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Date: Wed, 20 Apr 2011 17:46:58 +0200
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Borislav Petkov <bp@amd64.org>
Cc: rwhitton@iee.org, Clemens Ladisch <clemens@ladisch.de>,
        linux-kernel@vger.kernel.org
Subject: Re: Background memory scrubbing
Message-ID: <20110420154658.GD1624@x4.trippels.de>
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 <4DAEF98D.2090802@ladisch.de>
 <20110420153529.GA2312@gere.osrc.amd.com>
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On 2011.04.20 at 17:35 +0200, Borislav Petkov wrote:
> On Wed, Apr 20, 2011 at 05:19:41PM +0200, Clemens Ladisch wrote:
> > > Unfortunately in common with a large number of hardware platforms
> > > background scrubbing isn't supported in the hardware (even though ECC
> > > error correction is supported) and thus there is no BIOS option to
> > > enable it.
> > 
> > Which hardware platform is this?  AFAICT all architectures with ECC
> > (old AMD64, Family 0Fh, Family 10h) also have scrubbing support.
> > If your BIOS is too dumb, just try enabling it directly (bits 0-4 of
> > PCI configuration register 0x58 in function 3 of the CPU's northbridge
> > device, see the BIOS and Kernel's Developer's Guide for details).
> 
> Or even better, if on AMD, you can build the amd64_edac module
> (CONFIG_EDAC_AMD64) and do
> 
> echo <x> > /sys/devices/system/edac/mc/mc<y>/sdram_scrub_rate
> 
> where x is the scrubbing bandwidth in bytes/sec and y is the memory
> controller on the machine, i.e. node.

BTW is it really necessary to print the following to syslog:

EDAC amd64: pci-read, sdram scrub control value: 15
EDAC MC: Read scrub rate: 97650

everytime one runs:
 # cat /sys/devices/system/edac/mc/mc0/sdram_scrub_rate
97650

?
-- 
Markus
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