linux-kernel - Re: TSC problems with Acer TravelMate 5735Z

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Message-ID: <20200524185800.GV325280@hirez.programming.kicks-ass.net>
Date:   Sun, 24 May 2020 20:58:00 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     x86@...nel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: TSC problems with Acer TravelMate 5735Z

On Sun, May 24, 2020 at 07:09:18PM +0200, Paul Menzel wrote:
> Dear Linux folks,
> 
> 
> I got my hands on an old Acer TravelMate 5735Z (Intel GM45/Cantiga) and
> installed Debian Sid/unstable with Linux 5.6.7 on it.
> 
> Booting the system it takes a long time, and the systemd units fail to
> start. The logs contain that the TSC is unstable. Adding `tsc=unstable` to
> the Linux kernel command line fixes this.

It fixes nothing; it just doesn't get you the warning because you told
it upfront.

> Do you have an idea, what might cause this? 

Yes, but you didn't include the dmesg of the affected case. IIRC it
actually spells it out for you.

> Do you have an idea, what might cause this, 

It's a Core2, Core2 doesn't have stable TSC.

> and how it can be fixed?

Use a 'better' CPU :-)