Re: [RFC] Provide in-kernel headers for making it easy to extend the kernel

From: Joel Fernandes <joel@joelfernandes.org>
To: hpa@zytor.com
Cc: "Enrico Weigelt, metux IT consult" <lkml@metux.net>,
	Greg KH <gregkh@linuxfoundation.org>,
	Daniel Colascione <dancol@google.com>,
	Pavel Machek <pavel@ucw.cz>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	ast@kernel.org, atish patra <atishp04@gmail.com>,
	Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
	Jan Kara <jack@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
	Karim Yaghmour <karim.yaghmour@opersys.com>,
	Kees Cook <keescook@chromium.org>,
	kernel-team@android.com,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Manoj Rao <linux@manojrajarao.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	rostedt@goodmis.org, Thomas Gleixner <tglx@linutronix.de>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>,
	yhs@fb.com
Subject: Re: [RFC] Provide in-kernel headers for making it easy to extend the kernel
Date: Thu, 7 Mar 2019 22:16:23 -0500	[thread overview]
Message-ID: <20190308031623.GA129529@google.com> (raw)
In-Reply-To: <6773AB0F-C197-4465-80D2-3F7DA28EF790@zytor.com>

On Thu, Mar 07, 2019 at 03:40:37PM -0800, hpa@zytor.com wrote:
> On March 7, 2019 3:12:07 PM PST, Joel Fernandes <joel@joelfernandes.org> wrote:
> >Enrico,
> >
> >On Thu, Mar 07, 2019 at 11:11:22PM +0100, Enrico Weigelt, metux IT
> >consult wrote:
> >> On 07.03.19 21:55, Greg KH wrote:
> >> 
> >> > Ick, no, no more squashfs please, let's just kill that mess once
> >and for
> >> > all :)
> >> 
> >> okay, then: s/squashfs/whatever_fs_image_or_archive_you_like/;
> >> 
> >> > Again, putting this in a simple compressed tar image allows anyone
> >to do
> >> > whatever they need to with this.  If they want a full filesystem,
> >> > uncompress it and use it there.  If they just want it in-memory
> >where
> >> > they can uncompress it and then discard it, that works too.
> >> 
> >> And let me stress the point: doesn't need any kernel changes at all,
> >> when it's just a file in the same place where the .ko's live.
> >
> >Yes, but you're missing the point that some people would also opt to
> >build it
> >into the kernel during their development/debugging (Config=y). For such
> >folks, they don't want to update the FS with anything during debug runs
> >either. Your "whole same place where the .ko lives" doesn't address
> >Daniel's
> >usecase. You may say "initrd", but this is a much cleaner solution to
> >that
> >IMO. There is no initrd needed and the path to the header files will be
> >at a
> >standard location that is already pre-decided by the kernel.
> >
> >As Greg said, you are welcome to keep it disabled for yourself if you
> >don't
> >want it. This doesn't affect anyone else who doesn't use it.
> 
> You do know that initrd can be built into the kernel, right?

Yes of course, Hans. I meant the proposed solution is cleaner than the initrd
(built-in or otherwise). The proc file location is fixed and all tools can
just refer to it than worrying about where in the initrd are the headers
located.

thanks!

 - Joel