This setting controls how OS awareness is disabled. It is set to Prompt_on_Unload by default.

Prompt_on_Unload             A prompt dialog is displayed asking which of the following actions you want to take:

Do Nothing
End RSD
End RTOS support

End_on_Disconnect           RTOS awareness is terminated when the connection is terminated.

End_RSD_on_Unload           Running System Debug support is disabled when the image is unloaded. It tries to disconnect from the debug agent and then resets RSD support in RealView Debugger

End_on_Unload                    RTOS support is disabled when the image is unloaded. If Running System Debug is enabled, this option also disables it.