L4Linux threads - interrupt context

Oskar Senft o.senft at sirrix.com
Fri Aug 25 12:17:24 CEST 2006

Hi Björn!

> Why do you need Linux functions to do L4 IPC?
We need them, because we want to provide (L4)Linux kernel features to other
L4/L4Linux tasks.

> Sleeping in IPC in an IRQ context works. Have a look at
drivers/net/l4ore.c - this is a
> network driver interfacing the ORe network server. It runs in IRQ context
and does
> blocking IPC to an external server.
Yes, but that's the other way round - that's already working. I was talking
about the IPC-*Server* side where you might run into a *Linux* function
that wants to go into *Linux* sleep which normally causes scheduling within

> This is a known limitation of the L4v2 API and there are many packages in
the L4 tree that
> handle these situations, for instance l4/pkg/l4vfs/term_server, and
Yes, I know that. I also described a way how it can be handled. What I was
asking for, was *another* way, a simpler way of solving this problem.

AFAIR there is a discussion (or even more) about "separated" IPC where some
arbitrary thread of a task may reply to an incoming IPC to another thread
of that task.


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