linux-kernel - Re: PATCH: Allow user to force 'tsc' to be treated as stable.

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Message-ID: <alpine.LFD.2.00.0902062040000.22800@localhost.localdomain>
Date:	Fri, 6 Feb 2009 20:40:31 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Ben Greear <greearb@...delatech.com>
cc:	Jiri Kosina <jkosina@...e.cz>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	rusty@...tcorp.com.au
Subject: Re: PATCH: Allow user to force 'tsc' to be treated as stable.

On Fri, 6 Feb 2009, Ben Greear wrote:

> Jiri Kosina wrote:
> > On Thu, 5 Feb 2009, Ben Greear wrote:
> > 
> > > Allow user to force TSC as stable clock-source. Works around BIOS issues
> > > in the FWA-7304 (Via CN700 chipset) system, and possibly others.
> > 
> > How do you know that the TSC is stable on such system? What was the reason
> > for kernel marking it unstable?
> 
> I've used it for a timing source in my own modules and it has
> worked well.  It could still be broken in some way, but if so,
> I'm not sure how to detect it.  Ingo sent me a program to test
> the tsc, and at least for short runs, it showed no problem.
> 
> Another person suggested the system might think it is unstable
> because I have ACPI disabled in my BIOS and that might cause
> the kernel not to have a 'PM timer' that it uses to check the
> tsc?
> 
> Other than that, I have no idea why the kernel thinks the tsc
> is unstable.

Can you please provide the dmesg output, so I can see in which context
this happens.

Thanks,

	tglx
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