From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Alexander E. Patrakov" <patrakov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH] dracut: add support for updating the CPU microcode
Date: Sat, 16 Apr 2016 20:20:10 +0500
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To: Guido Trentalancia <guido-D1bseh+SzQhuxeB9wqlrNw@public.gmane.org>, Andrei Borzenkov <arvidjaar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, initramfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

16.04.2016 18:54, Guido Trentalancia =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> Hello Andrei,
>
> thanks for getting back on this...
>
> On Sat, 16/04/2016 at 09.01 +0300, Andrei Borzenkov wrote:
>> 16.04.2016 02:18, Guido Trentalancia =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>>> This is the initial version of a new "microcode" dracut module
>>> that can be used to update the microcode on Intel(R) CPUs.
>>>
>>
>> ??? dracut already supports early microcode loading, why it is not
>> enough and what problem this patch solves?
>
> To be honest, I didn't notice it. I was expecting such support, if
> available, to be a module and I couldn't find it, so I wrote it.
>
> However, I have noticed it is much simpler than the actual
> implementation. It doesn't differentiate between Intel and AMD (why i=
t
> should ?), it just loads the microcode in the standard location as
> defined by the microcode update utility.

The microcode update utility stopped working when a Haswell microcode=20
update got released that makes some CPU instructions illegal (because=20
they didn't work properly in the first place). Please see=20
http://bugs.debian.org/762195

Sure, glibc no longer uses these instructions, but now (exactly to avoi=
d=20
repetition of this bug) the only supported way to update the microcode=20
is to place it in the initcpio so that "early microcode update" in the=20
kernel loader notices it.

--=20
Alexander E. Patrakov