linux-kernel - Re: [PATCH 1/2] x86/microcode/intel: Refresh the revisions that determine old

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Message-ID: <f47826f2-9cb2-421e-91b8-fd5a435dd531@intel.com>
Date: Tue, 19 Aug 2025 12:07:42 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Sohil Mehta <sohil.mehta@...el.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 Borislav Petkov <bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
 Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
 Nikolay Borisov <nik.borisov@...e.com>,
 Alex Murray <alex.murray@...onical.com>, linux-kernel@...r.kernel.org,
 stable@...nel.org
Subject: Re: [PATCH 1/2] x86/microcode/intel: Refresh the revisions that
 determine old_microcode

On 8/19/25 11:28, Pawan Gupta wrote:
>> Alas, these deletions are documented as well as everything else is in
>> the changelog...
> Should this file reflect those deletions as well? As an example, if an
> ancient part gets removed from the microcode repo, it may still be worth
> for Linux to keep the record of its last microcode version.

<sigh>

There's even a "Removed Platforms" section in the microcode repo
changelogs that gets copied and pasted for each release. But it's not
consistently updated as platforms are removed.

But, thanks to the magic of git, we can just look for the removed files:

06-55-06
06-cf-01
06-8f-05
06-8f-06
06-ba-08
06-8f-04
06-86-04
06-86-05

.. that never came back in a later version. It might be a fun exercise
to run through those and see if any of them matter.

We could always reconstruct the .h file from *all* of the microcode
repo's git history. It's just scripting. But we better be doing it for a
real reason.

If folks have one of these preproduction CPUs, they've got much bigger
problems that being warned about old microcode. If we think it's the
kernel's job to tell folks about these, I'd rather it be some other
mechanism than the old_microcode one.

For instance, we could make a x86_cpu_id[] that lists these and taints
if they're ever seen.

So, let's just ignore this issue for now. I'm not convinced it's a
practical problem.