pi@k8wk-2:~ $ uname -a Linux k8wk-2 4.19.118-v7l+ #1311 SMP Mon Apr 27 14:26:42 BST 2020 armv7l GNU/Linux
just tried editing the file /boot/firmware/cmdline.txt, does not exist on my raspberry pi 4.
pi@k8wk-2:~ $ uname -a
Linux k8wk-2 4.19.118-v7l+ #1311 SMP Mon Apr 27 14:26:42 BST 2020 armv7l GNU/Linux