Writing Device Drivers

Frame Buffer Specific Configuration Module

When the driver-specific fbconfig() module causes a change in resolution or color depth, that fbconfig() module must send an ioctl to the frame buffer driver. This ioctl triggers the frame buffer driver to call the terminal emulator's mode change callback function with the new screen size and depth. The frame buffer driver and the terminal emulator must agree about the video mode at all times. When the frame buffer driver and the terminal emulator do not agree about the video mode, the information on the screen is illegible and meaningless.