Re: [linuxtools-dev] Oprofile plugin issues with Power processors

[Severin Gehwolf <sgehwolf@xxxxxxxxxx>]

On Fri, 2011-02-25 at 15:49 -0300, Daniel HB wrote:
> I'm currently trying to make the Oprofile plugin work on a Power6
> machine. I've come to this mailing list a couple weeks ago with a
> complaint that generated a bug
> ( https://bugs.eclipse.org/bugs/show_bug.cgi?id=336977 ) which we
> managed to solve - the XML error was a bogus character generated on the
> oprofile application for Power.
> 
> That wasn't enough to make the plugin work. On some point of its
> initialization, the plugin queries 'ophelp <event_name>' searching for
> index values to each event detected. It turns out that, on x86, these
> events are valid integer values, and the plugin was built around that
> assumption. However, on Power, they aren't always a valid integer.
> Several 'ophelp <event_name>' calls on Power returns several hex values,
> firing an exception on the plugin since an integer value was expected.
> 
> Speaking with Maynard Johnson, lead maintainer of Oprofile, we agreed
> that the plugin shouldn't be using any value obtained by 'ophelp
> <event_name>' since it's a non-architected interface. In other words,
> the GUI shouldn't be issuing this command neither using its return
> value.

I see. The obvious follow-up question is what does Maynard suggest to
use instead?

> Since it's quite a change on the code (I took a look at where the output
> of ophelp is used and there are a lot of places), I think I would need
> some help doing that.

Ok, I'd be happy to work with you on that. We should aim for a solution
which will work on x86 and Power (both 32 and 64 bit, at least). Ideally
there is some architected interface we could use.

> Any thoughts/advice?

Could you please open an Eclipse.org bug so that we can hash out details
there? Please CC me to that bug you open (sgehwolf@xxxxxxxxxx) and we
continue our discussion there.

Thanks!

--Severin

> - daniel
> 
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