EFISTUB: If I have both CMDLINE configured in kernel, AND via efibootmgr, which one gets executed / takes precedence?
suppose I enable CONFIG_CMDLINE_BOOL=y and CONFIG_CMDLINE="...", but I also add a cmdline using efibootmgr via -u option, which one takes precedence and gets executed?
Does an initramfs make this more complicated? does it also have its own cmdline?
In arch/x86/Kconfig of the kernel tree it says for CMDLINE:
Enter arguments here that should be compiled into the kernel
image and used at boot time. If the boot loader provides a
command line at boot time, it is appended to this string to
form the full kernel command line, when the system boots.
However, you can use the CONFIG_CMDLINE_OVERRIDE option to
change this behavior.
In most cases, the command line (whether built-in or provided
by the boot loader) should specify the device for the root
file system.
and for CMDLINE_OVERRIDE:
Set this option to 'Y' to have the kernel ignore the boot loader
command line, and use ONLY the built-in command line.
This is used to work around broken boot loaders. This should
be set to 'N' under normal conditions.
So both commandlines will probably be used. I don't think an initramfs will normally interfere with the kernel commandline. In any case you can make sure you got what you wanted with cat /proc/cmdline.
ok idk what that all was. Here's something more interesting:
In arch/x86/kernel/setup.c it says /* append boot loader cmdline to builtin */. I think that suggests that the builtin comes first. And I assume that the code that queries the command line scans left to
right and selects the first instance of an option because there doesn't seem to be anywhere that "loads" args into some kind of structure.