I’m troubleshooting a fn-key brightness control problem on my laptop, so I’m wading through a lot of config options in /etc/default/grub, as you can imagine. However, it’s raised a question for me:
What’s the difference between the lines marked
For example, does
behave any differently than
As an unrelated question, what do any of them have to do with mapping the use of my fn keys? The brightness is already adjustable in System Settings due to some
xorg.conf.d/ magic. I just wanna make the keys work.
Here is Solutions:
We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.
The difference in short black’n’white text:
GRUB_CMDLINE_LINUXare always effective.
GRUB_CMDLINE_LINUX_DEFAULTare effective ONLY during normal
boot (NOT during recovery mode).
Entries on this line are added to the end of the ‘linux’ command line
(GRUB legacy’s “kernel” line) for both normal and recovery modes. It
is used to pass options to the kernel.
This line imports any entries to the end of the ‘linux’ line (GRUB
legacy’s “kernel” line). The entries are appended to the end of the
normal mode only.
what do any of them have to do with mapping the use of my Fn keys?
In some cases the ACPI BIOS provides the interfaces required to control the backlight through the generic ACPI interface, but the actual methods are not implemented. So the ACPI driver registers with the hardware and prevents any laptop specific drivers from doing so. In those cases it is possible to prevent the ACPI backlight driver from starting by adding the following line to the kernel boot parameters:
Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂