Re: thread ids, task ids and subsystems

[Ludovic Courtès]

Hi,

On Thu, Apr 03, 2003 at 12:39:48PM +0200, Niels Möller wrote:
> I think one would want to associate all the tasks in the subhurd with
> a single process/task in the parent, perhaps the boot process. One way
> to do that may be to use a proxy task server.

Assuming that proc is the server that assigns PIDs upon task creation,
the Hurd semantics currently allow to create a hierarchical PID
management: You can run a task with your own proc server (just like
"fakeauth" allows to run a task with your own auth server and just like
"settrans --chroot" allows to run a task with an arbitrary / server)
which can be a proxy of its proc server.  I think PID management is
inherently hierarchical since a task inherits its proc handle from its
parent task.

This way, it is possible to create hierarchies of proc (or auth or /)
servers.  The first proc server ("root proc server") could talk directly
to the entity that actually creates tasks (either Mach or the task/root
server on L4).  If other proc servers are launched, they would just talk
to their own proc server (the parent proc server).  Then there exists a
mapping between PIDs assigned by a proc server and the PIDs assigned by
its parent proc server.  The root proc server would maintain a mapping
between PIDs and the corresponding task ids (they could just be the
same).

I'm not familiar with subhurds so maybe I'm just restating what already
exists. ;)  However, according to [1], subhurd tasks seems to appear as
"unknown processes" in the parent Hurd (but they *do* appear).

Thanks,
Ludovic.

[1] http://www.nongnu.org/thug/subhurd.html