Re: [PATCH v2] x86/tsc: Set X86_FEATURE_TSC_RELIABLE to skip refined calibration

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] x86/tsc: Set X86_FEATURE_TSC_RELIABLE to skip refined calibration
Date	2016-10-12 10:00 +0200
Message-ID	<srmCe-1kH-7@gated-at.bofh.it> (permalink)
References	(1 earlier) <s9Ccp-8hd-13@gated-at.bofh.it> <sa60O-3vb-23@gated-at.bofh.it> <samoV-5D1-5@gated-at.bofh.it> <sanbj-6aB-7@gated-at.bofh.it> <srctb-3jq-9@gated-at.bofh.it>
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On Tue, 11 Oct 2016, Bin Gao wrote:
> On Fri, Aug 26, 2016 at 12:14:58PM +0200, Thomas Gleixner wrote:
> 
> The Linux kernel does think a reliable calibration implies the reliability (i.e.
> no watchdog required). I'm posting some code pieces to explain.

I know that and I know exactly how all that works. And I certainly did not
ask for an explanation of the current state of affairs. Here is what I
wrote:

> > Second thoughts. We should seperate the calibration aspect from the reliablity
> > aspect.
> > 
> > If a MSR/CPUID readout provides reliable calibration then this does not tell
> > us about the reliablity (i.e. no watchdog required). So having two flags for
> > this - and sure you can set both on those SoCs is the proper solution.

In other words: I want to have two seperate flags:

1) FEATURE_KNOWN_FREQUENCY     - Grab the frequency from CPUID/MSR or whatever
   			       	 and skip the whole calibration thing

2) FEATURE_RELIABLE	       - Do not invoke the watchdog

Thanks,

	tglx

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Re: [PATCH v2] x86/tsc: Set X86_FEATURE_TSC_RELIABLE to skip refined  calibration Bin Gao <bin.gao@linux.intel.com> - 2016-10-11 23:10 +0200
  Re: [PATCH v2] x86/tsc: Set X86_FEATURE_TSC_RELIABLE to skip refined  calibration Thomas Gleixner <tglx@linutronix.de> - 2016-10-12 10:00 +0200

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