Final Exam CMSC 421(All solved)

What is a system call? correct answers Programming interface to the services provided by the OS kernel. request to the operating system to allow user to wait for I/O completion What is a kernel module? correct answers a piece of code that can be added to the kernel at runtime to extend its functionality. What is the /dev file system correct answers Where the device driver files are held. In project 3 our kernel module was . We accessed the file by saying /dev/chess What is the difference between system calls and kernel modules? correct answers system calls provide a communication interface between user-level processes and the kernel, allowing them to request services from the operating system. On the other hand, kernel modules extend the functionality of the kernel itself, enabling the addition of new features, drivers, or system capabilities without modifying the core kernel code. System calls execute in userspace, kernel modules execute in kernel mode. System calls invoked in userspace programs, kernel modules not directly invoked and dynamically inserted at start of program or when needed. System calls allow userspace programs to access certain kernel features through their calls. Kernel modules have direct access to hardware and pieces of the kernel. Character Device correct answers A device that transmits or receives information as streams of characters, one character at a time. An example is a keyboard. Block devices correct answers Block devices transfer data in fixed-size blocks or chunks. Block devices are commonly used for random access storage devices like hard drives, SSDs, and USB drives. Differences between character and block devices correct answers Character devices access information as a stream of characters. Block devices access information in blocks. Character devices process information as a stream of characters with no order. Block devices process information in blocks. Character devices are relatively slow where block devices tend to be faster. Character Devices are used for things that dont require a file system like terminals, serial ports, audio devices, etc. Block devices used for things that need file systems like hard drives, SSDs, USB Drives. Site correct answers a "site" in networking can refer to a physical location, a logical grouping of network resources, or a connection between multiple locations.