From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753646AbZEYImU (ORCPT ); Mon, 25 May 2009 04:42:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751781AbZEYImF (ORCPT ); Mon, 25 May 2009 04:42:05 -0400 Received: from mx03.syneticon.net ([78.111.66.105]:44780 "EHLO mx03.syneticon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751550AbZEYImE (ORCPT ); Mon, 25 May 2009 04:42:04 -0400 Message-ID: <4A1A59DD.7030101@wpkg.org> Date: Mon, 25 May 2009 10:42:05 +0200 From: Tomasz Chmielewski User-Agent: Thunderbird 2.0.0.21 (X11/20090319) MIME-Version: 1.0 To: LKML CC: mingo@elte.hu, Alan , Gerd Hoffmann , jeremy@goop.org, Andi Kleen , "H. Peter Anvin" , JBeulich@novell.com, jbarnes@virtuousgeek.org Subject: Re: [Xen-devel] Re: [GIT PULL] xen /proc/mtrr implementation Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: >>>> Oops, the third "proper technical solutions" is missing. >>> >>> Yeah, the third one is to not touch MTRRs after bootup and use PAT. >> >> Works only in case the CPU has PAT support. > > Which specific CPU without PAT support do you worry about? Are these ones (below) good CPU to worry about? That's slightly off-topic as they are KVM guests, but still, the guest kernel seems to disable PAT (unless I'm mistaken). KVM-86 + 2.6.27.19 guest: # dmesg Initializing cgroup subsys cpuset Linux version 2.6.27.19-server-1mnb (qateam@titan.mandriva.com) (gcc version 4.3.2 (GCC) ) #1 SMP Thu Mar 5 00:09:04 EST 2009 PAT WC disabled due to known CPU erratum. (...) # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 2 model name : QEMU Virtual CPU version 0.10.50 stepping : 3 cpu MHz : 2133.285 cache size : 2048 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall lm up pni bogomips : 4266.57 clflush size : 64 power management: KVM-85 + 2.6.29.1 guest: # dmesg Initializing cgroup subsys cpuset Initializing cgroup subsys cpu Linux version 2.6.29.1-server-4mnb (herton@n2.mandriva.com) (gcc version 4.3.2 (GCC) ) #1 SMP Mon Apr 20 20:10:24 EDT 2009 KERNEL supported cpus: Intel GenuineIntel AMD AuthenticAMD NSC Geode by NSC Cyrix CyrixInstead Centaur CentaurHauls Transmeta GenuineTMx86 Transmeta TransmetaCPU UMC UMC UMC UMC PAT WC disabled due to known CPU erratum. (...) # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 2 model name : QEMU Virtual CPU version 0.10.0 stepping : 3 cpu MHz : 2128.004 cache size : 2048 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx lm up pni hypervisor bogomips : 4256.00 clflush size : 64 power management: -- Tomasz Chmielewski http://wpkg.org