Software supplying device-specific operations behind an operating system interface. For these examples its responsibilities include DMA setup and completion handling, or checking status for polled input-output. [ref]
https://pages.cs.wisc.edu/~remzi/OSTEP/file-devices.pdf. Arpaci-Dusseau and Arpaci-Dusseau, OSTEP chapter 36, section 36.7: the driver abstraction
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