linux-kernel - Re: [PATCH v3 1/3] printk: Save console options for add_preferred_console

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Message-ID: <ZVzuih3Aw3hdfj2s@smile.fi.intel.com>
Date:   Tue, 21 Nov 2023 19:53:14 +0200
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        "David S . Miller" <davem@...emloft.net>,
        Dhruva Gole <d-gole@...com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v3 1/3] printk: Save console options for
 add_preferred_console_match()

On Tue, Nov 21, 2023 at 01:31:55PM +0200, Tony Lindgren wrote:
> Driver subsystems may need to translate the preferred console name to the
> character device name used. We already do some of this in console_setup()
> with a few hardcoded names, but that does not scale well.
> 
> The console options are parsed early in console_setup(), and the consoles
> are added with __add_preferred_console(). At this point we don't know much
> about the character device names and device drivers getting probed.
> 
> To allow drivers subsystems to set up a preferred console, let's save the
> kernel command line console options. To add a preferred console, let's add
> a new function add_preferred_console_match().
> 
> This allows the serial core layer to support console=DEVNAME:0.0 style
> hardware based addressing in addition to the current console=ttyS0 style
> naming. And we can start moving console_setup() character device parsing
> to the driver subsystem specific code.
> 
> We use a separate array from the console_cmdline array as the character
> device name and index may be unknown at the console_setup() time. And we do
> not want to call __add_preferred_console() until the character device name
> and index are known.
> 
> Adding the console name in addition to the character device name, and a
> flag for an added console, could be added to the struct console_cmdline.
> And the console_cmdline array handling modified accordingly. But that
> complicates things compared saving the console options, and then adding
> the consoles when the subsystems handling the consoles are ready.

...

> +#include <linux/console.h>

> +#include <linux/kernel.h>

I think instead of kernel.h you may want to see these:

linux/init.h
linux/string.h

asm/errno.h

> +#include "console_cmdline.h"

...

> +/**
> + * console_opt_save - Saves kernel command line console option for driver use
> + * @str: Kernel command line console name and option
> + *
> + * Saves a kernel command line console option for driver subsystems to use for
> + * adding a preferred console during init. Called from console_setup() only.

	scripts/kernel-doc -v -none -Wall ...

most likely will complain (no Return section).

> + */
> +int __init console_opt_save(char *str)

str is not const? Hmm...

-- 
With Best Regards,
Andy Shevchenko