linux-kernel - Re: [PATCH] x86/microcode: Fix crashes on early 486 CPUs due to usage of 'cpuid'.

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Message-ID: <CANpbe9Vyss7wEd0rQA7Z=mfi6WTkm5JjCJjTkcsqGCd0mGA2aw@mail.gmail.com>
Date: Mon, 7 Apr 2025 16:28:29 +0200
From: Oerg866 <oerg866@...glemail.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Kevin Koster <lkml@...ertech.com>, Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org, 
	Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86/microcode: Fix crashes on early 486 CPUs due to usage
 of 'cpuid'.

Thank you for your discussions,
I'm happy that a fix for this is happening after all :)

FYI, the link above containing files to easily reproduce in an emulator
*should* still work, so if anyone else wants to see this virtual "rust",
for some reason, go ahead - Even includes the genuine BIOS startup, haha.

I must say that it's quite extraordinary how well the kernel runs on a
486. Wish the same could be said for userspace...

I know my voice really doesn't matter, but I would love for 486
support to remain intact. It's an invaluable help for people who tinker
with old stuff but have grown accustomed to modern tools and habits...

One of my projects uses a modern Linux kernel to install Windows 9x (sorry!)
onto a legacy (or modern, if that's your thing) systems, including
magical things like VESA Local Bus 486 systems, way faster than the
official MS installer ever could. There's quirks here and there, especially
with regards to libata and obscure IDE/SCSI controllers, but other than
that the kernel does its job and it does it extremely well.

I've been experimenting with kernel versions and I'm happy to report that
since 4.x there hasn't been any sort of noticeable performance regression
on old systems like that.

Also some newly written BIOS / DOS driver code could not have happened
if Linux wasn't such an excellent reference. Well written drivers for
the old stuff can practically compensate for the lack of datasheets for
example.

I think that's something worth applauding, even if some may think it's
better to throw the old stuff "in the garbage" ;)

Sorry I'm rambling a bit :) Anyway - Thanks for your efforts everyone.

See you next patch!

Eric Voirin