From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752031Ab2FLKj6 (ORCPT ); Tue, 12 Jun 2012 06:39:58 -0400 Received: from mail.skyhub.de ([78.46.96.112]:59868 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751505Ab2FLKj5 (ORCPT ); Tue, 12 Jun 2012 06:39:57 -0400 Date: Tue, 12 Jun 2012 12:39:54 +0200 From: Borislav Petkov To: Mahmood Naderan Cc: "linux-kernel@vger.kernel.org" , Andreas Herrmann Subject: Re: CPU MTRRs and linux kernel Message-ID: <20120612103954.GB10124@x1.osrc.amd.com> Mail-Followup-To: Borislav Petkov , Mahmood Naderan , "linux-kernel@vger.kernel.org" , Andreas Herrmann References: <1339493860.10145.YahooMailNeo@web111708.mail.gq1.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1339493860.10145.YahooMailNeo@web111708.mail.gq1.yahoo.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 12, 2012 at 02:37:40AM -0700, Mahmood Naderan wrote: > Hi everybody, > Abour rhis warnning in boot log: > > WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 61952MB of RAM > >   > I > searched a lot however didn't find a clear solution. Does AMD new > processors (62XX) have problems with new kernels or old kernels?? > Mine is: > > Linux n1 2.6.32-24-server #39-Ubuntu SMP Wed Jul 28 06:21:40 UTC 2010 x86_64 GNU/Linux > > Should I upgrade? Yes, fix is below and it got backported to -stable AFAICT but obviously the ubuntus don't have it in the kernel you cite above. commit 3fdbf004c1706480a7c7fac3c9d836fa6df20d7d Author: Andreas Herrmann Date: Thu Sep 30 14:32:35 2010 +0200 x86, mtrr: Assume SYS_CFG[Tom2ForceMemTypeWB] exists on all future AMD CPUs Instead of adapting the CPU family check in amd_special_default_mtrr() for each new CPU family assume that all new AMD CPUs support the necessary bits in SYS_CFG MSR. Tom2Enabled is architectural (defined in APM Vol.2). Tom2ForceMemTypeWB is defined in all BKDGs starting with K8 NPT. In pre K8-NPT BKDG this bit is reserved (read as zero). W/o this adaption Linux would unnecessarily complain about bad MTRR settings on every new AMD CPU family, e.g. [ 0.000000] WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 4863MB of RAM. Cc: stable@kernel.org # .32.x, .35.x Signed-off-by: Andreas Herrmann LKML-Reference: <20100930123235.GB20545@loge.amd.com> Signed-off-by: H. Peter Anvin diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c index c5f59d071425..ac140c7be396 100644 --- a/arch/x86/kernel/cpu/mtrr/cleanup.c +++ b/arch/x86/kernel/cpu/mtrr/cleanup.c @@ -827,7 +827,7 @@ int __init amd_special_default_mtrr(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) return 0; - if (boot_cpu_data.x86 < 0xf || boot_cpu_data.x86 > 0x11) + if (boot_cpu_data.x86 < 0xf) return 0; /* In case some hypervisor doesn't pass SYSCFG through: */ if (rdmsr_safe(MSR_K8_SYSCFG, &l, &h) < 0) -- Regards/Gruss, Boris.