On Tue, Oct 22, 2019 at 02:11:22PM +0200, Vegard Nossum wrote:

As I wrote in there, we could already today start using

  git am --message-id

when applying patches and this would provide something that a bot could
annotate with git notes pointing to lore/LKML/LWN/whatever. I think that
would already be a pretty nice improvement over today's situation.

Sadly, since the beginning of 2018, this was only used for a measly
~0.14% of all non-merge commits in the kernel:

$ git rev-list --count --no-merges --since='2018-01-01' --grep 'Message-Id:
' linus/master
178

You might also want to count commits which have a link tag with a
Message-Id:

Link: https://lore.kernel.org/r/c3438dad66a34a7d4e7509a5dd64c2326340a52a.1571647180.git.mbobrowski@mbobrowski.org (local)

That's because some kernel developers have been using a hook script like this:

#!/bin/sh
# For .git/hooks/applypatch-msg
#
# You must have the following in .git/config:
# [am]
#	messageid = true
	
. git-sh-setup
perl -pi -e 's|^Message-Id:\s*<?([^>]+)>?$|Link: https://lore.kernel.org/r/$1|g;' "$1"
test -x "$GIT_DIR/hooks/commit-msg" &&
	exec "$GIT_DIR/hooks/commit-msg" ${1+"$@"}
:

.... as we had reached rough consensus that this was the best way to
incorprate the message id (since it could made to be a clickable link
in tools like gitk, for example).  This rough consensus has only been
in place since around the time of the Maintainer's Summit in Lisbon,
so uptake is still probably a bit slow.  I'd expect to see a lot more
of this in the next merge window, though.

						- Ted