Re: Mach on L4

[Michael Hohmuth]

Farid Hajji <address@hidden> writes:

> > [...]  I envision more of a portability layer with an interface
> > similar to that of the Linux kernel's architecture-dependent part
> > (although hopefully a bit cleaner).  Let's call this KAL
> > (``kernel-abstraction layer'') for a moment.
[...]
> As a *BSD-guy, I'm not very familiar with Linux internals, so I'll
> have to figure out what you mean with "architecture-dependent part"
> by diving in Linux's sources ;-). I'm acquainted to FreeBSD und NetBSD
> internals though, so I can roughly imagine what you mean here.

To get the general idea, have a look at
<URL:http://os.inf.tu-dresden.de/~hohmuth/prj/linux-on-l4/if/>
(Postscript version at
<URL:http://os.inf.tu-dresden.de/~hohmuth/prj/linux-on-l4/if.ps.gz>).
In that report, I documented part of Linux' architecture-adaption
layer's interface.  (The report corresponds to an ancient version of
Linux, but it should be enough to give you the idea.)  Yes, I guess
that it is similar to the BSDs' portability layer's interface.

> > - Don't assume your basic RPC mechanism can transfer system-object handles 
> >   (handles for threads, address spaces, etc.).
> I understand the rationale behind this. It seems like this will be quite
> hard to enforce though. Okay, I'll try to come up with a basic model.
> I'd need help here though (suggestions, ideas, etc.)...

Your KAL interface doesn't have to have the same restriction, as long
as a KAL implementation can deal with the issue internally.

> ~/.plan: pondering about the first practical steps of Hurd refactoring,
> then getting back to l4-hurd with a proposal-draft.

Good luck,
Michael
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