Kernel and device drivers

• Many device drivers are not implemented directly as character drivers

• They are implemented under a « framework », specific to a given device type (framebuffer, V4L, serial, etc.)

• The framework allows to factorize the common parts of drivers for the same type of devices
• From userspace, they are still seen as character devices by the applications
• The framework allows to provide a coherent userspace interface (ioctl, etc.) for every type of device, regardless of the driver

• The device drivers rely on the « bus infrastructure » to enumerate the devices and communicate with them.