Wednesday, February 24, 2010

Device Drivers: From LDD3

DEFINITION:
Device drivers are black boxes that make a particular piece of hardware respond to a well defined software interface. This is done using a standard set of system calls. The device driver maps the system calls to device specific operations that act on real hardware.

ROLE:
Software can be split into two parts: (1) Mechanism & (2) Policy
Mechanism - What capabilities are to be provided?
Policy - How those capabilities can be used?
The role of the device driver is providing mechanism, not policy
Note: Write device driver to access the hardware, but don't force particular policies on the user. {"POLICY-FREE DRIVERS"}

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