[CentOS] /lib/firmware/microcode.dat update on CentOS 6

Thu Jan 18 14:01:06 UTC 2018
Johnny Hughes <johnny at centos.org>

On 01/18/2018 07:51 AM, Phelps, Matthew wrote:
> On Thu, Jan 18, 2018 at 5:03 AM, Johnny Hughes <johnny at centos.org> wrote:
>> On 01/18/2018 03:41 AM, Pete Biggs wrote:
>>>> Look at:
>>>> https://t.co/6fT61xgtGH
>>>> Get the latest microcode.dat file from here:
>>>> https://t.co/zPwagbeJFY
>>>> See how to update the microcode from the links at the bottom of this
>> page:
>>>> https://t.co/EOgclWdHCw
>>>> An before anyone asks .. I have no idea why Red Hat chose this path,
>>>> they did.  It doesn't matter if I (or anyone else) agrees with the
>>>> decision.  It is what it is.
>>> **I'm not blaming you.**
>>> But can I just clarify. We have to *manually* install the microcode
>>> update an EL7 in order to be protected against Spectre? EL6 as well?
>>> Presumably this is to remove RH from the loop and to stop people
>>> blaming them - i.e. this is between Intel and the customer, it's
>>> nothing to do with them.
>> No, this is because at least one major CPU (Intel type 79) is completely
>> broken by the Intel Microcode Update.  Those machines can't boot after
>> the microcode rpm is installed.  It impacts at least these processors:
>> Intel(R) Xeon(R) CPU E5-2637 v4 @ 3.50GHz
>> Intel(R) Xeon(R) CPU E5-2643 v4 @ 3.40GHz
>> Intel(R) Xeon(R) CPU E5-2667 v4 @ 3.20GHz
>> Intel(R) Xeon(R) CPU E5-2667 v4 @ 3.50GHz
>> There may be others.
>> https://bugzilla.redhat.com/show_bug.cgi?id=1532283
>> That means, it is NOT full-proof install and likely leaves many
>> servers/machines broken.  I suppose that the decision is, go pack to
>> what works for all machines (the last known good install) and let admins
>> work with their hardware vendor because the alternative is breaking things.
>> This also needs to be fixed with a combination of firmware updates AND
>> microcode updates.  All of that is outside the expertise of a Linux
>> vendor and is unique for each processor, chipset and firmware combination.
>>> What about future microcode updates? They come out reasonably regularly
>>>  (2 or 3 times a year) - are RH going to absolve themselves from all
>>> future updates because presumably the next update will also contain the
>>> Spectre fixes?
>> How they handle it in the future I have no way of knowing, but if you
>> had 20,000 servers with the impacted CPU and you updated and could not
>> reboot, I would assume that you did not appreciate it.
>>> So, before I re-invent the wheel, does anyone have automation scripts
>>> to do the microcode update? I don't relish the prospect of doing this
>>> manually on a couple of hundred machines. Is it reasonable to grab the
>>> microcode_ctl SRPM and create my own updated RPM to do it?
>> That is what I have found so far with a bit of research.
>> This is NOTHING about who to blame and everything about stable, working
>> updates .. at least it seems so to me.
> So, if we applied the previous microcode update, and all our machines
> rebooted OK, then we don't need to fallback?
> Also, do we know if the updated CentOS microcode RPM reverted the microcode
> for *all* Intel CPUs, or just the ones that had issues? In other words, if
> I apply the latest microcode update to our 100+ machines (which all have
> the previous update, and are OK) will they revert to a vulnerable state?

It reverted for all .. but, your machines may or may not be protected as
only a subset of machines were updated with the original microcode from

It is your call as to what you install .. but the correct method is to
install the current microcode_ctl .. and then research your specific
machine, its CPU, chipset, firmware .. go to the vendor and make sure
you get all the things necessary to mitigate the issues.  It will be
different for each CPU vendor (Intel or AMD), each CPU / Chipset combo,
and even each vendor (Dell may have new firmware for x and y but not z
models, etc.)

There is no one size fits all update for this issue.

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