From: Peter Hurley <peter@hurleysoftware.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jiri Slaby <jslaby@suse.cz>, Rob Herring <robh@kernel.org>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>
Subject: Re: [PATCH v3 -next 11/11] serial: 8250_early: Remove setup_early_serial8250_console()
Date: Fri, 03 Apr 2015 14:27:30 -0400 [thread overview]
Message-ID: <551EDB92.9070008@hurleysoftware.com> (raw)
In-Reply-To: <CAE9FiQW4PM1aozMOXMfvey2=zVjm3uMVLGW3924eidACBbTjag@mail.gmail.com>
On 04/03/2015 01:44 PM, Yinghai Lu wrote:
> On Fri, Apr 3, 2015 at 10:38 AM, Peter Hurley <peter@hurleysoftware.com> wrote:
>> On 04/03/2015 12:57 PM, Yinghai Lu wrote:
>>
>> Wait -- you have earlycon in a product??
>
> What do you mean?
I mean, what will happen if I put in a big debug banner like Steven
did for ftrace?
Kernel developers need earlycon for debugging arch code; often the earlycon
is just hacked together especially when it requires fixmap support.
Putting it in a product and _relying on undocumented behavior_ is a bad idea.
> when you are using "console=uart8250,io,0x3f8"
> you will have earlycon at first, and handover to console.
which means you have to have CONFIG_SERIAL_EARLYCON to get a serial console
at all.
I have no problem fixing this _if this is causing actual regressions_,
and not simply some minor inconvenience that can be fixed by editing your
grub command line.
However, I see this undocumented behavior as a cautionary tale for why not
every kernel command line hack should be accepted in mainline.
Regards,
Peter Hurley
next prev parent reply other threads:[~2015-04-03 18:27 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-09 20:27 [PATCH v3 -next 00/11] Extensible console matching & direct earlycon Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 01/11] console: Add extensible console matching Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 02/11] serial: core: Fix kernel doc for uart_console_write() Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 03/11] serial: 8250_early: Remove early_device variable Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 04/11] serial: earlycon: Move ->uartclk initialize Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 05/11] serial: 8250_early: Assume uart already initialized if no baud option Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 06/11] serial: 8250_early: Fix setup() error code Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 07/11] serial: earlycon: Ignore parse_options() " Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 08/11] serial: earlycon: Skip parse_options() if empty string Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 09/11] serial: earlycon: Refactor earlycon registration Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 10/11] serial: earlycon: Enable earlycon without command line param Peter Hurley
2015-03-09 20:27 ` [PATCH v3 -next 11/11] serial: 8250_early: Remove setup_early_serial8250_console() Peter Hurley
2015-04-02 2:04 ` Yinghai Lu
2015-04-02 3:22 ` Peter Hurley
2015-04-02 9:15 ` Yinghai Lu
2015-04-02 16:31 ` Peter Hurley
2015-04-02 17:23 ` Yinghai Lu
2015-04-02 22:12 ` Yinghai Lu
2015-04-02 22:36 ` Yinghai Lu
2015-04-03 0:02 ` Yinghai Lu
2015-04-03 0:22 ` Yinghai Lu
2015-04-03 2:38 ` Yinghai Lu
2015-04-03 10:37 ` Peter Hurley
2015-04-03 16:57 ` Yinghai Lu
2015-04-03 17:38 ` Peter Hurley
2015-04-03 17:44 ` Yinghai Lu
2015-04-03 18:27 ` Peter Hurley [this message]
2015-04-03 19:00 ` Greg Kroah-Hartman
2015-04-03 23:03 ` [PATCH] earlycon: 8250: Fix command line regression Peter Hurley
2015-04-04 0:04 ` [PATCH v2] " Peter Hurley
2015-04-04 2:19 ` Yinghai Lu
2015-04-04 2:29 ` Peter Hurley
2015-04-04 2:50 ` Peter Hurley
2015-04-04 3:00 ` Yinghai Lu
2015-04-04 2:56 ` Yinghai Lu
2015-04-04 3:09 ` Peter Hurley
2015-04-04 3:28 ` Yinghai Lu
2015-04-04 3:09 ` Yinghai Lu
2015-04-04 3:15 ` Peter Hurley
2015-04-04 3:24 ` Yinghai Lu
2015-04-04 3:31 ` Yinghai Lu
2015-04-04 3:32 ` Peter Hurley
2015-04-04 3:37 ` Yinghai Lu
2015-04-04 3:41 ` Peter Hurley
2015-04-04 6:05 ` Yinghai Lu
2015-04-04 14:27 ` [PATCH v3] " Peter Hurley
2015-04-04 16:09 ` Greg Kroah-Hartman
2015-04-04 16:23 ` Peter Hurley
2015-04-04 16:52 ` Greg Kroah-Hartman
2015-04-04 17:08 ` Peter Hurley
2015-04-04 17:19 ` [PATCH v4] " Peter Hurley
2015-04-04 17:24 ` Peter Hurley
2015-04-04 17:41 ` Greg Kroah-Hartman
2015-04-05 7:09 ` Yinghai Lu
2015-04-05 13:06 ` Peter Hurley
2015-04-05 20:14 ` Yinghai Lu
2015-04-05 14:52 ` [PATCH v5] " Peter Hurley
2015-04-05 20:02 ` Yinghai Lu
2015-04-06 14:48 ` [PATCH v6] " Peter Hurley
2015-04-04 0:52 ` [PATCH v3 -next 11/11] serial: 8250_early: Remove setup_early_serial8250_console() Yinghai Lu
2015-04-04 1:16 ` Peter Hurley
2015-04-04 1:16 ` Peter Hurley
2015-04-04 0:58 ` Yinghai Lu
2015-03-26 17:13 ` [PATCH v3 -next 00/11] Extensible console matching & direct earlycon Greg Kroah-Hartman
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