Re: Re: [PATCH] ARM: Fix support for CMDLINE_EXTEND

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Mon, Mar 31, 2025 at 08:29:21AM +0000, 谢致邦 (XIE Zhibang) wrote:
> > Later arguments override earlier arguments. Any compiled-in command line
> > needs to be overridable by user supplied input from the boot loader. The
> > current behaviour is correct.
> 
> CMDLINE_EXTEND is for the built-in command line to "Extend bootloader kernel
> arguments", not for the bootloader command line to extend/override built-in
> command line.
> 
> Don't forget that the default empty CMDLINE already gives the bootloader the
> ability to override everything. Not to mention that even if CMDLINE is not
> empty, the default CMDLINE_FROM_BOOTLOADER continues to give the bootloader the
> ability to override all.

The help text:

+         The command-line arguments provided by the boot loader will be
+         appended to the default kernel command string.

so, you end up with default kernel command string _followed by_ the
boot loader arguments. This allows the boot loader arguments to
override anything that is in the default kernel command string.
That's why it is a _default_ - it can be overrided.

If the boot loader command string is extended by the default kernel
command string, then that doesn't happen.

CMDLINE_EXTEND is default _followed by_ boot loader.

You're wanting it to be the other way around. That's broken.

No.

Sorry.

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