Unset LOCKDEP and TRACE_IRQFLAGS_SUPPORT

[vibnwis]

It is a surprise for getting a reply from you, Gilles on this subject which
I had posed on Xenomai forum and has been treated as if it was coming from
an  "idiot".

Knowing this is not entirely Xenomai forum, I would still like to ask if I
can get hold of the patch, please? if not, hear from you in Xenomai forum.

On 3 October 2015 at 05:11, Gilles Chanteperdrix <
gilles.chanteperdrix at xenomai.org> wrote:

> On Fri, Oct 02, 2015 at 09:56:39AM -0600, Jim Cromie wrote:
> > On Sun, Sep 27, 2015 at 8:52 AM, <Valdis.Kletnieks at vt.edu> wrote:
> >
> > > On Sun, 27 Sep 2015 15:08:57 +1300, vibnwis said:
> > >
> > > > Xenomai patching succeeded but when running one of is test apps,
> > > "latency"
> > > > showing
> > > > > > > > > > >> > 0"000.000| BUG in low_init(): [main] mlockall:
> Cannot
> > > > allocate
> > > > > > > > memory
> > > > And the mailing list member suggested the following
> > >
> > > Is that in dmesg, or output from the test program?
> > > Is there more output, or is that it?
> > >
> > > Personally, if TRACE_IRQFLAGS is causing an issue with mlock, I'd
> suspect
> > > a very buggy patch indeed.  If it can't tolerate a trace function being
> > > turned on, there;s probably some very questionable coding in there.....
> > >
> > >
> >
> > FWIW, I think Xenomai is far better smelling than your quick sniff has
> told
> > your olfactory sensors
>
> TRACE_IRQFLAGS is broken with the I-pipe patch. At least on ARM. The
> visible result is LOCKDEP false positives, but there may be some
> more subtle kernel data structures corruption due to the fact that
> the TRACE_IRQFLAFGS code is called from the Xenomai context. The
> principle of Xenomai is to be able to run while Linux believes
> its interrupts are off, in the middle of its critical sections. For
> this to be possible, the code run in this context must never touch
> any Linux kernel data structures. Enabling TRACE_IRQFLAGS breaks
> this assumption: Linux code which potentially accesses Linux data
> structures gets called from the Xenomai context. The consequences
> can be anything, such as mlock failing, though in practice we never
> get any report about that. The usual reason for mlockall failing is
> because the user is not root, and with default ulimit settings at
> least, mlockall can not be called by non-root users.
>
> Anyway, the reason why TRACE_IRQFLAGS is still broken is my fault:
> Jan has sent patches months ago, which I did not check.
>
> --
>                                             Gilles.
> https://click-hack.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20151004/005c6f6d/attachment-0001.html