into writing a user space exception
> handler that can serve as a base for future implementation of the
> signal handler.
>
> Somewhat related to that: User space debugging.

I think we'll stay away from this one...


Ivan