From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Peter Hurley <peter@hurleysoftware.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Stefan Agner <stefan@agner.ch>,
linux-serial@vger.kernel.org
Subject: Re: console vs earlycon ?
Date: Thu, 22 Oct 2015 00:54:28 +0200 [thread overview]
Message-ID: <4134303.BAT7dSJRN3@wuerfel> (raw)
In-Reply-To: <5627E679.1050207@hurleysoftware.com>
On Wednesday 21 October 2015 15:24:41 Peter Hurley wrote:
> On 10/21/2015 03:00 PM, Arnd Bergmann wrote:
> > Yes, I see this as a tradeoff: we want the console to be as early as
> > possible in order to report boot-time errors to the user, but not so early
> > to require hacks that can cause problems themselves. earlycon has to
> > do some scary stuff and is relatively recent, while the hacks
> > necessary for console_init() are much older and better tested.
>
> I assume you mean the hacks necessary to get _earlycon_ working at
> console_init() time, because the hacks necessary to get non-8250
> serial consoles working at console_init() would be extensive and
> brand new.
>
No, I was just being slow and assumed that the 51 drivers that come with
a console_initcall() do something in there to actually start the console,
but you are right that most of them don't actually do that. They just
call register_console() and wait for the device to show up later.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: console vs earlycon ?
Date: Thu, 22 Oct 2015 00:54:28 +0200 [thread overview]
Message-ID: <4134303.BAT7dSJRN3@wuerfel> (raw)
In-Reply-To: <5627E679.1050207@hurleysoftware.com>
On Wednesday 21 October 2015 15:24:41 Peter Hurley wrote:
> On 10/21/2015 03:00 PM, Arnd Bergmann wrote:
> > Yes, I see this as a tradeoff: we want the console to be as early as
> > possible in order to report boot-time errors to the user, but not so early
> > to require hacks that can cause problems themselves. earlycon has to
> > do some scary stuff and is relatively recent, while the hacks
> > necessary for console_init() are much older and better tested.
>
> I assume you mean the hacks necessary to get _earlycon_ working at
> console_init() time, because the hacks necessary to get non-8250
> serial consoles working at console_init() would be extensive and
> brand new.
>
No, I was just being slow and assumed that the 51 drivers that come with
a console_initcall() do something in there to actually start the console,
but you are right that most of them don't actually do that. They just
call register_console() and wait for the device to show up later.
Arnd
next prev parent reply other threads:[~2015-10-21 22:54 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-21 8:21 console vs earlycon ? Masahiro Yamada
2015-10-21 8:21 ` Masahiro Yamada
2015-10-21 8:57 ` Arnd Bergmann
2015-10-21 8:57 ` Arnd Bergmann
2015-10-21 9:09 ` Masahiro Yamada
2015-10-21 9:09 ` Masahiro Yamada
2015-10-21 9:19 ` Arnd Bergmann
2015-10-21 9:19 ` Arnd Bergmann
2015-10-21 9:30 ` Masahiro Yamada
2015-10-21 9:30 ` Masahiro Yamada
2015-10-21 10:36 ` Arnd Bergmann
2015-10-21 10:36 ` Arnd Bergmann
2015-10-21 13:53 ` Peter Hurley
2015-10-21 13:53 ` Peter Hurley
2015-10-21 14:13 ` Arnd Bergmann
2015-10-21 14:13 ` Arnd Bergmann
2015-10-21 15:32 ` Peter Hurley
2015-10-21 15:32 ` Peter Hurley
2015-10-21 19:00 ` Arnd Bergmann
2015-10-21 19:00 ` Arnd Bergmann
2015-10-21 19:24 ` Peter Hurley
2015-10-21 19:24 ` Peter Hurley
2015-10-21 22:54 ` Arnd Bergmann [this message]
2015-10-21 22:54 ` Arnd Bergmann
2015-10-21 13:20 ` Peter Hurley
2015-10-21 13:20 ` Peter Hurley
2015-10-22 4:47 ` Masahiro Yamada
2015-10-22 4:47 ` Masahiro Yamada
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