Re: [Xenomai-help] Question about getting system time

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Steve Deiters wrote:
> Even more of a problem is how I am supposed to know which calls are
> similar to this.  I would expect I could call any Linux service without
> causing a deadlock/livelock situation, although in a nondeterministic
> manner.  If I understood your explanation correctly, this is hanging
> whenever the Xenomai task tries to spin on the same lock as the kernel.
> However, I don't see how this is not a problem in general for acquiring
> any spinlock from a Xenomai task.  I would expect once you introduce a
> priority based scheduler any spinlock becomes unsafe.

The set of services which you can call from a real-time thread without
loosing determinism are those found in the Xenomai posix skin documentation:
http://www.xenomai.org/documentation/xenomai-2.5/html/api/group__posix.html

Other than that, any service emitting a syscall causes a switch to
secondary mode. What remains are services not emitting syscalls, and for
these ones, all bets are off.

-- 
					    Gilles.