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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Message-ID: <20161215100931.GJ14217@n2100.armlinux.org.uk>
Date:   Thu, 15 Dec 2016 10:09:32 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Pali Rohár <pali.rohar@...il.com>
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 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.

> 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);
 


-- 
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