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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Petr Mladek <pmladek@suse.com>,
	Alper Nebi Yasak <alpernebiyasak@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	linux-serial@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	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: Thu, 14 May 2020 08:22:33 +1000	[thread overview]
Message-ID: <2b67927057455bc91310f88a1952f808339f14cb.camel@kernel.crashing.org> (raw)
In-Reply-To: <20200513143755.GM17734@linux-b0ei>

On Wed, 2020-05-13 at 16:37 +0200, Petr Mladek wrote:
> The only common rules are:
> 
>    + The last console on the command line should always be the
>      preferred one when defined.
> 
>    + Consoles defined by the device (SPCR, device tree) are used
>      when there is no commandline.

With the exception that on x86, SPCR is only used for early_con, we
don't do add_preferred_console() at all for it.

I sort-of understand why... the track record on BIOS quality out there
being what it is, I could see this causing a number of systems start
sending the console to a non-existent or non-wired serial port instead
of the tty/gpu because the BIOS leave SPCR set/enabled for no reason.

It may or may not be the case in practice but I don't see how we can
figure that out without either a large campain of data collection from
tons of systems (which will miss plenty) or just taking the chance &
breaking people and see who screams :-)

Cheers,
Ben.



  reply	other threads:[~2020-05-13 22:24 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
2020-05-13 14:37 ` Petr Mladek
2020-05-13 22:22   ` Benjamin Herrenschmidt [this message]
2020-05-15 19:27   ` Alper Nebi Yasak
2020-05-25 13:04     ` Petr Mladek

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