oprofile and ARM A9 hardware counter

[Måns Rullgård]

Will Deacon <will.deacon at arm.com> writes:

> 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.

This was with the Linaro tilt-3.2 kernel from
git://git.linaro.org/landing-teams/working/ti/kernel.git, commit
73e2c294444f209d281f7cd10b52b53b087e74f1.  Maybe one of the many patches
it has on top of 3.2 is to blame.

-- 
Måns Rullgård
mans at mansr.com