Restarting siblings vs. restarting nieces

Christian Helmuth christian.helmuth at
Mon Feb 6 07:37:58 CET 2023


On Sun, Feb 05, 2023 at 13:42:06 CET, Martin Stein wrote:
> Let me share the outcome of our offline discussion with the mailing list:
> As far as I understand it, while Genode's init has the feature of
> restarting direct service clients when their session disappears, this
> doesn't apply in your scenario because of the server being wrapped in an
> additional sub-init.
> In such case, you have to manually take care for restarting your
> clients. A client, AFAIK deliberately doesn't consider the case that the
> outside world is terminating its session. So, it seems natural to me
> that you run into unpredictable behavior if you don't have some kind of
> manager that kills the client before terminating its session.

Thanks for this wrapup, Martin, it perfectly reflects my stance on the
matter too.

Regarding the followong question...

> Exception and try to re-establish the session. The two clients use
> the `vfs` plugin mechanism to access the `File_system` session
> provided by `rump`. During a restart of `rump` the clients sometimes
> page-fault and sometimes "live on" while responding to heartbeats
> but otherwise seem to be malfunctioning. Is the `vfs` plugin
> mechanism designed to handle these outages?

We refrained from implementing "probing" or "automatic retry" in many
places where the it is hard to nail down a sensible default policy. I
expect the VFS plugin misses your desired recover feature for this

Christian Helmuth
Genode Labs · ·

Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden
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