My Raspberry Pi 3B runs fine with the standard installation of ArchLinuxARM-rpi-3-latest.tar.gz. However I cannot set kernel parameters anywhere for a custom TFT. Formerly there was a file cmdline.txt, which doesn't exist here. So where can I set this?
It doesn't run fine, at least right now (March 2019). There is no CPU frequency governor, so your unit is prone to overheating (that's because the arm archlinux
kernel is built to run on multiple devices, not just for the rpi3). What you need to do, apparently, is to install a new
/boot partition and kernel, after the initial install, or you can switch the provided one before the initial install. Check out the
AUR linux-aarch64-raspberrypi-bin package. Then you will have the usual
cmdline.txt and your pi won't burn up. The alternative is to use the
EDIT: After some soul-searching I switched to Raspberry Pi OS 64-bit beta. This alleviates the need to most hacks and saves time.