Re: physmem, simple containers

[Niels Möller]

Marcus Brinkmann <address@hidden> writes:

> In fact, wortel needs to tell the task server which task ids exist already
> for physmem etc.  More importantly, it needs to tell it about the thread
> ids already in use (and in the perspective of a manager OS, the thread ids
> it is allowed to use).

I think this can be fairly simple. Wortel must know about the usage of
the subsystem bits. I think we can also require that the threads
started by wortel get small and increasing numbers in the l4_version
field (this seems harmless, no matter if OS:es booted from wortel use
the version field the way we do, or the way intended by L4).

Then the task-server can simply examine it's own thread id to find out
what thread id:s it can and should use. The subsystem bits give the
subsystem value used for the hurd. The version bits gives the number
of reserved taskids (possibly plus/minus some hurd-specific constant
that need not really be known by wortel).

Any ipc from a thread with a subsystem different from the hurd
subsystem, or with version bits smaller than the reserved taskid, is
dropped on the floor by the task-server. More normal hurd servers need
not know about reserved taskid:s, they use only the subsystem bits and
local capability tables to make access control decisions.

Regards,
/Niels