From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Chris Down <chris@chrisdown.name>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Petr Mladek <pmladek@suse.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kernel Team <kernel-team@fb.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>
Subject: Re: [RFC PATCH] printk: console: Allow each console to have its own loglevel
Date: Thu, 19 May 2022 19:48:46 +0200 [thread overview]
Message-ID: <CAMuHMdU5=XW28XBdEx9ofrrysUCqqtoaS7=0U8Mr7TF3XdntWw@mail.gmail.com> (raw)
In-Reply-To: <YoZWFi0AtmA9fvv/@chrisdown.name>
Hi Chris,
CC DT
On Thu, May 19, 2022 at 4:37 PM Chris Down <chris@chrisdown.name> wrote:
> Geert Uytterhoeven writes:
> >All of the above options are appropriate for "classic" systems,
> >where the console device is selected using the "console=" option.
> >
> >On systems using Device tree, the serial console device is selected
> >using the "chosen/stout-path" property in DT, and the graphical
> >console is usually auto-detected and auto-enabled through DRM.
> >Do you envision a way to specify a specific console loglevel on the
> >kernel command line on such systems?
>
> Interesting question! I hadn't really thought about device tree. I actually
> have very little understanding of how it works to be honest :-)
>
> I'm happy to add loglevel support to device tree, I assume I'd add another
> property under the chosen node, like chosen/stdout-loglevel.
Please do not add a new property there.
IMHO, the loglevel should be specified on the kernel command line,
and not be fixed using a DT property.
Typically, boot loaders (e.g. U-Boot) replace the command line
specified in chosen/stdout-path in DT by something retrieved from
the boot environment (e.g. user-specifief bootargs in NVMEM).
> I have some questions, though:
>
> 1. It looks like DT is standardised. Do I need to get standards approval first?
> 2. Is there documentation on how to reliably test DT changes?
The DT specification can be found at
https://www.devicetree.org/specifications/
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2022-05-19 17:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-18 14:24 [RFC PATCH] printk: console: Allow each console to have its own loglevel Chris Down
2022-05-18 14:32 ` Chris Down
2022-05-18 15:34 ` Greg Kroah-Hartman
2022-05-18 19:46 ` Chris Down
2022-05-18 19:54 ` Greg Kroah-Hartman
2022-05-18 20:27 ` Chris Down
2022-05-19 7:04 ` Greg Kroah-Hartman
2022-05-19 14:12 ` Chris Down
2022-05-19 14:35 ` Greg Kroah-Hartman
2022-05-19 15:08 ` Chris Down
2022-05-19 15:24 ` Greg Kroah-Hartman
2022-05-19 15:25 ` Greg Kroah-Hartman
2022-05-19 15:55 ` Chris Down
2022-05-19 17:45 ` Greg Kroah-Hartman
2022-05-19 17:55 ` Chris Down
2022-05-24 9:19 ` Petr Mladek
2022-05-30 10:48 ` [OFFLIST] " Chris Down
2022-05-30 10:49 ` Chris Down
2022-05-19 7:26 ` Geert Uytterhoeven
2022-05-19 14:37 ` Chris Down
2022-05-19 17:48 ` Geert Uytterhoeven [this message]
2022-05-19 18:05 ` Chris Down
2022-05-19 13:59 ` [printk] 6f922c8d53: BUG:kernel_NULL_pointer_dereference,address kernel test robot
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