[ltt-dev] OMAP3/4 trace clock and lockdep tracing

[Harald Gustafsson]

Hi,

I'm currently porting the higher precision OMAP3/4 trace clock aka
non-generic to another dual-core ARMv7 architecture. The port is not
fully debugged yet but I discovered one strange thing that I wonder if
anyone have experienced on the OMAP3/4 as well. If I use the
non-generic trace clock and have lockdep tracing turned on the system
freezes (no output) but the soft lockup cleaner kills of a process
each 61 seconds and dumps its output. Without the non-generic clock I
don't have this problem and without the lockdep tracing I don't have
this problem even when using the non-generic clock. To clarify it is
the lockdep tracing that show the problem, if I only have lockdep
configured it is no problem.

Have anyone run lockdep tracing on the OMAP3/4 using the non-generic
trace clock (i.e. normal LTTng config) and had this problem? This
would help me understand if it is only a porting issue or if there is
some deeper bug to find.

I use a 2.6.34 kernel (with LOCKDEP, LOCKDEP_DEBUG, DEBUG_LOCK_ALLOC,
PROVE_LOCKING, DEBUG_SPINLOCK, LOCK_STAT, and DEBUG_TRACE_CLOCK on)
with lttng 0.221 currently for compatibility with other SW and HW.

Regards,
 Harald Gustafsson