Kernel Modules and Device Drivers

Question 1

What is the File Interface?

Answer 1

An abstraction to organize data into directories and files. Allows for querying data therein.

Question 2

What is the IOCTL device?

Answer 2

Input/Output Control. Allows for users and their applications to communicate with device drivers. Can configure devices or query special files.

Question 3

What is /proc?

Answer 3

A virtual file system that provides access to the kernel internal state. Mostly readonly. Can query statistics or process information in the kernel.

Question 4

What is the difference between a Character Device and a Block Device?

Answer 4

A Character Device is unbuffered, and is accessed sequentially (by necessity). A Block Device provides access to data via a buffer, and can allow for random access.

Question 5

TRUE/FALSE: The mouse is an example of a Character Device.

Answer 5

TRUE.

Question 6

TRUE/FALSE: Terminals are an example of a Character Device.

Answer 6

TRUE.

Question 7

TRUE/FALSE: A random number generator is an example of a Block Device.

Answer 7

FALSE: It is a character device.

Question 8

TRUE/FALSE: A hard drive is an example of a Block Device.

Answer 8

TRUE.

Question 9

What is DMA?

Answer 9

Direct Memory Access. Often hardware-enabled data transfer that avoids the CPU to reduce workload. Faster data transfers, but needs additional coordination with the OS.

Question 10

Name a common use of DMA.

Answer 10

(many answers)
GPU’s, GPGPU’s, TPU’s
HDD’s, SSD’s, CSD’s
Network Interfaces
Sound Cards

Question 11

TRUE/FALSE: DMA only allows for memory-to-memory access.

Answer 11

FALSE: DMA allows for that plus I/O-to-memory and memory-to-I/O.

Question 12

TRUE/FALSE: Interrupts operate exclusively in hardware.

Answer 12

FALSE: Interrupts can also be handled by software.

Question 13

What is the key factor in a GPU’s being better than a CPU in certain cases?

Answer 13

Parallel processing.