linux-kernel - Re: [RFC PATCH 0/15] x86: Remove support for TSC-less and CX8-less CPUs

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Message-ID: <8C172B63-38E1-427B-8511-25ECE5B9E780@alien8.de>
Date: Thu, 08 May 2025 22:11:52 +0200
From: Borislav Petkov <bp@...en8.de>
To: "Maciej W. Rozycki" <macro@...am.me.uk>
CC: "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
 linux-kernel@...r.kernel.org, "Ahmed S . Darwish" <darwi@...utronix.de>,
 Andrew Cooper <andrew.cooper3@...rix.com>, Ard Biesheuvel <ardb@...nel.org>,
 Arnd Bergmann <arnd@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>,
 John Ogness <john.ogness@...utronix.de>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>,
 John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Subject: Re: [RFC PATCH 0/15] x86: Remove support for TSC-less and CX8-less CPUs

On May 8, 2025 4:51:27 PM GMT+02:00, "Maciej W. Rozycki" <macro@...am.me.uk> wrote:
>On Tue, 6 May 2025, Borislav Petkov wrote:
>
>> >  Doesn't work for ongoing driver maintenance
>> 
>> Dunno, I'd concentrate my efforts on something, a *little* *bit* more modern.
>> At some point this is old rusty hw no matter from which way you look at it and
>> it might as well be left to rest in its sunset days.
>
> One doesn't exclude the other.  I do POWER9 or RISC-V stuff too.  Isn't 
>it modern enough?
>
>> What I have problem with is wasting my time maintaining old, ancient hw which
>> is not worth the electricity it needs to run. Especially if you can get
>> something orders of magnitudes better in *any* aspect you can think of, and
>> actually get some real work done.
>
> I don't want you let alone expect to waste time on anything you're not 
>interested in.  I'm trying to find a solution that saves you from that 
>while preferably keeping everyone happy enough, including myself.
>
> Real work?  I find engineering challenges enjoyable regardless of the age 
>of hardware involved and I don't want to take away anyone's daily bread 
>(including mine) by spending my free time on a project someone might have 
>commercial interest in and should pay for.  An obsolete platform is ideal 
>for this purpose.
>
> And what's better and what's not is subjective.  I don't find all the new 
>stuff better, just as I don't all the old stuff.  At least the old gear 
>tends to be sturdy (once you've contained issues with the PSU) and likely 
>won't suffer from electromigration in a few years' time.  It can be easier 
>to repair too if a component does fail.
>
> NB people also fancy old cars, or boats, or trains even, not because 
>they're faster, more comfortable, or have any real advantage over modern 
>alternatives.

This fits very well, IMO, with Linus' suggestion to support this stuff out of tree. I think this solution is the optimal one for all parties involved...

-- 
Sent from a small device: formatting sucks and brevity is inevitable.