[Ubuntu-bugcontrol] Proposed update for https://wiki.ubuntu.com/Kernel/KernelBisection inquiry

[Andy Whitcroft]

On Mon, Dec 23, 2013 at 11:37:55AM -0600, Christopher M. Penalver wrote:
> Hello everyone. I wanted to e-mail you to get your feedback on a
> proposed draft for updating the end of the KernelBisection article
> (which has been remarkably successful in enabling new and experienced
> bisectors to bisect their own kernel regressions).
> 
> The high level for this proposed draft is that a common event for bug
> reporters is they want to test a patch not available in an upstream
> tree (ex. linux-stable). However, they tend to get quite confused on
> what to do step-by-step (as I was when I was Googling it all out). I
> didn't find any article with a comprehensive click-for-click example,
> I had to pick out what I needed from a number of articles, and dig
> through a ton that were largely useless or didn't apply.
> 
> Hence, while the proposed draft would fit the logical flow of the
> article placed at the end, as when one has finished commit bisecting
> and an upstream patch was submitted but not merged, it may be better
> placed in a different article, but I haven't really found one at this
> point.
> 
> What do you think?
> 
> -START-
> = Testing a patch from upstream =
> 
> Lets assume you may have identified an upstream patch that hasn't been
> commited to an upstream branch, and you would like to test it out. Let
> us take as an example the following upstream patch:
> 
> testfix.patch
> http://www.spinics.net/lists/linux-acpi/msg47755.html
> 
> Start copying from the line where it notes:
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> 
> to the last code line before the double dash:
>  static int register_count;
> 
> Your patch file should exactly as shown, honoring all spaces, or lack thereof:

You shuldn't need to rip the above and below bits as git should understand
it in full (as patch has always done too).  Indeed if it has a 'diff
--git' header then it is in git email format.  Saving the email as a
file and applying it with 'git am <filename>' will apply it including
the right ownership.

> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index 995e91b..b3032f8 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -85,7 +85,7 @@ module_param(allow_duplicates, bool, 0644);
>   * For Windows 8 systems: if set ture and the GPU driver has
>   * registered a backlight interface, skip registering ACPI video's.
>   */
> -static bool use_native_backlight = false;
> +static bool use_native_backlight = true;
>  module_param(use_native_backlight, bool, 0644);
> 
>  static int register_count;
> 
> save this file to your Desktop as testfix.patch. Then execute at a terminal:
> git config --global user.email "you at example.com" && git config
> --global user.name "Your Name" && git clone
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
> ~/Desktop/linux-stable && patch
> ~/Desktop/linux-stable/drivers/acpi/video.c ~/Desktop/testfix.patch &&
> git add . && git commit
> 
> Now in the new window type: {{{
> example }}}
> 
> press Ctrl+O -> Enter -> Ctrl+X. Then, type at a terminal:
> git log -n 1 | grep commit
> 
> which should post the commit:
> commit <COMMIT>
> 
> Use this commit in the below terminal command:
> git checkout <COMMIT> && cp /boot/config-`uname -r` .config && yes ''

If you just committed the patch it would be the currnet commit, so there
would be no reason to check it out again.

> | make oldconfig && make-kpkg clean && CONCURRENCY_LEVEL=`getconf
> _NPROCESSORS_ONLN` fakeroot make-kpkg --initrd
> --append-to-version=-custom2 kernel_image kernel_headers && cd .. &&
> sudo dpkg -i *.deb
> 
> If for whatever reason the new kernel doesn't boot, it may not be you
> did something wrong, but just that it won't boot with this commit
> applied.

-apw