Re: Preempt-RT on OMAP3?

David Brownell
2009-04-07T02:27:13Z

> > RX DMA is troublesome with the MUSB code, and there are some bugfixes
> > pending which should affect it.  (Posted to linux-usb over the last
> > week or two.)
> >
> > Do these problems show up with DMA disabled?
>
> I guess you mean with CONFIG_MUSB_PIO_ONLY - yes, I've tried that. I
> don't observe the Rx DMA problems as described previously in that
> configuration, no ........

Good...

> However I instead I see hard-lockups with
> no obvious cause and no messages printed to the console. (The only
> repeatable one I've found so far is exiting cyclictest with ^C. Not
> good). These lockups could well be and probably are unrelated, but
> none-the-less, it's very troubling!

Given the bootlog excerpt you posted, I'm thinking there are
still some basic goofy things with the RT patches you're using
even outside the scope of MUSB. Basic as in timer tick and
kernel thread setup; lots of things look goofy.

> I've uploaded my defconfig here:
> http://hugovincent.com/files/lkml-20090407/
> along with a log of the bootup process. I've enabled a bunch of debug
> options and self-tests. You can see the rather verbose output of some
> spinlock tests (I think) failing early in the bootup process,
> somewhere in timer initialization (I think?).

Those look like lockdep things. Get a more complete boot log
and maybe someone will be able to sort out what's up.

- Dave

>
> Regards,
> Hugo