> Date: Wed, 11 Jan 2012 20:03:25 +0100
> From: gilles.chanteperd...@xenomai.org
> To: jan0...@hotmail.de
> CC: xenomai-core@gna.org
> Subject: Re: [Xenomai-core] Question about context switching
> 
> On 01/11/2012 07:12 PM, Jan-Erik Lange wrote:
> > 
> > Hello,
> > 
> > I have a question about the context switching:
> > 
> > Unless that there a rtdm_copy_to_user() available in the rtdm API.
> > Would cause the function copy_to_user() in an xenomai kernel based rt
> > task a switch into the secondary domain? Because copy_to_user() not
> > actually a syscall right?
> 
> Absolutely no function in kernel-space causes an automatic switch to
> secondary mode. As Philippe answered to the very first mail you posted
> to this list, the only events which cause a switch to secondary mode are:
> 
> - invoking a regular linux syscall
> - receiving a linux signal (e.g. kill(2) and GDB)
> - causing a CPU trap (e.g. invalid memory access), hitting a breakpoint
> (e.g. GDB)
> 
> All these events only happen for threads in user-space.

Sorry I'm new in Xenomai.

But is it generaly possible that the xenomai kernel-space task can interact 
with a common Linux task over this way? I mean is it possible to get data with 
the standard copy_to_user()-function from the Xenomai kernel-space into the 
Linux user space? Aren't the adress spaces strictly seperated and you have to 
need the rt-pipe service to interact between the xenomai kernel space and the 
linux userspace?

> 
> -- 
> Gilles.
                                          
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