linux-kernel - Re: [PATCH 04/23] kconfig: set SYMBOL_AUTO to the symbol marked with defconfig

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Message-ID: <CAK7LNARjgqCbTO7x_8kzzfCdU6HWNyFLNZzwfU2hYRZmWHT_kw@mail.gmail.com>
Date:   Fri, 2 Mar 2018 00:05:18 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Ulf Magnusson <ulfalizer@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 04/23] kconfig: set SYMBOL_AUTO to the symbol marked with defconfig_list

2018-02-17 3:38 GMT+09:00 Masahiro Yamada <yamada.masahiro@...ionext.com>:
> The 'defconfig_list' is a weird attribute.  If the '.config' is
> missing, conf_read_simple() iterates over all visible defaults,
> then it uses the first one for which fopen() succeeds.
>
> config DEFCONFIG_LIST
>         string
>         depends on !UML
>         option defconfig_list
>         default "/lib/modules/$UNAME_RELEASE/.config"
>         default "/etc/kernel-config"
>         default "/boot/config-$UNAME_RELEASE"
>         default "$ARCH_DEFCONFIG"
>         default "arch/$ARCH/defconfig"
>
> However, like other symbols, the first visible default is always
> written out to the .config file.  This might be different from what
> has been actually used.
>
> For example, on my machine, the third one "/boot/config-$UNAME_RELEASE"
> is opened, like follows:
>
>   $ rm .config
>   $ make oldconfig 2>/dev/null
>   scripts/kconfig/conf  --oldconfig Kconfig
>   #
>   # using defaults found in /boot/config-4.4.0-112-generic
>   #
>   *
>   * Restart config...
>   *
>   *
>   * IRQ subsystem
>   *
>   Expose irq internals in debugfs (GENERIC_IRQ_DEBUGFS) [N/y/?] (NEW)
>
> However, the resulted .config file contains the first one since it is
> visible:
>
>   $ grep CONFIG_DEFCONFIG_LIST .config
>   CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
>
> In order to stop confusing people, prevent this CONFIG option from
> being written to the .config file.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---


This one is almost trivial, so I will pick it up now.

Ulf, do you have any comment about this one?




> I'd like to fix the root case of this weirdness later.
> (and other 'option' attributes as well)
>
> But, this series is focusing a more important work in a bigger picture.
>
> For now, I decided to just hide CONFIG_DEFCONFIG_LIST
> from the .config file.
>
>
>  scripts/kconfig/menu.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 9922285..36cd3e1 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -212,6 +212,7 @@ void menu_add_option(int token, char *arg)
>                         sym_defconfig_list = current_entry->sym;
>                 else if (sym_defconfig_list != current_entry->sym)
>                         zconf_error("trying to redefine defconfig symbol");
> +               sym_defconfig_list->flags |= SYMBOL_AUTO;
>                 break;
>         case T_OPT_ENV:
>                 prop_add_env(arg);
> --
> 2.7.4
>
> --
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-- 
Best Regards
Masahiro Yamada