linux-kernel - Re: [PATCH v2] init: Don't proxy `console=` to earlycon

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Message-ID: <ZuwfvyiOMAzciZX2@pathway.suse.cz>
Date: Thu, 19 Sep 2024 14:57:35 +0200
From: Petr Mladek <pmladek@...e.com>
To: Raul E Rangel <rrangel@...omium.org>
Cc: linux-kernel@...r.kernel.org, Raul E Rangel <rrangel@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Huang Shijie <shijie@...amperecomputing.com>,
	Ingo Molnar <mingo@...nel.org>, Jiri Slaby <jirislaby@...nel.org>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Yuntao Wang <ytcoode@...il.com>, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2] init: Don't proxy `console=` to earlycon

On Wed 2024-09-11 12:35:14, Raul E Rangel wrote:
> Today we are proxying the `console=` command line args to the
> `param_setup_earlycon()` handler. This is done because the following are
> equivalent:
> 
>     console=uart[8250],mmio,<addr>[,options]
>     earlycon=uart[8250],mmio,<addr>[,options]
> 
> Both invocations enable an early `bootconsole`. `console=uartXXXX` is
> just an alias for `earlycon=uartXXXX`.
> 
> In addition, when `earlycon=` (empty value) or just `earlycon`
> (no value) is specified on the command line, we enable the earlycon
> `bootconsole` specified by the SPCR table or the DT.
> 
> The problem arises when `console=` (empty value) is specified on the
> command line. It's intention is to disable the `console`, but what
> happens instead is that the SPRC/DT console gets enabled.
> 
> This happens because we are proxying the `console=` (empty value)
> parameter to the `earlycon` handler. The `earlycon` handler then sees
> that the parameter value is empty, so it enables the SPCR/DT
> `bootconsole`.
> 
> This change makes it so that the `console` or `console=` parameters no
> longer enable the SPCR/DT `bootconsole`. I also cleans up the hack in
> `main.c` that would forward the `console` parameter to the `earlycon`
> handler.
> 
> Signed-off-by: Raul E Rangel <rrangel@...omium.org>

It like this approach. It works well:

Reviewed-by: Petr Mladek <pmladek@...e.com>
Tested-by: Petr Mladek <pmladek@...e.com>

I could take it via the printk tree for 6.13. From my POV, it is too
late for 6.12. I am sorry I have been busy with the printk rework :-(

I am going to wait few days for another eventual review or taker.

Best Regards,
Petr