I need to send kernel command line parameter in raspbian os to turn off spectre/meltdown patches. as i know we can do this in other linux distros through "/etc/default/grub" file by changing "GRUB_CMDLINE_LINUX=". but in raspbian os this file did not exist and even "grub-update" command and also "grub-mkconfig" did not installed.
could anyone tell me how i can pass kernel command line parameter in raspbian os?
You should be able to edit /boot/firmware/cmdline.txt with any editor in privilege mode.
sudo nano /boot/firmware/cmdline.txt
This would allow you to send any kernel command. source
However, I think the mitigation isn't built in Raspbian.