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Re: A Framework for Device Drivers in Microkernel Operating Systems
From: |
Jonathan S. Shapiro |
Subject: |
Re: A Framework for Device Drivers in Microkernel Operating Systems |
Date: |
Mon, 15 May 2006 15:59:32 -0400 |
On Mon, 2006-05-15 at 20:29 +0200, Espen Skoglund wrote:
> [Tom Bachmann]
> > I did just have a short look at it, but in section 3.1 you state
> > "L4KA's main eatures are simplicity, speed and *security*.". The
> > last is wrong. I would not call global names and unprotected IPC
> > secure.
>
> Just some comments:
>
> o L4Ka is a widely defined project that encompasses many
> sub-projects. One of these sub-projects is the L4Ka::Pistachio
> microkernel. If you want to refer to features such as those above
> you should really refer to specific microkernel APIs instead.
>
> o Regarding unprotected IPCs. The IPC mechanism in Version X.2 is
> not completely unprotected. You do have the Redirectors that can
> be used for restricting IPCs, albeit not very efficiently.
>
> o The problems with global name spaces are being addressed in L4Ka
> and local name spaces have been implemented in L4Ka::Pistachio.
These three points are all true, but they demonstrate that there is no
such thing as L4. There are only N different implementations sharing
not-clearly-defined portions of a specification. Because of this, it is
difficult to understand which subsystems run on which kernel versions.
It is *impossible* to understand (or substantiate) security claims for
L4 as a whole.
Meta-comment, not really related to my statement above: it is a flaw of
the L4 specification that error behavior is underspecified.
shap
- A Framework for Device Drivers in Microkernel Operating Systems, William Grim, 2006/05/12
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Tom Bachmann, 2006/05/12
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Espen Skoglund, 2006/05/15
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Tom Bachmann, 2006/05/15
- Re: A Framework for Device Drivers in Microkernel Operating Systems,
Jonathan S. Shapiro <=
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Espen Skoglund, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Jonathan S. Shapiro, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Espen Skoglund, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Jonathan S. Shapiro, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Espen Skoglund, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Jonathan S. Shapiro, 2006/05/15
- Re: A Framework for Device Drivers in Microkernel Operating Systems, William Grim, 2006/05/15
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Tom Bachmann, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Espen Skoglund, 2006/05/16
- Re: A Framework for Device Drivers in Microkernel Operating Systems, Jonathan S. Shapiro, 2006/05/16