linux-kernel - Re: [RFC 1/2] printk: Add kernel parameter: mute

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Date:   Thu, 22 Oct 2020 15:16:19 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Shreyas Joshi <shreyas.joshi@...mp.com>,
        shreyasjoshi15@...il.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: Re: [RFC 1/2] printk: Add kernel parameter: mute_console

On 2020-10-22, Petr Mladek <pmladek@...e.com> wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 02d4adbf98d2..52b9e7f5468d 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2974,6 +2974,12 @@
>  			Used for mtrr cleanup. It is spare mtrr entries number.
>  			Set to 2 or more if your graphical card needs more.
>  
> +	mute_console	[KNL]
> +			Completely disable printing of kernel messages to
> +			the console. It can still be used as stdin, stdout,
> +			and stderr for the init process. Also it can be used
> +			for login.

IMHO it would make more sense for this to be a console option:

    console=ttyS0,115200,mute

Then other consoles could still exist that are not muted.

On a side note, I am considering proposing something similar for my
printk-rework efforts. Once console printers are moved to kthreads, some
users may not care about latencies and instead prefer synchronous
printing. My idea for this is to provide a "sync" option for the
console:

    console=ttyS0,115200,sync

John Ogness