Re: [Xenomai] BUG: Unhandled exception over domain Xenomai - switching to ROOT

["Jorge Ramirez Ortiz, HCL Europe" <Jorge.Ramirez-Ortiz@hcl.com>]

Thanks. I appreciate the time you took to to remind me (again) of this interface and the issues when notifying linux from the realtime domain. 
I also should have read the doxygen docs more carefully (!)
cheers
jorge



-----Mensaje original-----
De: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org] 
Enviado el: 13 July 2012 18:48
Para: Jorge Ramirez Ortiz, HCL Europe
CC: Jan Kiszka; xenomai@xenomai.org
Asunto: Re: [Xenomai] BUG: Unhandled exception over domain Xenomai - switching to ROOT

On 07/13/2012 06:27 PM, Jorge Ramirez Ortiz, HCL Europe wrote:
> Please can we go back and reframe the discussion?
> 
> But first I'll reiterate: do ignore the marginal issue I had with the
> framework (I ported and went over 44,785 lines of ANSI-C(kernel/user)
> and 1995 lines of C++ code  in just a few days -this one was a big
> pci driver-....I am not really losing my sleep over it) . Besides It
> is not really relevant to the point I am trying to make and the
> reason why I am posting here.
> 
> My point is: yes, absolutely, I would expect the framework to allow
> wakeup calls to linux services from interrupt context. Why not? Why
> is this the wrong expectation to have?

Because waking up a task means interacting with Linux scheduler, which,
in turn, means interacting with the scheduler data structures. But the
reason why xenomai has low latencies is because its interrupts may
interrupt linux anywhere, including in the middle of a critical section
where the scheduler data structures are in an inconsistent state. So,
you see, it can not work.


> And anyhow, failing that, I would have expected the real-time driver
> model to give the user the option to chose the back door context he
> wants to register to (which is my whole point and what  PREEMPT_RT
> actually does in the linux domain). And I would expect an rtdm
> interface for that.

rtdm has an interface for that, it is called rtdm_nrtsig.

-- 
					    Gilles.


::DISCLAIMER::
----------------------------------------------------------------------------------------------------------------------------------------------------

The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only.
E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted,
lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents
(with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates.
Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the
views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification,
distribution and / or publication of this message without the prior written consent of authorized representative of
HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately.
Before opening any email and/or attachments, please check them for viruses and other defects.

----------------------------------------------------------------------------------------------------------------------------------------------------