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From: Toshi Kani <toshi.kani@hpe.com>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Borislav Petkov <bp@suse.de>,
	Richard Purdie <richard.purdie@linuxfoundation.org>,
	Toshi Kani <toshi.kani@hp.com>,
	Bruce Ashfield <bruce.ashfield@windriver.com>,
	"Hart, Darren" <darren.hart@intel.com>,
	"saul.wold" <saul.wold@intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"
Date: Mon, 07 Mar 2016 17:56:18 -0700	[thread overview]
Message-ID: <1457398578.15454.421.camel@hpe.com> (raw)
In-Reply-To: <20160307235328.GD26051@windriver.com>

On Mon, 2016-03-07 at 18:53 -0500, Paul Gortmaker wrote:
> [Re: runtime regression with "x86/mm/pat: Emulate PAT when it is
> disabled"] On 07/03/2016 (Mon 16:38) Toshi Kani wrote:
> 
> > On Mon, 2016-03-07 at 16:08 -0500, Paul Gortmaker wrote:
> > > [dropping oe list and lkml since attaching dmesg files.]
> > > 
> 
> [...]
> 
> > > > Yes, please send me full dmesg files.  Since I do not know your
> > > > original state, the diff does not give me the whole picture.
> > > 
> > > Attached.
> > 
> > Thanks for the dmesg files!  As I suspected, there is no message from
> > pat_init() in both cases.  That is, you are missing the following
> > message,
> > which shows how PAT is configured to support cache attributes.
> > 
> > # dmesg | grep PAT
> > [0.000000] x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC-
> > WT  
> 
> Interesting...
> 
> > 
> > It may have seemed working before, but you did not have WC configured
> > to PAT without calling pat_init().  There was not a proper check in
> > place to detect this error before.  Can you please check your code to
> > see what caused this skip of pat_init()?  If you have a git tree, I can
> > take a look as well. 
> 
> You already have git copies of what I'm running, since it is vanilla
> mainline commits.  No code changes at this end whatsoever.  I did the
> bisect on vanilla mainline.  All I took from yocto was their ".config"
> 
> To recap, v4.1-rc5-21-g9dac62909451 works,  v4.1-rc5-22-g9cd25aac1f44
> fails, and v4.5-rc6 also fails.  If pat_init() isn't called then this
> is a bug in current mainline.  I'll have a look later myself and see
> if I can trace out how we expect to get to pat_init() and how that
> might be skipped inadvertently unless someone beats me to it.

Oh, I see.  Can you send me the ".config" file?

Thanks,
-Toshi

  reply	other threads:[~2016-03-08  0:03 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-03 20:59 runtime regression with "x86/mm/pat: Emulate PAT when it is disabled" Paul Gortmaker
2016-03-03 21:18 ` Paul Gortmaker
2016-03-04  5:02 ` Toshi Kani
2016-03-04 18:37   ` Paul Gortmaker
2016-03-04 22:12     ` Toshi Kani
2016-03-07  0:35       ` Paul Gortmaker
2016-03-07 16:03         ` Toshi Kani
     [not found]           ` <20160307210852.GC26051@windriver.com>
2016-03-07 23:38             ` Toshi Kani
2016-03-07 23:53               ` Paul Gortmaker
2016-03-08  0:56                 ` Toshi Kani [this message]
2016-03-08  1:35                   ` Toshi Kani
2016-03-08  3:28                     ` Paul Gortmaker
2016-03-08 16:38                       ` Toshi Kani
2016-03-10 14:42                     ` Paul Gortmaker
2016-03-10 16:49                       ` Toshi Kani
2016-03-10 17:20                         ` Borislav Petkov
2016-03-10 19:04                           ` Paul Gortmaker
2016-03-10 19:19                             ` Borislav Petkov
2016-03-11 13:23                               ` One Thousand Gnomes
2016-03-11 13:40                                 ` Borislav Petkov
2016-03-11 19:18                                   ` Paolo Bonzini
2016-03-11 22:16                                     ` Borislav Petkov
2016-03-11 22:28                                       ` Bruce Ashfield
2016-03-11 23:29                                         ` Richard Purdie
2016-03-12 12:03                                           ` Borislav Petkov
2016-03-10 20:12                             ` Toshi Kani
2016-03-10 20:04                           ` Toshi Kani
2016-03-10 19:20                             ` Borislav Petkov
2016-03-10 20:24                               ` Toshi Kani
2016-03-10 21:07                                 ` Borislav Petkov
2016-03-10 23:17                                   ` Toshi Kani
2016-03-08  3:16                   ` Paul Gortmaker
2016-03-08 16:13                     ` Toshi Kani
2016-03-08 16:03                       ` Paul Gortmaker
2016-03-08 17:01                         ` Toshi Kani

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