First issue is your terminology is all over the place, so others probably can't understand what you are asking about..
Marlin is the firmware. It is just structured text. ie code.
Ardunio IDE (integrated design environment) , this is a text editor and programs that converts the code into binary and upload the binary into the controller.
Tools | ports is part of the Arduino IDE, not Marlin.
Since you say this is grayed out your controllers serial port is not being seen by your operating system.
The MKS_GEN_L controllers have a CH340 chip that does the usb/serial conversion. Most operating systems need drivers installed to talk to this chip.
Drivers for windows and mac os can be found here [
sparks.gogo.co.nz]
Install these and see if anything changes.
Edited 2 time(s). Last edit at 02/19/2019 11:43PM by Dust.