linux-kernel - [PATCH] init: Handle bootloader head in kernel parameters

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Message-ID: <20250711102455.3673865-1-chenhuacai@loongson.cn>
Date: Fri, 11 Jul 2025 18:24:55 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	linux-kernel@...r.kernel.org,
	Huacai Chen <chenhuacai@...ngson.cn>,
	stable@...r.kernel.org
Subject: [PATCH] init: Handle bootloader head in kernel parameters

BootLoader may pass a head such as "BOOT_IMAGE=/boot/vmlinuz-x.y.z" to
kernel parameters. But this head is not recognized by the kernel so will
be passed to user space. However, user space init program also doesn't
recognized it.

KEXEC may also pass a head such as "kexec" on some architectures.

So the the best way is handle it by the kernel itself, which can avoid
such boot warnings:

Kernel command line: BOOT_IMAGE=(hd0,1)/vmlinuz-6.x root=/dev/sda3 ro console=tty
Unknown kernel command line parameters "BOOT_IMAGE=(hd0,1)/vmlinuz-6.x", will be passed to user space.

Cc: stable@...r.kernel.org
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 init/main.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/init/main.c b/init/main.c
index 225a58279acd..9e0a7e8913c0 100644
--- a/init/main.c
+++ b/init/main.c
@@ -545,6 +545,7 @@ static int __init unknown_bootoption(char *param, char *val,
 				     const char *unused, void *arg)
 {
 	size_t len = strlen(param);
+	const char *bootloader[] = { "BOOT_IMAGE", "kexec", NULL };
 
 	/* Handle params aliased to sysctls */
 	if (sysctl_is_alias(param))
@@ -552,6 +553,12 @@ static int __init unknown_bootoption(char *param, char *val,
 
 	repair_env_string(param, val);
 
+	/* Handle bootloader head */
+	for (int i = 0; bootloader[i]; i++) {
+		if (!strncmp(param, bootloader[i], strlen(bootloader[i])))
+			return 0;
+	}
+
 	/* Handle obsolete-style parameters */
 	if (obsolete_checksetup(param))
 		return 0;
-- 
2.47.1