Messages in this thread | | | Date | Tue, 12 Jun 2012 17:13:08 +0200 | From | Stefan Bader <> | Subject | Re: CPU MTRRs and linux kernel |
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On 12.06.2012 15:48, Mahmood Naderan wrote: > Thanks Borislav, > I want to know, should I upgrade to the latest kernel or it is possible to download the source of 2.6.32-24 from repository and modify cleanup.c and then recompile? > Just update to the latest kernel. 2.6.32-24.39 is way old. The fix Boris mentioned was in 2.6.32-27.49. And the latest kernel is 2.6.32-41.89 by now...
-Stefan
> ~MN > > ----- Original Message ----- > From: Borislav Petkov <bp@alien8.de> > To: Mahmood Naderan <nt_mahmood@yahoo.com> > Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>; Andreas Herrmann <andreas.herrmann3@amd.com> > Sent: Tuesday, June 12, 2012 3:09 PM > Subject: Re: CPU MTRRs and linux kernel > > 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 <andreas.herrmann3@amd.com> > 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 <andreas.herrmann3@amd.com> > LKML-Reference: <20100930123235.GB20545@loge.amd.com> > Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> > > 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) >
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