[Xenomai] [XENOMAI] TIP_HEAD bit during Xenomai initialisation

Julien Stephan julien.stephan at smile.fr
Thu Dec 8 11:33:42 CET 2016


Hello,

We are trying to port xenomai to a new architecture.
So far, we have ported the ipipe patch, the xenomai kernel and the
xenomai librairies, though we are not 100% sure everything is working
properly.

We are porting xenomai 3 ( Cobalt v3.0.3 (Groovy Cosmic Halo)  ) with a
linux kernel 3.18. For now, we are able to boot linux correctly, with
xenomai correctly registered:
~ # dmesg | grep -i xenomai
[Xenomai] scheduling class idle registered.
[Xenomai] scheduling class rt registered.
I-pipe: head domain Xenomai registered.
[Xenomai] Cobalt v3.0.3 (Groovy Cosmic Halo)

So far so good.

Now, I tried to run a very basic hello world program that has no
real-time properties. We compile it using the example makefile given
here (https://xenomai.org/building-applications-with-xenomai-3-x/) so
that even if the application is not a real time application, the Xenomai
services are initialized.

At run time, we get the following error:
0"000.000| BUG in low_init(): [main] Cobalt core not enabled in kernel

This bug appears in the low_init function in lib/cobalt/init.c after the
XENOMAI_SYSBIND call.
By stepping into the syscall handler with gdb, I noticed that TIP_HEAD
bit of thread_info was not set and then we just go to the slow_path,
then root_syscall  path  (see ARM ipipe patch for assembly labels)  and
finally end up into the traditional linux handler that return -ENOSYS as
the syscall number of XENOMAI_SYSBIND is greater than the linux kernel
syscall limit.

So my question is: during initialization of the xenomai services, the
TIP_HEAD bit should be set or not?


Thanks for your help.
Julien
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