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Re: What needs doing?

From: Ivan Jager
Subject: Re: What needs doing?
Date: Mon, 21 Mar 2005 02:59:20 -0500 (EST)

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...


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