linux-kernel - Re: [PATCH] Fix booting pentium+ with dodgy TSC

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Message-ID: <20080406112207.GA26510@elte.hu>
Date:	Sun, 6 Apr 2008 13:22:08 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <ak@...e.de>, "H. Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org, lguest <lguest@...abs.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] Fix booting pentium+ with dodgy TSC

* Rusty Russell <rusty@...tcorp.com.au> wrote:

> Linus please apply.  Almost by definition this patch can't make things 
> worse.

well, while i agree with the patch it could make things worse. In this 
case it can cause code that has been compiled to rely on TSC to 
malfunction. For if sched_clock() was using cpu_has_tsc it could return 
0 all the time, breaking the scheduler without the user having a clear 
idea why it broke. It isnt, and sched_clock() will work fine, but still, 
your "this cant make things worse" statement is not completely correct. 

In any case:

 Acked-by: Ingo Molnar <mingo@...e.hu>

and i've also queued it up into the for-.25 queue of x86.git.

	Ingo
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