Re: A comment about changing kernels

[Neal H. Walfield]

At Fri, 28 Oct 2005 20:34:09 +0200,
Bernhard Kauer wrote:
> 
> > The problem with L4.sec is the following: It does currently not have
> > all the operations that we think we need (I am thinking specifically
> > about efficient capability copy and identification). 
> 
> Just some comments from the L4.sec perspective:
> 
> The identification via read_badge() is something which will in my
> opinion be part of the kernel if we do not come with a better solution
> to solve the multiple capability-parameters problem. Since the read_badge()
> operation could change, it is currently called "experimental" in the spec.
> 
> Now to copy(): I know no functional argument to introduce a copy() into
> L4.sec.

Have you considered this argument [1]?  I'd be interested in hearing
the reactions from the L4.sec perspective.

> The only argument is performance. Because mapping (or copy) a
> return endpoint with every RPC will be too expensive, server protocols
> will be session based. To establish a new session with a server the
> server has to be called anyway, which nullifies the advantage of copy().

I don't understand this.  Could you please elaborate what "server
protocols will be session based" means?  Perhaps with an illustration
of what you envision?

> Beside this, both operations are implementable with around 30 lines of
> code each, which makes these features not very critical.

Which features do you mean exactly?

Thanks,
Neal


[1] http://lists.gnu.org/archive/html/l4-hurd/2005-10/msg00361.html