linux-kernel - Re: Linux* Processor Microcode Data File

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Message-ID: <20090309103042.GA20716@alberich.amd.com>
Date:	Mon, 9 Mar 2009 11:30:42 +0100
From:	Andreas Herrmann <andreas.herrmann3@....com>
To:	Jike Song <albcamus@...il.com>
CC:	Dragoslav Zaric <dragoslav.zaric.kd@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Linux* Processor Microcode Data File

On Mon, Mar 09, 2009 at 06:00:35PM +0800, Jike Song wrote:
> On Mon, Mar 9, 2009 at 5:43 PM, Dragoslav Zaric
> <dragoslav.zaric.kd@...il.com> wrote:
> > Hello,
> >
> > I was browsing Intel web site for my processor docs and I bumped
> > on download link "Linux* Processor Microcode Data File" and it says
> > there:
> >
> > "The microcode data file contains the latest microcode definitions for
> > all Intel processors.
> > Intel releases microcode updates to correct processor behavior as
> > documented in the respective
> > processor specification updates. While the regular approach to getting
> > this microcode update is via
> > a BIOS upgrade, Intel realizes that this can be an administrative
> > hassle. The Linux Operating System
> > and VMware ESX products have a mechanism to update the microcode after
> > booting. For example,
> > this file will be used by the operating system mechanism if the file
> > is placed in the /etc/firmware
> > directory of the Linux system."
> >
> > So, does new kernel versions just copy this microcode update file in
> > /etc/firmware folder or new
> > instructions are replaced in assembly code ?
> >
> 
> Linux provides an microcode driver for Intel & AMD CPUs:
> 
>     arch/x86/kernel/microcode_*
> 
> and there is a service called "microcode_ctl" to open it and write the
> microcode on every starting.   Where to find the microcode data is
> this service specified, and the kernel doesn't care it.  You may want
> to find:

> http://www.urbanmyth.org/microcode/

FYI, microcode patch loading for AMD CPUs uses only the firmware
loader interface. The patches for AMD CPUs are available from

http://www.amd64.org/support/microcode.html


Regards,
Andreas

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