Subject: Re: [PATCH v2] docs: bug-bisect: add a note about bisecting -next

From: Stephen Rothwell <[email-masked]>
Date: Fri, 1 Nov 2024 22:59:16 +1100

Hi Thorsten,

Thanks for this.  A couple of comments.

On Fri,  1 Nov 2024 07:17:06 +0100 Thorsten Leemhuis <[email-masked]> wrote:
>
> Explicitly mention how to bisect -next, as nothing in the kernel tree
> currently explains that bisects between -next versions won't work well
> and it's better to bisect between mainline and -next.
> 
> Co-developed-by: Mark Brown <[email-masked]>
> Signed-off-by: Mark Brown <[email-masked]>
> Reviewed-by: Mark Brown <[email-masked]>
> Signed-off-by: Thorsten Leemhuis <[email-masked]>
> ---
> v2:
> - slightly change patch descption
> - make the text more how-toish to better match the rest of the document
> 
> v1: https://lore.kernel.org/all/[email-masked]/
> - initial release
> ---
>  Documentation/admin-guide/bug-bisect.rst | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/Documentation/admin-guide/bug-bisect.rst b/Documentation/admin-guide/bug-bisect.rst
> index 585630d14581c7..47264c199247e6 100644
> --- a/Documentation/admin-guide/bug-bisect.rst
> +++ b/Documentation/admin-guide/bug-bisect.rst
> @@ -108,6 +108,27 @@ a fully reliable and straight-forward way to reproduce the regression, too.*
>  With that the process is complete. Now report the regression as described by
>  Documentation/admin-guide/reporting-issues.rst.
>  
> +Bisecting linux-next
> +--------------------
> +
> +If you face a problem only happening in linux-next, bisect between the
> +linux-next branches 'stable' and 'master'. The following commands will start
> +the process for a linux-next tree you added as a remote called 'next'::
> +
> +  git bisect start
> +  git bisect good next/stable
> +  git bisect bad next/master
> +
> +The 'stable' branch refers to the state of linux-mainline the current
                                                             ^
                                                             that the current

> +linux-next release (found in the 'master' branch) is based on -- the former
> +thus should be free of any problems that show up in -next, but not in Linus'
> +tree.

As you say, 'stable' only works for the current linux-next release.  If
you are trying to bisect a previous release, you can always find the
SHA1 associated with the base of any linux-next release using "grep
origin Next/SHA1s".  Not sure how useful that is.

-- 
Cheers,
Stephen Rothwell