RE: Linux Kernel Microcode Question

From: Nakajima, Jun (jun.nakajima_at_intel.com)
Date: 03/18/04

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    Date:	Thu, 18 Mar 2004 09:19:42 -0800
To: "Justin Piszcz" <jpiszcz@hotmail.com>, <linux-kernel@vger.kernel.org>

    A microcode update is used to correct errata in the processor, and the
    facility is part of the architecture, as written in the manual. As Dave
    pointed out, if the BIOS has the latest one, the OS does not need to do
    anything.

    We are working with Tigran closely, and we have provided the latest
    updates to him very recently. He will try them out first, and then
    publish the new updates for public consumption. Stay tuned.

    Jun

    >-----Original Message-----
    >From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
    >owner@vger.kernel.org] On Behalf Of Justin Piszcz
    >Sent: Thursday, March 18, 2004 8:41 AM
    >To: linux-kernel@vger.kernel.org
    >Subject: Linux Kernel Microcode Question
    >
    >The URL: http://www.urbanmyth.org/microcode/
    >
    >The microcode_ctl utility is a companion to the IA32 microcode driver
    >written by Tigran Aivazian <tigran@veritas.com>. The utility has two
    uses:
    >
    > * it decodes and sends new microcode to the kernel driver to be
    >uploaded
    >to Intel IA32 processors. (Pentium Pro, PII, PIII, Pentium 4, Celeron,
    Xeon
    >etc - all P6 and above, which does NOT include pentium classics)
    > * it signals the kernel driver to release any buffers it may hold
    >
    >The microcode update is volatile and needs to be uploaded on each
    system
    >boot i.e. it doesn't reflash your cpu permanently, reboot and it
    reverts
    >back to the old microcode.
    >
    >My question is, what are the advantages vs disadvantages in updating
    your
    >CPU's microcode?
    >
    >Is it worth it?
    >
    >Does it matter what type of Intel CPU you have?
    >
    >Do some CPU's benefit more than others for microcode updates?
    >
    >I know RedHat distributions usually do this by default, but others do
    not.
    >
    >Can anyone explain reasons to or not to update the CPU microcode?
    >
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    Relevant Pages

    • Re: Perpetual re:booting
      ... Prescott processors on boards which do not fully support them. ... the processor microcode is not updating correctly. ... allow the machine to boot up with whatever microcode update the BIOS has ... The microcode version is identified by this utility as "CPU Revision" ...
      (microsoft.public.windowsxp.accessibility)
    • Re: How can I reinstall "microcode update device" (in device manager)?
      ... the "microcode update device" icon disappeared. ... Normally, your BIOS will look through its collection of microcode files, ... If you install that program and run it, then go to the "CPUID" tab, it gives ...
      (microsoft.public.windowsxp.hardware)
    • Re: How can I reinstall "microcode update device" (in device manag
      ... How can I reinstall the "microcode update device"? ... Normally, your BIOS will look through its collection of microcode files, ... If you install that program and run it, then go to the "CPUID" tab, it gives ...
      (microsoft.public.windowsxp.hardware)
    • Re: MicroCode???
      ... on CPUs with loadable microcode the microcode is _not_ permanent but loaded during initialization. ... On x86 systems with loadable microcode this code is part of the computers BIOS and as I already said gets loaded during the CPU initialization during POST. ... Needless to say even the MS knowledge base seem to know nothing from a microcode update within SP2. ... that the upgrade is done during runtime and it temp. ...
      (comp.sys.intel)
    • Re: A quote from Crypto-Gram
      ... Check out chapter 9.11 "Microcode Update Facilities". ... It existed and is used since Pentium 2. ... The maximum size of the microcode update block on the Pentium is 2 KB ... instructions or only affects specific instructions. ...
      (sci.crypt)