[PATCH 0/2] Documentation: Add guidance on CONFIG default value

[PATCH 0/2] Documentation: Add guidance on CONFIG default value

[Darren Hart]

From: "Darren Hart (VMware)" <dvhart@infradead.org>

Document the preference for "default n" in kconfig-language.txt, and reference
that in the submit-checklist.rst.

Darren Hart (VMware) (2):
  Documentation/kbuild: Add guidance for the use of default
  Documentation/process: Add CONFIG default value to submit-checklist

 Documentation/kbuild/kconfig-language.txt  | 21 +++++++++++++++++++++
 Documentation/process/submit-checklist.rst |  4 +++-
 2 files changed, 24 insertions(+), 1 deletion(-)

-- 
2.9.4

[PATCH 1/2] Documentation/kbuild: Add guidance for the use of default

[Darren Hart]

From: "Darren Hart (VMware)" <dvhart@infradead.org>

Document the preference [1] for new CONFIG options to "default n" (or
not use default at all) in order to minimizes changes to the config,
especially to avoid "make oldconfig" growing unnecessarily from release
to release.

Document the exceptions where it is acceptable to use "default y/m" for
new CONFIG options.

1. https://lkml.org/lkml/2017/11/18/257

Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <mmarek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
---
 Documentation/kbuild/kconfig-language.txt | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index 262722d..688e41e 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -77,6 +77,27 @@ applicable everywhere (see syntax).
   Optionally, dependencies only for this default value can be added with
   "if".
 
+ The default value deliberately defaults to 'n' in order to avoid bloating the
+ build. With few exceptions, new config options should not change this. The
+ intent is for "make oldconfig" to add as little as possible to the config from
+ release to release.
+
+ Note:
+	Things that merit "default y/m" include:
+
+	a) A new Kconfig option for something that used to always be built
+	   should be "default y".
+
+	b) A new gatekeeping Kconfig option that hides/shows other Kconfig
+	   options (but does not generate any code of its own), should be
+	   "default y" so people will see those other options.
+
+	c) Sub-driver behavior or similar options for a driver that is
+	   "default n". This allows you to provide sane defaults.
+
+	d) Hardware or infrastructure that everybody expects, such as CONFIG_NET
+	   or CONFIG_BLOCK. These are rare exceptions.
+
 - type definition + default value:
 	"def_bool"/"def_tristate" <expr> ["if" <expr>]
   This is a shorthand notation for a type definition plus a value.
-- 
2.9.4

[PATCH 2/2] Documentation/process: Add CONFIG default value to submit-checklist

[Darren Hart]

From: "Darren Hart (VMware)" <dvhart@infradead.org>

Add default value review to the submit checklist, referring to the
preference for "default n" from the previous patch added to
Documentation/kbuild/kconfig-language.txt.

Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <mmarek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
---
 Documentation/process/submit-checklist.rst | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/process/submit-checklist.rst b/Documentation/process/submit-checklist.rst
index a0d9d34..7d04ab3 100644
--- a/Documentation/process/submit-checklist.rst
+++ b/Documentation/process/submit-checklist.rst
@@ -37,7 +37,9 @@ and elsewhere regarding submitting Linux kernel patches.
    You should be able to justify all violations that remain in
    your patch.
 
-6) Any new or modified ``CONFIG`` options don't muck up the config menu.
+6) Any new or modified ``CONFIG`` options do not muck up the config menu and
+  default to off unless they meet the exception criteria documented in
+  ``Documentation/kbuild/kconfig-language.txt`` Menu attributes: default value.
 
 7) All new ``Kconfig`` options have help text.
 
-- 
2.9.4

Re: [PATCH 0/2] Documentation: Add guidance on CONFIG default value

[Jonathan Corbet]

On Mon, 20 Nov 2017 14:39:32 -0800
Darren Hart <dvhart@infradead.org> wrote:

> Document the preference for "default n" in kconfig-language.txt, and reference
> that in the submit-checklist.rst.

I've (finally) applied the pair to the docs tree, thanks.

jon