linux-kernel - Re: [PATCH] arm: dt: Initialize boot_command_line from CONFIG_CMDLINE in case DT does not provide /chosen/bootargs

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Date:   Fri, 16 Dec 2016 12:42:34 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     "Russell King - ARM Linux" <linux@...linux.org.uk>
Cc:     Arnd Bergmann <arnd@...db.de>, Robin Murphy <robin.murphy@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ben Dooks <ben-linux@...ff.org>,
        Tony Lindgren <tony@...mide.com>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Pavel Machek <pavel@....cz>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm: dt: Initialize boot_command_line from CONFIG_CMDLINE in case DT does not provide /chosen/bootargs

On Thursday 15 December 2016 11:09:32 Russell King - ARM Linux wrote:
> On Thu, Dec 15, 2016 at 01:09:20AM +0100, Pali Rohár wrote:
> > If cmdline is not in DT, but /chosen exists, then function
> > early_init_dt_scan_chosen() use cmdline from CONFIG_CMDLINE.
> 
> Ah, yes.  Looks to me then as if the bug exists there, and not in
> arch code then.  early_init_dt_scan_chosen() completely ignores the
> CMDLINE options if the chosen node is not found.

Yes... but question is: shoud function named early_init_dt_scan_chosen() 
use CONFIG_CMDLINE if there is DT entry? From name dt_scan_chosen I 
would expect that it scan /chosen and set some fields from /chosen...

At least name of that function is confusing.

> > What is reason that CONFIG_CMDLINE is not supported for DT?
> 
> Sorry, that's my mistake - as you've pointed out above, it is
> supported but via generic code.  I was only looking at arch code
> when I made the statement.
> 
> This patch (untested) should solve it:
> 
>  drivers/of/fdt.c | 40 ++++++++++++++++++++--------------------
>  1 file changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index c89d5d231a0e..fb89157332c6 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1073,26 +1073,6 @@ int __init early_init_dt_scan_chosen(unsigned
> long node, const char *uname, if (p != NULL && l > 0)
>  		strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
> 
> -	/*
> -	 * CONFIG_CMDLINE is meant to be a default in case nothing else
> -	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
> -	 * is set in which case we override whatever was found earlier.
> -	 */
> -#ifdef CONFIG_CMDLINE
> -#if defined(CONFIG_CMDLINE_EXTEND)
> -	strlcat(data, " ", COMMAND_LINE_SIZE);
> -	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> -#elif defined(CONFIG_CMDLINE_FORCE)
> -	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> -#else
> -	/* No arguments from boot loader, use kernel's  cmdl*/
> -	if (!((char *)data)[0])
> -		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> -#endif
> -#endif /* CONFIG_CMDLINE */
> -
> -	pr_debug("Command line is: %s\n", (char*)data);
> -
>  	/* break now */
>  	return 1;
>  }
> @@ -1205,6 +1185,26 @@ void __init early_init_dt_scan_nodes(void)
>  	/* Retrieve various information from the /chosen node */
>  	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
> 
> +	/*
> +	 * CONFIG_CMDLINE is meant to be a default in case nothing else
> +	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
> +	 * is set in which case we override whatever was found earlier.
> +	 */
> +#ifdef CONFIG_CMDLINE
> +#if defined(CONFIG_CMDLINE_EXTEND)
> +	strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
> +	strlcat(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +#elif defined(CONFIG_CMDLINE_FORCE)
> +	strlcpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +#else
> +	/* No arguments from boot loader, use kernel's cmdline */
> +	if (!boot_command_line[0])
> +		strlcpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +#endif
> +#endif /* CONFIG_CMDLINE */
> +
> +	pr_debug("Command line is: %s\n", boot_command_line);
> +
>  	/* Initialize {size,address}-cells info */
>  	of_scan_flat_dt(early_init_dt_scan_root, NULL);

Patch is working fine and fixes my problem. You can add my Tested-by.

-- 
Pali Rohár
pali.rohar@...il.com

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