oprofile and ARM A9 hardware counter

[Måns Rullgård]

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

> Hi guys,
>
> On Sat, Jan 21, 2012 at 09:16:57AM +0000, stephane eranian wrote:
>> On Sat, Jan 21, 2012 at 4:25 AM, Ming Lei <ming.lei at canonical.com> wrote:
>> > On Fri, Jan 20, 2012 at 9:47 PM, stephane eranian
>> > <eranian at googlemail.com> wrote:
>> >> Started afresh from:
>> >>
>> >> 90a4c0f uml: fix compile for x86-64
>> >>
>> >> And added 3, 4, 5, 6:
>> >> 603c316 arm: omap4: pmu: support runtime pm
>> >> 4899fbd arm: omap4: support pmu
>> >> d737bb1 arm: omap4: create pmu device via hwmod
>> >> 4e0259e arm: omap4: hwmod: introduce emu hwmod
>> >>
>> >> Still no interrupts firing. I am using your .config file.
>> >>
>> >> My HW:
>> >> CPU implementer : 0x41
>> >> CPU architecture: 7
>> >> CPU variant     : 0x1
>> >> CPU part        : 0xc09
>> >> CPU revision    : 2
>> >>
>> >> Hardware        : OMAP4 Panda board
>> >> Revision        : 0020
>> >>
>> >> There must be something I am missing here.
>
> 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

-- 
Måns Rullgård
mans at mansr.com