Re: [Xenomai-help] page faults

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

Jeff Weber wrote:
 > On Monday 16 April 2007 16:34, Gilles Chanteperdrix wrote:
 > > Jeff Weber wrote:
 > >  > On Monday 16 April 2007 15:43, Gilles Chanteperdrix wrote:
 > >  > > If the fault you observe is due to an access to some memory after a
 > >  > > call to fork or one of its derivative (such as system, popen, etc...),
 > >  > > the patch would have copied the whole real-time process address space
 > >  > > at fork time instead of setting up COW mappings.
 > >  >
 > >  > No process forks are involved.  Though mlockall() was called from Linux
 > >  > main(), and the page fault was encountered by a separate Xenomai task.
 > >  > Here's the task history:
 > >
 > > The fork may well be hidden in some library. The best way to know if
 > > there is really no fork is to register a callback with pthread_atfork.
 > pthread_atfork confirms that there is no fork.

Ok. I am afraid you will have to help us a bit. Could you try Xenomai
2.3.1 in case the nocow patch magically solves your issue ?

If it does not, could you try sizing down your program to a small
example that we could run to reproduce the issue ?

If reducing your program is not possible, the only option left is to
start debugging this issue. A good starting point would be to put some
printks in arch/i386/mm/fault.c to see what kind of page fault is
causing the mode switch.

-- 


					    Gilles Chanteperdrix.