From nobody Mon Oct 6 13:39:27 2025 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 76BF121D5B3; Mon, 21 Jul 2025 10:14:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753092848; cv=none; b=ZiD/jeBMgh2zXYulUD88H8JtcWKDALrp/JVj77JQkXGz1JP1Lzirvjn3OAtvYy4t2pOsZ0Cxa82ecqNvbn3fw1s+IlcUmSLBBWf0fxmg3Vke7cN5lZ/uczhWAkDKELN189BF2Zbjjl7wFXW/XMGGkjQhZw4P8aIbtusPUOmrgcM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753092848; c=relaxed/simple; bh=nScyJZOEs7kGy1Cy1SeiFA+NP/2JL4BxBNTQORm1M3g=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QfN+C9qx022cEra+Q/wIiNNmcqbmFXdc6p2m3H4FKBwJUB6wcVQc5axsiY3LASHE/Ebcvgd3oPTHsbXxTzaAxDlF2FY7ui6iybyWx6tgRRr0zmE5xSFVqvXhHXd0ZXwVny/7UH1XQTRDq7GhXXZhpYK6l4FVlS5GgxeZEcgZoEE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [223.64.68.193]) by gateway (Coremail) with SMTP id _____8BxYa_qEn5od70uAQ--.55714S3; Mon, 21 Jul 2025 18:14:02 +0800 (CST) Received: from localhost.localdomain (unknown [223.64.68.193]) by front1 (Coremail) with SMTP id qMiowJAxz8PgEn5oAg4gAA--.20199S2; Mon, 21 Jul 2025 18:14:01 +0800 (CST) From: Huacai Chen To: Huacai Chen , Andrew Morton Cc: linux-mm@kvack.org, Alexander Viro , Christian Brauner , Jan Kara , linux-kernel@vger.kernel.org, Huacai Chen , stable@vger.kernel.org Subject: [PATCH V3] init: Handle bootloader identifier in kernel parameters Date: Mon, 21 Jul 2025 18:13:43 +0800 Message-ID: <20250721101343.3283480-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowJAxz8PgEn5oAg4gAA--.20199S2 X-CM-SenderInfo: hfkh0x5xdftxo6or00hjvr0hdfq/ X-Coremail-Antispam: 1Uk129KBj93XoW7tw4fCr1rCFW3GF1xXr17XFc_yoW8KFWUpF WktryfW3ykGws8Cr48Wr4vga4Skwn3Za1UGanxWws8XFn8tFyFqrWrtF1agasxtrWftF42 gFn8ZF18C3ZrCFXCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUU90b4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r106r15M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVWxJr0_GcWln4kS14v26r1Y6r17M2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12 xvs2x26I8E6xACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y 6r17McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64 vIr41l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_ Jrv_JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1V AY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAI cVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42 IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVj vjDU0xZFpf9x07je0PfUUUUU= Content-Type: text/plain; charset="utf-8" BootLoader (Grub, LILO, etc) may pass an identifier such as "BOOT_IMAGE=3D /boot/vmlinuz-x.y.z" to kernel parameters. But these identifiers are not recognized by the kernel itself so will be passed to user space. However user space init program also doesn't recognized it. KEXEC/KDUMP (kexec-tools) may also pass an identifier such as "kexec" on some architectures. We cannot change BootLoader's behavior, because this behavior exists for many years, and there are already user space programs search BOOT_IMAGE=3D in /proc/cmdline to obtain the kernel image locations: https://github.com/linuxdeepin/deepin-ab-recovery/blob/master/util.go (search getBootOptions) https://github.com/linuxdeepin/deepin-ab-recovery/blob/master/main.go (search getKernelReleaseWithBootOption) So the the best way is handle (ignore) it by the kernel itself, which can avoid such boot warnings (if we use something like init=3D/bin/bash, bootloader identifier can even cause a crash): Kernel command line: BOOT_IMAGE=3D(hd0,1)/vmlinuz-6.x root=3D/dev/sda3 ro c= onsole=3Dtty Unknown kernel command line parameters "BOOT_IMAGE=3D(hd0,1)/vmlinuz-6.x", = will be passed to user space. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen --- V2: Update comments and commit messages. V3: Document bootloader identifiers. init/main.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/init/main.c b/init/main.c index 225a58279acd..b25e7da5347a 100644 --- a/init/main.c +++ b/init/main.c @@ -545,6 +545,12 @@ static int __init unknown_bootoption(char *param, char= *val, const char *unused, void *arg) { size_t len =3D strlen(param); + /* + * Well-known bootloader identifiers: + * 1. LILO/Grub pass "BOOT_IMAGE=3D..."; + * 2. kexec/kdump (kexec-tools) pass "kexec". + */ + const char *bootloader[] =3D { "BOOT_IMAGE=3D", "kexec", NULL }; =20 /* Handle params aliased to sysctls */ if (sysctl_is_alias(param)) @@ -552,6 +558,12 @@ static int __init unknown_bootoption(char *param, char= *val, =20 repair_env_string(param, val); =20 + /* Handle bootloader identifier */ + for (int i =3D 0; bootloader[i]; i++) { + if (!strncmp(param, bootloader[i], strlen(bootloader[i]))) + return 0; + } + /* Handle obsolete-style parameters */ if (obsolete_checksetup(param)) return 0; --=20 2.47.3