From: Paolo Bonzini <pbonzini@redhat.com>
To: Borislav Petkov <bp@suse.de>,
One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>,
Toshi Kani <toshi.kani@hpe.com>,
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, kvm ML <kvm@vger.kernel.org>,
x86-ml <x86@kernel.org>
Subject: Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"
Date: Fri, 11 Mar 2016 20:18:23 +0100 [thread overview]
Message-ID: <56E319FF.3090709@redhat.com> (raw)
In-Reply-To: <20160311134000.GC4347@pd.tnic>
On 11/03/2016 14:40, Borislav Petkov wrote:
> On Fri, Mar 11, 2016 at 01:23:56PM +0000, One Thousand Gnomes wrote:
>> > Pentium Pro has MTRR, PAT came later.
> Yep, this page says so too:
>
> http://www.cpu-world.com/CPUs/Pentium-II/Intel-Pentium%20Pro%20200%201%20MB%20-%20GJ80521EX200%201M%20%28BP80521200%201M%29.html
>
>> > I believe the qemu32 CPU isn't a "real" CPU type therefore.
> And why is that so? I suspect it has again something to do with
> migration and fun. Let me add the kvm ML.
>
> Guys, does anyone have an idea why
>
> #define PPRO_FEATURES (CPUID_FP87 | CPUID_DE | CPUID_PSE | CPUID_TSC | \
> CPUID_MSR | CPUID_MCE | CPUID_CX8 | CPUID_PGE | CPUID_CMOV | \
> CPUID_PAT | CPUID_FXSR | CPUID_MMX | CPUID_SSE | CPUID_SSE2 | \
> CPUID_PAE | CPUID_SEP | CPUID_APIC)
>
> has CPUID_PAT *instead* of CPUID_MTRR?
Somebody got it wrong 10-ish years ago, and nobody has ever checked since.
But, don't use qemu32 or qemu64. Use kvm32 and kvm64, or better
something like the host you run on ("-cpu Nehalem", "-cpu SandyBridge",
"-cpu Haswell-noTSX" etc.).
I really, really should fix those defaults...
Paolo
next prev parent reply other threads:[~2016-03-11 19:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1457393912.15454.419.camel@hpe.com>
[not found] ` <20160307235328.GD26051@windriver.com>
[not found] ` <1457398578.15454.421.camel@hpe.com>
[not found] ` <1457400913.15454.435.camel@hpe.com>
[not found] ` <20160310144250.GG23251@windriver.com>
[not found] ` <1457628591.15454.542.camel@hpe.com>
[not found] ` <20160310172029.GA2194@pd.tnic>
[not found] ` <20160310190429.GI23251@windriver.com>
[not found] ` <20160310191933.GC2194@pd.tnic>
[not found] ` <20160311132356.43a7b373@lxorguk.ukuu.org.uk>
2016-03-11 13:40 ` runtime regression with "x86/mm/pat: Emulate PAT when it is disabled" Borislav Petkov
2016-03-11 19:18 ` Paolo Bonzini [this message]
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
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