The patch titled Subject: init: handle bootloader identifier in kernel parameters has been added to the -mm mm-nonmm-unstable branch. Its filename is init-handle-bootloader-identifier-in-kernel-parameters.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Huacai Chen chenhuacai@loongson.cn Subject: init: handle bootloader identifier in kernel parameters Date: Mon, 21 Jul 2025 18:13:43 +0800

BootLoader (Grub, LILO, etc) may pass an identifier such as "BOOT_IMAGE= /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= 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=/bin/bash, bootloader identifier can even cause a crash):

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.

Link: https://lkml.kernel.org/r/20250721101343.3283480-1-chenhuacai@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Cc: Al Viro viro@zeniv.linux.org.uk Cc: Christian Brauner brauner@kernel.org Cc: Jan Kara jack@suse.cz Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

init/main.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)

--- a/init/main.c~init-handle-bootloader-identifier-in-kernel-parameters +++ a/init/main.c @@ -544,6 +544,12 @@ static int __init unknown_bootoption(cha const char *unused, void *arg) { size_t len = strlen(param); + /* + * Well-known bootloader identifiers: + * 1. LILO/Grub pass "BOOT_IMAGE=..."; + * 2. kexec/kdump (kexec-tools) pass "kexec". + */ + const char *bootloader[] = { "BOOT_IMAGE=", "kexec", NULL };

/* Handle params aliased to sysctls */ if (sysctl_is_alias(param)) @@ -551,6 +557,12 @@ static int __init unknown_bootoption(cha

repair_env_string(param, val);

+ /* Handle bootloader identifier */ + 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; _

Patches currently in -mm which might be from chenhuacai@loongson.cn are

init-handle-bootloader-identifier-in-kernel-parameters.patch