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From: Alper Nebi Yasak <alpernebiyasak@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>, Petr Mladek <pmladek@suse.com>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Biggers <ebiggers@google.com>,
	Feng Tang <feng.tang@intel.com>,
	Grzegorz Halat <ghalat@redhat.com>,
	Lukas Wunner <lukas@wunner.de>, Nicolas Pitre <nico@fluxnic.net>,
	Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [RFC PATCH v2 0/3] Prefer working VT console over SPCR and device-tree chosen stdout-path
Date: Fri, 1 May 2020 18:07:10 +0300	[thread overview]
Message-ID: <3cd630dd-9bb9-e975-7466-c3125aa6afa3@gmail.com> (raw)
In-Reply-To: <CAHp75VeZRwUp+CpOct4dCAQAfyJZBAY7=qSKwRQh935KEMWw+g@mail.gmail.com>



On 01/05/2020 16:16, Andy Shevchenko wrote:
> On Fri, May 1, 2020 at 2:11 PM Alper Nebi Yasak
> <alpernebiyasak@gmail.com> wrote:
>> I'm assuming "by default" here means "without console arguments"
>> regardless of firmware requests. This paragraph (with small changes) is
>> repeated on many other Kconfig descriptions (drivers/tty/serial/Kconfig,
>> drivers/tty/serial/8250/Kconfig, arch/sparc/Kconfig from grepping for
>> '/dev/tty0' on **/Kconfig).
>>
>>  From Documentation/admin-guide/serial-console.rst:
>>
>>> You can specify multiple console= options on the kernel command line.
>>> [...]
>>> Note that you can only define one console per device type (serial, video).
>>>
>>> If no console device is specified, the first device found capable of
>>> acting as a system console will be used. At this time, the system
>>> first looks for a VGA card and then for a serial port. So if you don't
>>> have a VGA card in your system the first serial port will automatically
>>> become the console.
>>
>> and later on:
>>
>>> Note that if you boot without a ``console=`` option (or with
>>> ``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``.
>>> In that case everything will still work.
> 
> I'm wondering if behaviour is changed if you put console=tty1 instead
> of console=tty0.

Just tested again with the QEMU aarch64 VM. Comparing console=tty1 and
console=tty0 cases: /proc/consoles has tty1 instead of tty0 (both also
has ttyAMA0), and `echo '/dev/console is here' >>/dev/console` goes to
vt1 instead of the currently visible vt. Same difference before and
after this patchset.

  reply	other threads:[~2020-05-01 15:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-30 16:14 Alper Nebi Yasak
2020-04-30 16:14 ` [RFC PATCH v2 1/3] printk: Add function to set console to preferred console's driver Alper Nebi Yasak
2020-04-30 16:46   ` Andy Shevchenko
2020-05-01  1:44   ` Sergey Senozhatsky
2020-05-01 11:48     ` Alper Nebi Yasak
2020-05-13  5:35   ` Sergey Senozhatsky
2020-05-24 10:01     ` Daniel Vetter
2020-04-30 16:14 ` [RFC PATCH v2 2/3] vt: Set as preferred console when a non-dummy backend is bound Alper Nebi Yasak
2020-04-30 16:14 ` [RFC PATCH v2 3/3] printk: Preset tty0 as a pseudo-preferred console Alper Nebi Yasak
2020-04-30 16:44 ` [RFC PATCH v2 0/3] Prefer working VT console over SPCR and device-tree chosen stdout-path Andy Shevchenko
2020-04-30 19:32   ` Alper Nebi Yasak
2020-05-01  1:30 ` Sergey Senozhatsky
2020-05-01 11:08   ` Alper Nebi Yasak
2020-05-01 13:16     ` Andy Shevchenko
2020-05-01 15:07       ` Alper Nebi Yasak [this message]
2020-05-13 14:37 ` Petr Mladek
2020-05-13 22:22   ` Benjamin Herrenschmidt
2020-05-15 19:27   ` Alper Nebi Yasak
2020-05-25 13:04     ` Petr Mladek

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