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Subject: Re: Why is CONFIG_VT forced on?
To:     Rob Landley <rob@landley.net>, linux-kernel@vger.kernel.org
References: <9b79fb95-f20c-f299-f568-0ffb60305f04@landley.net>
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 <ac0e5b3b-6e70-6ab0-0c7f-43175b73058f@landley.net>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <e55624fa-7112-1733-8ddd-032b134da737@infradead.org>
Date:   Mon, 30 Dec 2019 16:59:45 -0800
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On 12/30/19 4:53 PM, Rob Landley wrote:
> 
> 
> 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).


#
# Character devices
#
CONFIG_TTY=y
# CONFIG_VT is not set

But first you must set/enable EXPERT.  See the bool prompt.


-- 
~Randy