linux-kernel - Re: [PATCH 1/3] clocksource: clean up clocksource

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Message-ID: <51D54CBD.1010400@intel.com>
Date:	Thu, 04 Jul 2013 18:21:49 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	hpa@...ux.intel.com, tim.c.chen@...ux.intel.com,
	linux-kernel@...r.kernel.org, andi.kleen@...el.com,
	a.p.zijlstra@...llo.nl, mingo@...e.hu
Subject: Re: [PATCH 1/3] clocksource: clean up clocksource_select


> We need this check and it is completely unrelated to the problem
> you're trying to solve.
> 
> Assume the following:
> 
>        System boots with clocksource A and switches into highres mode.
>        Now clocksource B gets registered and B is not highres capable.
> 
>        clocksource_find_best() selects again A, but we have
>        clocksource=B on the kernel command line to override the kernel
>        decision.
> 
> By removing the check, you install he non highres capable clocksource
> B and kill the machine.
> 

You'r right. my bad, Sorry!

BTW, why we allow user override a second best clocksource? I mean user
can override the tsc with hpet. because undetected unstable tsc?



-- 
Thanks
    Alex
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