[okl4-developer] Capability Passing in OKL4 3.0

[Gernot Heiser]

Hi Toby,

> it wasn't clear whether capabilities can be passed during IPC. Can
> they? If not, how can capabilities be passed between different
> address spaces?

As you'll have noticed, the OKL4 API is very much in flux. 2.1 was the
first release that introduced caps, but it should be clear that this
is only a first step. 3.0 took it a bit further, but there is still a
fair bit to go.

The present OKL4 system is aimed to support the current market
requirements of the type of embedded-systems customers we are dealing
with. These are generally systems with static configurations of
protection domains. As such, the support for dynamic PDs is limited in
the present kernel.

Specifically, while the kernel does support adding caps to clists, it
doesn't presently provide a way to transfer them by IPC. Hence only
a "privileged" thread that has access to both parties' Clists can
transfer a cap between them.

Stay tuned for increased functionality in forthcoming releases.

Gernot