[coyotos-dev] Sleep for interval

[Marcus Brinkmann]

At Sun, 30 Sep 2007 19:38:31 -0400,
"Jonathan S. Shapiro" <shap at eros-os.com> wrote:
> 
> On Sun, 2007-09-30 at 22:17 +0200, Marcus Brinkmann wrote:
> > PS: More interesting (and much more difficult a problem) than
> > emulating all kernel objects is the emulation of selected kernel
> > objects.
> 
> Just FYI, when Charlie and I talk about emulating kernel objects, we
> generally mean "one at a time". That is, we are talking about
> virtualizing a single capability or set of related capabilities, not the
> entire kernel API.

As far as scheduling is concerned, running the server with a higher
priority still achieves the desired effect.  But there may be other
side-effects of emulation, of course.  For example, how do you emulate
a page that becomes part of an address space?  The kernel does not
forward the read_cacheline and write_cacheline RPCs that are required
in the model (but actually implemented by the hardware without kernel
involvement) to the server.

Anyway, even though in the general case it seems difficult, for the
specific case of the Sleep interface I believe per-object emulation
can be feasible, if the interface is chosen carefully.  In fact, it
could be a good argument in favor of the Sleep interface and against
timeout parameters in the IPC system call (assuming relevant use cases
can be found which require such emulation).

Thanks,
Marcus