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

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Message-ID: <cbd74335-055d-46e5-9dc3-9197ff95cebf@intel.com>
Date: Tue, 19 Aug 2025 09:13:27 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: Andrew Cooper <andrew.cooper3@...rix.com>, Pawan Gupta
	<pawan.kumar.gupta@...ux.intel.com>
CC: 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>, Dave Hansen
	<dave.hansen@...el.com>, Nikolay Borisov <nik.borisov@...e.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 8/19/2025 4:18 AM, Andrew Cooper wrote:
> On 19/08/2025 6:19 am, Pawan Gupta wrote:
>> On Mon, Aug 18, 2025 at 12:01:36PM -0700, Sohil Mehta wrote:
>>> Update the minimum expected revisions of Intel microcode based on the
>>> microcode-20250512 (May 2025) release.
>>>
>>> Cc: <stable@...nel.org> # v6.15+
>>> Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
>>> ---
>>>  .../kernel/cpu/microcode/intel-ucode-defs.h   | 86 +++++++++++--------
>>>  1 file changed, 48 insertions(+), 38 deletions(-)
>>>
>> ".model = 0x55, .steppings = 0x0040" is being removed? Total number of
>> entries in the table are being reduced by ~10.
> 

Based on the diff stat, aren't the total entries increasing by 10?

> That's because early in a CPUs lifecycle, microcode for the late
> pre-production steppings are still included in the public repo, but
> eventually dropped.
> 
> Alas, these deletions are documented as well as everything else is in
> the changelog...
> 

I sorted the file by FMS to make it easier to spot changes going
forward. Though, I don't think we can rely on the kernel history to
track the microcode changes. Because there isn't a direct 1:1 mapping
between the microcode releases and the kernel update. (Unless that's
what you are proposing)

Dave's initial commit used the Nov 2024 release, and this one is based
on May 2025. There could potentially be multiple releases in the middle
that added and removed stuff which would go unnoticed. Though, using the
script in patch 2 it should be easy to track that (outside the kernel)
if really needed.


> ~Andrew