Re: Linux 2.6.21-rc1

From: Daniel Walker
Date: Wed Feb 21 2007 - 16:26:42 EST

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..


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