Subject: Re: Linux 2.6.21-rc1
From: Daniel Walker <dwalker@mvista.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tglx@linutronix.de,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, mingo@elte.hu
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Date: Wed, 21 Feb 2007 13:23:30 -0800
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On Wed, 2007-02-21 at 13:06 -0800, Linus Torvalds wrote:
> 
> On Wed, 21 Feb 2007, Daniel Walker wrote:
> > 
> > Here's the final commit from the bisect which caused it . It says "No
> > changes to existing functionality" ?
> 
> Ok, it wouldn't be the first time some change that is supposed to change 
> nothing does actually change something.

Yeah , maybe I screwed something up. First time I've done a git bisect.

> That said, one thing to worry about when doing bisection: the kernel 
> configuration.
> 
> If you always just do "make oldconfig" or something, the kernel config for 
> the thing you test will depend on the _previous_ kernel you compiled, and 
> that is not always what you want. I've once had a failing kernel, did 
> bisection, and it turned out that since I had gone back in time to before 
> the option that caused the failure even existed, I had (by mistake) then 
> compiled some of the later kernels without that option enabled, and called 
> them "good". 

In this case I don't think anything was specifically turned on, beyond
SMP. For instance HRT/dynamic tick was off.

I didn't run "make oldconfig", but just running "make" asked for options
that just got added, which was nice.

> The end result: "git bisect" didn't actually end up pointing to the right 
> commit, just because I had effectively lied to it.
> 
> That said, considering that you did get a commit that doesn't look 
> entirely unlikely (and that clearly changes things that are relevant), I 
> suspect you did actually find the right one.

I think if it's not that exact commit it's still one in that set. I
mainly wanted to confirm that it was an hrt/dynamic tick issue , and not
some left field patches..

Daniel

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