linux-kernel - Re: [PATCH v2 2/2] kconfig: remove 'optional' property support

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Date: Sat, 27 Apr 2024 00:04:44 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Nicolas Schier <n.schier@....de>
Cc: linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker <dalias@...c.org>, 
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>, linux-sh@...r.kernel.org, 
	Jonathan Corbet <corbet@....net>, Nathan Chancellor <nathan@...nel.org>, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] kconfig: remove 'optional' property support

On Wed, Apr 24, 2024 at 9:24 PM Nicolas Schier <n.schier@....de> wrote:
>
> On Tue, Apr 23, 2024 at 01:41:04AM +0900, Masahiro Yamada wrote:
> > The 'choice' statement is primarily used to exclusively select one
> > option, but the 'optional' property allows all entries to be disabled.
> >
> > In the following example, both A and B can be disabled simultaneously:
> >
> >     choice
> >             prompt "choose A, B, or nothing"
> >             optional
> >
> >     config A
> >             bool "A"
> >
> >     config B
> >             bool "B"
> >
> >     endchoice
> >
> > You can achieve the equivalent outcome by other means.
> >
> > A common solution is to add another option to guard the choice block.
> > In the following example, you can set ENABLE_A_B_CHOICE=n to disable
> > the entire choice block:
> >
> >     choice
> >             prompt "choose A or B"
> >             depends on ENABLE_A_B_CHOICE
> >
> >     config A
> >             bool "A"
> >
> >     config B
> >             bool "B"
> >
> >     endchoice
> >
> > Another approach is to insert one more entry as a place-holder:
> >
> >     choice
> >             prompt "choose A, B, or disable both"
> >
> >     config A
> >             bool "A"
> >
> >     config B
> >             bool "B"
> >
> >     config DISABLE_A_AND_B
> >             bool "choose this to disable both A and B"
> >
> >     endchoice
> >
> > Some real examples are DEBUG_INFO_NONE, INITRAMFS_COMPRESSION_NONE,
> > LTO_NONE, etc.
> >
> > The 'optional' property is even more unnecessary for a tristate choice.
> >
> > Without the 'optional' property, you can disable A and B; you can set
> > 'm' in the choice prompt, and disable A and B individually:
> >
> >     choice
> >             prompt "choose one built-in or make them modular"
> >
> >     config A
> >             tristate "A"
> >
> >     config B
> >             tristate "B"
> >
> >     endchoice
> >
> > In conclusion, the 'optional' property was unneeded.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > ---
> >
> > (no changes since v1)
>
> thanks for the patch!
>
> I found just one small remnant that probably should be removed as well:
>
> diff --git a/scripts/kconfig/tests/choice/__init__.py b/scripts/kconfig/tests/choice/__init__.py
> index 4318fce05912f..05e162220085c 100644
> --- a/scripts/kconfig/tests/choice/__init__.py
> +++ b/scripts/kconfig/tests/choice/__init__.py
> @@ -8,4 +8,2 @@ The behavior of 'y' choice is intuitive.  If choice values are tristate,
>  the choice can be 'm' where each value can be enabled independently.
> -Also, if a choice is marked as 'optional', the whole choice can be
> -invisible.
>  """


Thanks. I will fold this.




>
> Reviewed-by: Nicolas Schier <n.schier@....de>
>
> Kind regards,
> Nicolas
>
>
> PS: For other reviewers, this patch (set) depends on
> https://lore.kernel.org/linux-kbuild/20240422161054.2867285-1-masahiroy@kernel.org/



-- 
Best Regards
Masahiro Yamada