linux-kernel - Re: [PATCH v2 01/21] lib/vsprintf: Print time and date in human readable format via %pt

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Date:   Wed, 21 Feb 2018 15:19:13 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        Joe Perches <joe@...ches.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        linux-rtc@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Guan Xuetao <gxt@...c.pku.edu.cn>,
        Ingo Molnar <mingo@...nel.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        Jonathan Corbet <corbet@....net>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Thierry Reding <thierry.reding@...il.com>
Subject: Re: [PATCH v2 01/21] lib/vsprintf: Print time and date in human
 readable format via %pt

On Wed, Feb 21, 2018 at 2:23 PM, Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
> On Wed, 2018-02-21 at 08:38 +0100, Rasmus Villemoes wrote:
>> On 2018-02-21 00:55, Joe Perches wrote:
>> > On Tue, 2018-02-20 at 23:43 +0200, Andy Shevchenko wrote:
>> > > There are users which print time and date represented by content
>> > > of
>> > > struct rtc_time in human readable format.
>> > >
>> > > Instead of open coding that each time introduce %ptR[dt][rv]
>> > > specifier.
>> > >
>> > > Note, users have to select PRINTK_PEXT_TIMEDATE option in a
>> > > Kconfig.
>> >
>> > Not sure this is a great option.
>> > Not just the name, the need to select it.
>>
>> Bikeshedding first: If you do keep the config option, please use
>> PRINTF,
>> not PRINTK - vsprintf can be and is used by lots of code other than
>> printk.
>
> OK.
>
>> Well, on the one hand, I like to reduce the size of the kernel when
>> possible and ideally make all new functionality guarded by config
>> options, but OTOH, how much does compiling out the datetime formatters
>> really save?
>
> https://lists.01.org/pipermail/kbuild-all/2017-June/034950.html
>
> I understand that half a year time allows us to increase kernel text
> size by 750+ bytes unconditionally.
>
> I would really like to not use any option.

Agreed.

FTR, growth of my atari_defconfig kernel between v4.7 and v4.15:

add/remove: 351/155 grow/shrink: 691/429 up/down: 63095/-38665 (24430)
add/remove: 394/156 grow/shrink: 595/709 up/down: 61173/-31092 (30081)
add/remove: 1315/711 grow/shrink: 1269/442 up/down: 172871/-92075 (80796)
add/remove: 525/266 grow/shrink: 914/510 up/down: 116115/-46240 (69875)
add/remove: 443/222 grow/shrink: 906/456 up/down: 77807/-40657 (37150)
add/remove: 536/296 grow/shrink: 1043/652 up/down: 97366/-65459 (31907)
add/remove: 413/176 grow/shrink: 711/479 up/down: 75678/-41356 (34322)
add/remove: 311/145 grow/shrink: 898/438 up/down: 51655/-26851 (24804)

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds