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a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752232018; bh=Kl2wwYKdxu5dO7rsNvg4pv2nYckocqnXAX9CLaLs6Xc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eZxvBjHGhFTzXeoSzMjD1PFRDXjcTK9NUUhOyjVHlneK0KUhnJeUZC0OlIe1lfnfT 9tQldjor/7tGlCBaBbCHRYvg+xkQHDLp2v8RiTUGlyjo7QMq9u86hYOu3RdWe3kCJM loQgC/oBAdSsejOshLkTVdB11kLQ3T0pdqVrdzZg= Date: Fri, 11 Jul 2025 13:06:55 +0200 From: Greg KH To: Huacai Chen Cc: Huacai Chen , Andrew Morton , linux-mm@kvack.org, Alexander Viro , Christian Brauner , Jan Kara , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] init: Handle bootloader head in kernel parameters Message-ID: <2025071130-mangle-ramrod-38ff@gregkh> References: <20250711102455.3673865-1-chenhuacai@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250711102455.3673865-1-chenhuacai@loongson.cn> X-Rspamd-Queue-Id: D4532160010 X-Stat-Signature: f15gz9er6mq9k9ftf53mryrmed7ssqgc X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1752232019-553141 X-HE-Meta: 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 Eq5J1mEJ SFAXSNA59xA/mqF+4wV+VnNzkrWqpRt1HpbF2OdxiojLv8PokFDbe7QPvmi4yB5VgYMSl6XEO4f2OudmLotAvhLtbwJFEDyLF9Yw/ou9aUACcKi8pl4ikZYEORUH24WWcD/Y9sFohQf95GsM8rDxlLw95EkcRife40bL41eqG7/xpQNhtbeNRRgp76+CRVihXXwuA4DFAiBeOo6HB/vXtpAJOzw5bxPLf3T9giMj67gGpMS665OR52/f2S+WHnEBlox45crEvuBPr5vp1ugjKcVeM29hkh8dI248av1Yu3qzFHT/US+bEkHWh0fDsa7GFIgL3V5WkGJEoOUOUki9+gS42zA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 11, 2025 at 06:24:55PM +0800, Huacai Chen wrote: > 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. Then why is it on the kernel command line if it is not recognized? > KEXEC may also pass a head such as "kexec" on some architectures. That's fine, kexec needs this. > 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. Why is this a problem? Don't put stuff that is not needed on the kernel command line :) > > Cc: stable@vger.kernel.org > Signed-off-by: Huacai Chen > --- > 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 }; You need to document why these are ok to "swallow" and not warn for. > > /* 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 */ Handle it how? confused, greg k-h