Drivers and Switch Tables
The bottom portion of Figure 3-14 shows two switch tables. One is used for accessing block device drivers and the other for raw device drivers. A raw device is one to which data is transferred in byte streams of varying sizes.
A raw device may receive a single byte or many megabytes in a single transfer (or even gigabytes in today's computing climate). Raw device access is also used to talk to and configure device controllers and interface cards when necessary.
Block devices hold mountable file systems. All I/O to a block device is directed through the system's buffer cache to reduce physical requests to logical requests whenever possible for speed and convenience
As drivers are built into the kernel image or registered ...
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