U-Boot when running on top of EFI (Extensive Firmware Interface).
This is a type of BIOS used by PCs.
+config DEBUG_UART_S5P
+ bool "Samsung S5P"
+ help
+ Select this to enable a debug UART using the serial_s5p driver. You
+ will need to provide parameters to make this work. The driver will
+ be available until the real driver-model serial is running.
+
endchoice
config DEBUG_UART_BASE