UEFI actually lets you provide both touchscreen-capable bells&whistles gui, and a text UI for the frankenstein VT-UTF8 standard (essentially, VT-220 compatible with UTF-8, kinda like linux console) - all in mostly one codebase.
There's a standard UI description language which is used to specify menus, options and values (and how they are written into nvram), which is then interpreted by text mode interface driver (enabled when you connect over serial port) and graphic mode interface driver (where you can drop all sorts of graphical bells & whistles).
It's also how you can integrate menus from add-on cards into firmware setup.
UEFI actually lets you provide both touchscreen-capable bells&whistles gui, and a text UI for the frankenstein VT-UTF8 standard (essentially, VT-220 compatible with UTF-8, kinda like linux console) - all in mostly one codebase.
There's a standard UI description language which is used to specify menus, options and values (and how they are written into nvram), which is then interpreted by text mode interface driver (enabled when you connect over serial port) and graphic mode interface driver (where you can drop all sorts of graphical bells & whistles).
It's also how you can integrate menus from add-on cards into firmware setup.