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From: Randy Dunlap <rdunlap@infradead.org>
To: Rob Landley <rob@landley.net>, linux-kernel@vger.kernel.org
Subject: Re: Why is CONFIG_VT forced on?
Date: Mon, 30 Dec 2019 18:03:26 -0800	[thread overview]
Message-ID: <8059d1c4-759d-9911-73c7-211f8576e7f2@infradead.org> (raw)
In-Reply-To: <774dfe49-61a0-0144-42b7-c2cbac150687@landley.net>

On 12/30/19 6:04 PM, Rob Landley wrote:
> 
> 
> On 12/30/19 7:45 PM, Rob Landley wrote:
>> On 12/30/19 6:59 PM, Randy Dunlap wrote:
>>> #
>>> # Character devices
>>> #
>>> CONFIG_TTY=y
>>> # CONFIG_VT is not set
>>>
>>> But first you must set/enable EXPERT.  See the bool prompt.
>>
>> Wait, the if doesn't _disable_ the symbol? It disables _editability_ of the
>> symbol, but the symbol can still be on (and displayed) when the if is false?
>> (Why would...)
>>
>> Ok. Thanks for pointing that out. Any idea why the menuconfig help text has no
>> mention of this?
> 
> So if I disable CONFIG_EXPERT, using miniconfig I then need to manually switch on:
> 
> ./init/Kconfig:	bool "Namespaces support" if EXPERT
> ./init/Kconfig:	bool "Multiple users, groups and capabilities support" if EXPERT
> ./init/Kconfig:	bool "Sysfs syscall support" if EXPERT
> ./init/Kconfig:	bool "open by fhandle syscalls" if EXPERT
> ./init/Kconfig:	bool "Posix Clocks & timers" if EXPERT
> ./init/Kconfig:	bool "Enable support for printk" if EXPERT
> ./init/Kconfig:	bool "BUG() support" if EXPERT
> ./init/Kconfig:	bool "Enable ELF core dumps" if EXPERT
> ./init/Kconfig:	bool "Enable full-sized data structures for core" if EXPERT
> ./init/Kconfig:	bool "Enable futex support" if EXPERT
> ./init/Kconfig:	bool "Enable eventpoll support" if EXPERT
> ./init/Kconfig:	bool "Enable signalfd() system call" if EXPERT
> ./init/Kconfig:	bool "Enable timerfd() system call" if EXPERT
> ./init/Kconfig:	bool "Enable eventfd() system call" if EXPERT
> ./init/Kconfig:	bool "Use full shmem filesystem" if EXPERT
> ./init/Kconfig:	bool "Enable AIO support" if EXPERT
> ./init/Kconfig:	bool "Enable IO uring support" if EXPERT
> ./init/Kconfig:	bool "Enable madvise/fadvise syscalls" if EXPERT
> ./init/Kconfig:	bool "Enable membarrier() system call" if EXPERT
> ./init/Kconfig:	bool "Load all symbols for debugging/ksymoops" if EXPERT
> ./init/Kconfig:	bool "Enable rseq() system call" if EXPERT
> ./init/Kconfig:	bool "Enabled debugging of rseq() system call" if EXPERT
> ./init/Kconfig:	bool "PC/104 support" if EXPERT
> ./init/Kconfig:	bool "Enable VM event counters for /proc/vmstat" if EXPERT
> 
> plus of course
> 
> ./arch/x86/Kconfig.cpu:	bool "Supported processor vendors" if EXPERT
> ./arch/x86/Kconfig:	bool "DMA memory allocation support" if EXPERT
> ./arch/x86/Kconfig:	bool "Enable DMI scanning" if EXPERT
> ./arch/x86/Kconfig:	bool "Enable support for 16-bit segments" if EXPERT
> ./arch/x86/Kconfig:       bool "Enable vsyscall emulation" if EXPERT
> ./arch/x86/Kconfig:	bool "Enable the LDT (local descriptor table)" if EXPERT
> ./arch/x86/Kconfig:	bool "Read CNB20LE Host Bridge Windows" if EXPERT
> ./arch/x86/Kconfig:	bool "ISA bus support on modern systems" if EXPERT
> ./arch/x86/Kconfig:	bool "ISA-style DMA support" if (X86_64 && EXPERT)
> 
> So nobody noticed you have a structural "this config option actually switches
> this thing _off_" implemented via magic symbol then?

I guess nobody had a problem with it for the last 10 or 15 or 20 years.

> I think the right fix here involves running sed after kconfig does its thing...

I doubt that would work, but if it does, go for it.

-- 
~Randy


  reply	other threads:[~2019-12-31  2:03 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-31  0:30 Why is CONFIG_VT forced on? Rob Landley
2019-12-31  0:36 ` Randy Dunlap
2019-12-31  0:53   ` Rob Landley
2019-12-31  0:59     ` Randy Dunlap
2019-12-31  1:45       ` Rob Landley
2019-12-31  2:00         ` Randy Dunlap
2019-12-31  2:04         ` Rob Landley
2019-12-31  2:03           ` Randy Dunlap [this message]
2019-12-31  2:33             ` Theodore Y. Ts'o
2019-12-31  2:40           ` Al Viro
2019-12-31  2:52             ` Al Viro
2019-12-31  3:27               ` Rob Landley
2019-12-31  3:53                 ` Al Viro
2019-12-31  4:18                   ` Al Viro
2019-12-31  5:58                     ` Al Viro
2020-01-01 20:41                       ` [PATCH] menuconfig: restore prompt dependencies in help text Arvind Sankar
2020-01-01 21:04                         ` Al Viro
2020-01-01 22:26                           ` Arvind Sankar
2020-01-02 16:14                             ` Randy Dunlap
2020-01-02 23:14                               ` [PATCH] kconfig: " Arvind Sankar
2020-01-03  2:10                                 ` Masahiro Yamada
2020-01-03  4:20                                   ` Arvind Sankar
2019-12-31  1:55 ` Why is CONFIG_VT forced on? Theodore Y. Ts'o
2020-01-04 20:27   ` Enrico Weigelt, metux IT consult
2019-12-31  2:28 ` Al Viro

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