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Date: Wed, 5 Feb 2020 21:48:41 +0000
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] Revert kheaders feature
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To: Joel Fernandes <joel@joelfernandes.org>
Cc: Olof Johansson <olof@lixom.net>, Alexei Starovoitov <ast@kernel.org>, Masahiro Yamada <masahiroy@kernel.org>, Michal Marek <michal.lkml@markovi.net>, Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>, Tejun Heo <tj@kernel.org>, Mauro Carvalho Chehab <mchehab+samsung@kernel.org>, David Howells <dhowells@redhat.com>, Patrick Bellasi <patrick.bellasi@arm.com>, Krzysztof Kozlowski <krzk@kernel.org>, linux-kbuild@vger.kernel.org, "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>

On Wed, Feb 05, 2020 at 01:35:56PM -0800, Joel Fernandes wrote:
> On Wed, Feb 5, 2020 at 1:33 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> [snip]
> > > > like the BTF approach is significantly better and said users are
> > > > hopefully moving forward to it quickly, and if they can't move
> > > > forward, then they're likely also not going to move forward to newer
> > > > kernels either?
> > >
> > > I think BCC runs on a lot of upstream machines. I think the migration
> > > strategy is a matter of opinion, one way is to take it out and cause some
> > > pain in the hope that users/tools will migrate soon (while probably carrying
> > > the reverted patches out of tree). Another is to migrate the tools first and
> > > then take it out (which has its own disadvantages such as introducing even
> > > more users of it while it is still upstream).
> >
> > Do we "know" what tools today require this, and what needs to be done to
> > "fix" them?  If we don't know that, then there's no way to drop this,
> > pretty much ever :(
> 
> Is there a real reason to drop it or a problem dropping this solves though?

Olof had some reasons, but as we were drinking at the time when it came
up last night, I can't really remember them specifically.  Hopefully he
does :)

But that didn't answer my question of "who is still using this"?  I was
hoping we actually knew this given it was created for specific users.

thanks,

greg k-h