[Xenomai] Issue while porting ipipe to kernel > 4.5 (clockevents API change)

Thierry Bultel thierry.bultel at basystemes.fr
Tue Apr 12 15:06:42 CEST 2016

Le 11/04/2016 17:05, Philippe Gerum a écrit :
> On 04/11/2016 11:45 AM, Thierry Bultel wrote:
>> Hi,
>> while porting ipipe to 4.5, I am facing the following issue:
>> clockchips.h has changed, and the set_mode function pointer has been
>> replaced by
>>      int            (*set_state_periodic)(struct clock_event_device *);
>>      int            (*set_state_oneshot)(struct clock_event_device *);
>>      int            (*set_state_oneshot_stopped)(struct
>> clock_event_device *);
>>      int            (*set_state_shutdown)(struct clock_event_device *);
>> Moreover, CLOCK_EVT_MODE_XXX have been renamed to :
>> enum clock_event_state {
>> };
>> The impact therefore goes further than ipipe , since xenomai uses a
>> single pointer
>> for performing emulation.
>> I am just wondering what is the best way to deal with this, without
>> impacting to much code
>> Is it best to add a compatibility wrapper (moreover, the set_state_xxx
>> functions are only used in clockevents.c), and some extra #defines
>> or to spread the changes up to xenomai code ?
> I would confine the changes to the pipeline, I don't see any reason for
> spreading those changes to Xenomai only for supporting the
> ONESHOT_STOPPED mode, which might be usable as a hint, but may be
> ignored by Xenomai as well, especially by legacy Xenomai 2.x releases.
> You could redirect the new state handlers to a set of internal wrapper
> routines in the pipeline, which would translate the calls to the
> Xenomai's current emulation handlers.

Thanks Philippe,

At this step, I have something that compiles without CONFIG_XENOMAI (there is a little work to do in xenomai,
since some other kernel APIs changed too, like cpu masks, and struct msghdr ... )

Before going to that, I would like to get rid of this:

The kernel boots fine with CONFIG_IPIPE disabled.

With CONFIG_IPIPE and !CONFIG_SMP, the kernel boots fine up to user land.
With CONFIG_IPIPE and  CONFIG_SMP, the kernel hangs at random positions during initcalls.
I had to enable CONFIG_EARLY_PRINTK to notice it, because nothing came on the console else.

"printk-bisecting" makes the hang position change, making impossible to localize the hang position this way.

I have CONFIG_DEBUG_SPINLOCK enabled but that does not help much. I payed much attention to spinlock.h without noticing
anything wrong.

What can I do to investigate this ?

I forgot to say that the target CPU is an IMX6Q


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