Handling commit change logs (was: [PATCH v3 13/15] cpufreq: Add cpufreq driver for Tegra124)

Andreas Färber afaerber at suse.de
Wed Aug 20 13:02:28 PDT 2014

Hi Javier,

Am 20.08.2014 17:39, schrieb Javier Martinez Canillas:
> As you already know when you apply a patch with git am, everything
> that is between a line with 3 dashes line (---) and the actual diff is
> omitted since that is where the generated diffstat is placed by git
> format-patch.
> We usually rely on that behavior to put there the history of a patch
> or any information that we think that is useful for reviewers but is
> not suitable to end in the commit message. Now that means that you
> have to generate the patch and then manually edit it to add the
> history there.
> But since git am omits any text between the first "---" and the diff,
> it means that you can add a "---" on your actual commit message and
> anything that follows will be discarded by git am, that way you can
> maintain your history on your commit message which is way less tedious
> than manually editing patches.
> So the second "---" from Tuomas patch is actually the one generated by
> git format-patch but that gets discarded by git am just like any other
> text so it causes no harm when other apply the patches.
> If this not the correct workflow and you have a better way to manage
> this, I would love to know about it.

One drawback of having --- in the commit message is that you can't
cherry-pick but really need to use git-am for it to be stripped.

I resorted to a scripted way of handling change logs: Per patch series I
maintain a shell script that after git-format-patch essentially runs
sed -i "/---/ r /dev/stdin" $OUTDIR/0001-*.patch <<EOCL
to insert my text after ---. (sed syntax is not POSIX-compliant FWIW.)
Similarly I fill in the blurbs for the cover letter.

Another way I've heard of is git-notes, which lets you associate text
with a given commit id.
But in my tests that data did not survive a git-rebase -i, it stayed
attached to the original commit when editing the commit message or
fixing up a patch. It could still be accessed through the list of
git-notes but not be comfortably extracted from the updated branch via
git-rev-list or the likes.


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