linux-kernel - Re: [PATCH] init/main.c: Wrap long kernel cmdline when printing to logs

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Message-Id: <20251020115132.10897a599c8fbda4829b3f89@linux-foundation.org>
Date: Mon, 20 Oct 2025 11:51:32 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Douglas Anderson <dianders@...omium.org>
Cc: linux-kernel@...r.kernel.org, Andrew Chant <achant@...gle.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Brian Gerst
 <brgerst@...il.com>, Christian Brauner <brauner@...nel.org>, Francesco
 Valla <francesco@...la.it>, Geert Uytterhoeven <geert+renesas@...der.be>,
 Guo Weikang <guoweikang.kernel@...il.com>, Huacai Chen
 <chenhuacai@...nel.org>, Jan Hendrik Farr <kernel@...rr.cc>, Jeff Xu
 <jeffxu@...omium.org>, Kees Cook <kees@...nel.org>, Masahiro Yamada
 <masahiroy@...nel.org>, Michal Koutný
 <mkoutny@...e.com>, Miguel Ojeda <ojeda@...nel.org>,
 "Mike Rapoport (Microsoft)" <rppt@...nel.org>, Nathan Chancellor
 <nathan@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Randy Dunlap
 <rdunlap@...radead.org>, Shakeel Butt <shakeel.butt@...ux.dev>, Tejun Heo
 <tj@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Thomas
 Weißschuh <thomas.weissschuh@...utronix.de>,
 "Uladzislau Rezki (Sony)" <urezki@...il.com>
Subject: Re: [PATCH] init/main.c: Wrap long kernel cmdline when printing to
 logs

On Sun, 19 Oct 2025 10:06:14 -0700 Douglas Anderson <dianders@...omium.org> wrote:

> The kernel cmdline length is allowed to be longer than what printk can
> handle. When this happens the cmdline that's printed to the kernel
> ring buffer at bootup is cutoff and some kernel cmdline options are
> "hidden" from the logs. This undercuts the usefulness of the log
> message.
> 
> Add wrapping to the printout. 

Do we really need the wrapping?  That will confuse anything which
parses the output expecting a single line.

And the code would presumably be much simpler if we simply chunked up
the printing and spat out one really long line.