Re: kbuild: default n removals?

Path	csiph.com!weretis.net!feeder4.news.weretis.net!news.mixmin.net!aioe.org!gothmog.csi.it!bofh.it!news.nic.it!robomod
From	Michal Marek <mmarek@suse.com>
Newsgroups	linux.kernel
Subject	Re: kbuild: default n removals?
Date	Wed, 15 Jun 2016 12:10:01 +0200
Message-ID	<rKfVL-1co-11@gated-at.bofh.it> (permalink)
References	<rHt8S-5BX-25@gated-at.bofh.it> <rHtix-5Fq-3@gated-at.bofh.it> <rHx2N-82s-3@gated-at.bofh.it> <rHLSa-LR-37@gated-at.bofh.it> <rHMbv-ST-3@gated-at.bofh.it> <rHNqW-1PK-29@gated-at.bofh.it> <rHNKi-1Yh-27@gated-at.bofh.it>
X-Original-To	Joe Perches <joe@perches.com>
User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0
MIME-Version	1.0
Content-Type	text/plain; charset=windows-1252
Content-Transfer-Encoding	7bit
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	55
Organization	linux.* mail to news gateway
X-Original-Cc	Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>, Guenter Roeck <linux@roeck-us.net>, Wim Van Sebroeck <wim@iguana.be>, Wolfram Sang <wsa@the-dreams.de>, Robin Gong <b38343@freescale.com>, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kbuild <linux-kbuild@vger.kernel.org>
X-Original-Date	Wed, 15 Jun 2016 12:02:36 +0200
X-Original-Message-ID	<576127BC.6050905@suse.com>
X-Original-References	<1465321127-19522-1-git-send-email-vladimir_zapolskiy@mentor.com> <1465321127-19522-5-git-send-email-vladimir_zapolskiy@mentor.com> <20160607214309.GA17129@roeck-us.net> <57581FB2.10806@mentor.com> <57582363.8050406@roeck-us.net> <5758358A.602@mentor.com> <1465400332.25087.56.camel@perches.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1422854

Show key headers only | View raw

On 2016-06-08 17:38, Joe Perches wrote:
> (Adding Michal Marek and linux-kbuild)
> 
> On Wed, 2016-06-08 at 18:11 +0300, Vladimir Zapolskiy wrote:
>> On 08.06.2016 16:53, Guenter Roeck wrote:
>>> On 06/08/2016 06:37 AM, Vladimir Zapolskiy wrote:
>>>>>> +comment "Watchdog Pretimeout Governors"
>>>>>> +
>>>>>> +config WATCHDOG_PRETIMEOUT_GOV
>>>>>> +	bool "Enable watchdog pretimeout governors"
>>>>>> +	default n
>>>>> I don't think 'default n" is needed.
>>>>>
>>>> No strict objections, but probably 'default n' may save quite many
>>>> lines in defconfigs.
>>>>
>>> I always wondered why it would be necessary to say "default n".
>>> What is the difference between "default n" and no explicit default ?
>>>
>> I pointed out that it may have impact on defconfig, but experimentally
>> it has no effect.
>>
>> Users of "make oldconfig" get a prompt in both cases as well.
>>
>> Also I haven't found any difference for silentoldconfig, olddefconfig
>> and alldefconfig, I assume explicit "default n" and "def_bool n"
>> can be safely dropped.

Yes, 'default n' is a noop.


> It's not completely clear removals are always appropriate.
> 
> from: Documentation/kbuild/kconfig-language.txt:
> ------------------------------------------------------------------
> - default value: "default" <expr> ["if" <expr>]
>   A config option can have any number of default values. If multiple
>   default values are visible, only the first defined one is active.
>   Default values are not limited to the menu entry where they are
>   defined. This means the default can be defined somewhere else or be
>   overridden by an earlier definition.
>   The default value is only assigned to the config symbol if no other
>   value was set by the user (via the input prompt above). If an input
>   prompt is visible the default value is presented to the user and can
>   be overridden by him.
>   Optionally, dependencies only for this default value can be added with
>   "if".
> ------------------------------------------------------------------
> 
> Michal?  Do you have an opinion or clarification?

As Guenter explained, there can be multiple default statements with
different if conditions. The first statement to match applies.

Michal

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

Re: kbuild: default n removals? Michal Marek <mmarek@suse.com> - 2016-06-15 12:10 +0200

csiph-web