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Message-ID: <18563.1303314382@jupiter.eclipse.co.uk>
To: "Borislav Petkov" <bp@amd64.org>, <rwhitton@iee.org>
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Date: Wed, 20 Apr 2011 16:46:22 +0100
Subject: Re: Background memory scrubbing
From: Robert Whitton <rwhitton@iee.org>
Cc: "Clemens Ladisch" <clemens@ladisch.de>, <linux-kernel@vger.kernel.org>
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> 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  > /sys/devices/system/edac/mc/mc/sdram_scrub_rate
> 
> where x is the scrubbing bandwidth in bytes/sec and y is the memory
> controller on the machine, i.e. node.
> 
> -- 
> Regards/Gruss,
> Boris.
> 

Unfortunately that also isn't an option on my platform(s). There surely must be a way for a module to be able to get a mapping for each physical page of memory in the system and to be able to use that mapping to do atomic read/writes to scrub the memory.
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