oprofile and ARM A9 hardware counter

[Will Deacon]

Mans,

On Fri, Jan 27, 2012 at 12:56:35PM +0000, Måns Rullgård wrote:
> Will Deacon <will.deacon at arm.com> writes:
> > Did this lead anywhere in the end? It seems as though Ming Lei has a working
> > setup but Stephane is unable to replicate it, despite applying the necessary
> > patches and trying an updated bootloader.
> 
> With the patches listed above plus the one in [1], I get PMU interrupts.
> However, unless I restrict the profiled process to one CPU
> (taskset 1 perf record ...), I get a panic in armpmu_event_update() with
> the 'event' argument being null when called from armv7pmu_handle_irq().
> 
> [1] http://article.gmane.org/gmane.linux.ports.arm.omap/69696

Great, thanks for trying this out. Which version of the kernel were you
using? I fixed a bunch of NULL pointer derefs. during the 3.2 window, but if
you were using an -rc kernel you have have hit one of them.

Will