RE: [BUG]: Intel uncore boot warning introduced in 4.1

From: Liang, Kan
Date: Mon Aug 10 2015 - 09:23:55 EST

> On Thu, Aug 06, 2015 at 06:10:40PM +0000, Liang, Kan wrote:
> > The issue may be caused by uncore box initialization.
> >
> > For preventing the potential issues of uncore box initialization, I
> > once moved the uncore_box_init() out of driver initialization in
> > commit c05199e5a57a579fea1e8fa65e2b511ceb524ffc.
> >
> > However, it cause some desktop crash, because the box initialization
> > codes were moved in IPI context.
> >
> > For fixing the crash issue, we had two choice at that time.
> > - Simply revert the codes. That's where is
> > 15c1247953e8a45232ed5a5540f291d2d0a77665 from.
> > - Move uncore_box_init out of IPI context to uncore event
> > init. I provided a patch for it.
> > Stephane Eranian also verified it on his platform
> >
> > At that time, we chose first option. But it looks there is some issue
> > now. I guess we may try the second option this time.
> >
> > Matthew,
> >
> > Could you please revert
> > 15c1247953e8a45232ed5a5540f291d2d0a77665
> > and apply the patch
> > See if it works?
> That patch is wrong though; how can even publish a PMU which is not
> initialized?

It's initialized but not in the driver initialization.
We once encountered boot crashes which caused by uncore
driver who trying to access non-existing boxes. Also this uncore
boot warning.
So I think it's better to move the box init code out of driver
initialization to prevent such potential boot failures.
Uncore event init should be a good place to do box init.
Only when the box is not initialized and user tries to use
uncore event, we do box initialization.

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