Re: [regression] microcode files missing in initramfs imgages from dracut (was Re: [PATCH] x86: Clean up remaining references to CONFIG_MICROCODE_AMD)

From: Borislav Petkov <bp@alien8.de>
To: Linux regressions mailing list <regressions@lists.linux.dev>
Cc: lukas.bulwahn@gmail.com, dave.hansen@linux.intel.com,
	hpa@zytor.com, kernel-janitors@vger.kernel.org,
	linux-kernel@vger.kernel.org, mingo@redhat.com,
	tglx@linutronix.de, x86@kernel.org
Subject: Re: [regression] microcode files missing in initramfs imgages from dracut (was Re: [PATCH] x86: Clean up remaining references to CONFIG_MICROCODE_AMD)
Date: Sun, 12 Nov 2023 19:10:36 +0100	[thread overview]
Message-ID: <20231112181036.GBZVEVHIIj/Oos1cx4@fat_crate.local> (raw)
In-Reply-To: <c67bd324-cec0-4fe4-b3b1-fc1d1e4f2967@leemhuis.info>

On Sun, Nov 12, 2023 at 04:03:32PM +0100, Linux regression tracking (Thorsten Leemhuis) wrote:
> That's because dracut until the recent commit
> https://github.com/dracutdevs/dracut/commit/6c80408c8644a0add1907b0593eb83f90d6247b1
> looked for CONFIG_MICROCODE_AMD and CONFIG_MICROCODE_INTEL in the config
> file to decide what to include or not.

They've been told a bunch of times already that grepping .config for
specific symbols is not how one should check whether one should add
microcode blobs to the initrd or not because Kconfig symbols are not an
ABI.

And looking at that commit, now they're grepping for CONFIG_MICROCODE.
And that'll break again if one day we decide to make the microcode
loader built in unconditionally.

How to fix this reliably and properly?

Honestly, I don't have a good idea. If we do something like this:

grep microcode_init System.map

then that makes "microode_init" ABI and we won't be able to change it
eva. I'd need to do some digging here...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette