Lack of C&C redirection?

Jacob Gorm Hansen jg at
Fri Sep 27 10:38:22 CEST 2002

On Fri, Sep 27, 2002 at 09:46:49AM +1000, Gernot Heiser wrote:
> >>>>> On Thu, 26 Sep 2002 13:37:56 +0200, Jacob Gorm Hansen <jg at> said:
> JGH> Hi,
> JGH> the Fiasco website says that nobody ever implemented C&C redirection for
> JGH> L4. Is this planned?
> If the Fiasco website says that then it's ill-informed (better fix
> that, Micha). L4/MIPS had it working since the first release (see
> However, the forthcoming L4 API does away with C&C.

OK. What I am trying to do is detect if a l4linux process has changed
its task number, which it sometimes does in my setup.

What we have is a modified version of l4linux, with the following

1) Multiple instances run atop a HAL made with OSKit.

2) L4linuxes may suspend and migrate to other physical host.

This work fine, but only as long as I stick to the same task numbers
across migrations. I need to be able to detect if a task is trying to
perform out-of-clan ipc, so that either it's chief or the task itself
(upon receival of an error code from the ipc call) may take appropriate
action (recalc the dest id and retry).

If the stale dest id point to a non-existing task, I get error 0x10,
which is fine, but what happens (in Fiasco) if the task exists, just in
some other clan?

Any input welcome.


> Gernot
> --
> Gernot Heiser                        School of Computer Sci. & Engin.
> Professor of Operating Systems       The University of NSW
> Phone: +61 2 9385 5156               UNSW SYDNEY NSW 2052, Australia
> Fax:   +61 2 9385 5533     

More information about the l4-hackers mailing list