Subject: Re: How to debug linux-next? (was: Re: xorg problems with v2.6.27-rc1-2457-gdcb80fd)

From: Stephen Rothwell <[email-masked]>
Date: Thu, 31 Jul 2008 23:35:58 +1000

On Thu, 31 Jul 2008 15:23:44 +0200 Nico -telmich- Schottelius <[email-masked]> wrote:
>
> Some questions about using and debugging linux-next:
> 
> - Where to report errors? to this ml? cc-ing the related subsystem
>   maintainer(s)?

Yes.

> - What's the normal way of finding out the source for a problem, if you know
>   a good commit (9bead9ae16728973cd31d9fd60c496e0e2fabbd1) and a
>   bad commit (dcb80fdb8cffd3fa06cd322b3e8227632ec23597)?

It is much easier to use "git bisect" within a single linux-next release
than between releases.  The latter should work some of the time but is
complicated by the fact that linux-next is effectively rebased every
day.  So it is sensible to see if the "stable" branch of linux-next works
(as that is just Linus' tree) and use that as a "good" starting point if
so.  If that doesn't work, then the problem is in Linus' tree already.

> - As far as I can see, you are doing rebase on linux-next. Why don't you
>   continue to do git-merge?

Because some of the trees that are merged into linux-next are rebased
fairly often as well.

> - And would a non-rebased tree not make life much easier for debugging
>   purposes?

I don't know.  What it would do is produce a lot more merge conflicts as
patches are moved around, changed, removed etc on a daily basis.

> My motivation is to find out the reason why xorg crashes now together
> with the xorg guys. But currently it seems to be impossible for me to
> detect which commits have been between to snapshots of the master
> branch of linux-next.

Yeah, that is a pain.  Does Linus' tree work?

-- 
Cheers,
Stephen Rothwell                    [email-masked]
http://www.canb.auug.org.au/~sfr/