linux-kernel - Re: Why is CONFIG

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Message-ID: <ac0e5b3b-6e70-6ab0-0c7f-43175b73058f@landley.net>
Date:   Mon, 30 Dec 2019 18:53:44 -0600
From:   Rob Landley <rob@...dley.net>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Subject: Re: Why is CONFIG_VT forced on?

On 12/30/19 6:36 PM, Randy Dunlap wrote:
> On 12/30/19 4:30 PM, Rob Landley wrote:
>> On x86-64 menuconfig, CONFIG_VT is forced on (in drivers->char devices->virtual
>> terminal), but the help doesn't mention a "selects", and I didn't spot anything
>> obvious in "find . -name 'Kconfig*' | xargs grep -rw VT".
>>
>> Congratulations, you've reinvented "come from". I'm mostly familiar with the
>> kconfig plumbing from _before_ you made it turing complete: how do I navigate this?
>>
>> I'm guessing "stick printfs into the menuconfig binary" is the recommended next
>> step for investigating this? Or is there a trick I'm missing?
> 
> I've never had to resort to that trick.
> 
>> Rob
>>
> 
> config VT
> 	bool "Virtual terminal" if EXPERT
> 	depends on !UML
> 	select INPUT
> 	default y
> 	^^^^^^^^^^^^^^^^^^^
> 
> That's all it takes ^^^^^^^^^^^^^^^^.

Try to switch it off. It won't let you, it's forced on by something else. The
help doesn't say what. (That select means it's forcing CONFIG_INPUT on?)

> Does that explain it?  Maybe I don't understand the problem.

It's possible I don't either. I can disable it when when I start from
allnoconfig and then switch CONFIG_TTY on (at which point it defaults to y, but
can be disabled).

Rob