From: Toshi Kani <toshi.kani@hpe.com>
To: Paul Gortmaker <paul.gortmaker@windriver.com>,
Borislav Petkov <bp@suse.de>
Cc: 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: Thu, 10 Mar 2016 13:12:02 -0700 [thread overview]
Message-ID: <1457640722.15454.557.camel@hpe.com> (raw)
In-Reply-To: <20160310190429.GI23251@windriver.com>
On Thu, 2016-03-10 at 14:04 -0500, Paul Gortmaker wrote:
> [Re: runtime regression with "x86/mm/pat: Emulate PAT when it is
> disabled"] On 10/03/2016 (Thu 18:20) Borislav Petkov wrote:
>
> > On Thu, Mar 10, 2016 at 09:49:51AM -0700, Toshi Kani wrote:
> > > This confirms the issue - QEMU's virtual Intel CPU does not support
> > > MTRR.
> > >
> > > When MTRR is disabled, the kernel does not call pat_init().
> > > pat_enabled() is still set to true when CONFIG_X86_PAT is set.
> > > CONFIG_X86_PAT depends on CONFIG_MTRR, and assumes that MTRR is
> > > enabled.
> >
> > Aha, so "qemu32" model doesn't support MTRRs but "kvm32" does, for
> > example. And so do the majority of the other CPU types.
>
> So, I guess that is a qemu bug? If there is no real silicon out there
> that has no MTRR but does claim PAT, then qemu32 is a flawed CPU type?
It turns out that your qemu's virtual CPU does not support PAT, either. :-)
So, it is consistent on this regard. I will send patches to address this
issue.
Thanks,
-Toshi
next prev parent reply other threads:[~2016-03-10 19:19 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1457640722.15454.557.camel@hpe.com \
--to=toshi.kani@hpe.com \
--cc=bp@suse.de \
--cc=bruce.ashfield@windriver.com \
--cc=darren.hart@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paul.gortmaker@windriver.com \
--cc=richard.purdie@linuxfoundation.org \
--cc=saul.wold@intel.com \
--cc=toshi.kani@hp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).