Dissecting Interrupts and Browsing DMA

This is the fourth in a series of articles about writing character device drivers as loadable kernel modules. This month, we further investigate the field of interrupt handling. Though it is conceptually simple, practical limitations and constraints make this an “interesting” part of device friver writing, and several different facilities have been provided for different situations. We also invest
Deeper and Further

If you want to go deeper with the topics just described, the best teacher is the source, as usual. Split-half interrupt handlers and task queues are used throughout the mainstream kernel, while the DMA implementation shown here is taken from our ceddrv-0.17, available by ftp from tsx-11.mit.edu.

The next installment will come back to more concrete issues—we realize that both DMA and task queues may appear to be rather esoteric topics. We'll show how mmap() works and how a driver may implement its semantics.

Alessandro Rubini is a 27-year-old Linuxer with a taste for the practical side of computer science and a tendency to delay sleeping. This helps him meet deadlines by exploiting time-zone offsets.

Georg V. Zezschwitz is also 27-year-old Linuxer with the same taste for the practical side of computer science and a tendency to delay sleeping.

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