Ch.2 Flashcards
Interrupts
Mechanism used by OS to signal the system that a high-priority event has occurred that requires immediate attention.
- I/O drives most interrupts
- Controller places interrupt number in an interrupt register for OS to take action
Interrupt Vector
Data structure for normal technique for handling interrupts
- one entry per interrupt
- each entry contains the address for the interrupt service routine
System Calls
Function call provided by the OS as an interrupt
Switch Steps
1) Change the processor to kernel mode
2) Save and reload the MMU to switch to the kernel address space
3) Save the program counter and reload it with the kernel entry point
I/O Devices
OS includes device drivers that control access to the devices
File Systems
OS module that provides high level interface to allow the user and programs to create, delete, modify, and apply other operations to various types of files
Interrupts
used by OS to signal the system that a high-priority event has occurred that requires immediate attention.
- I/O drives lots of interrupts
- Controller causing the interrupt places interrupt # in an interrupt register. The OS then must take action
Monolithic Kernel
Core functionality such as memory allocation, and scheduling, as well as services such as device drivers and file system exist in the system space
(i.e. Linux)
Microkernel
- Only basic functionality is included in the kernel
- Everything else in user-space
(i.e. Minux)
Program
Sequence of instructions written to perform a specified task
Process
- an instance of a program in execution
Privileged - OS kernel processes which can execute all types of hardware operations and access all memory
User - Can not execute low-level I/O. Memory protection keeps these processes from trashing memory owned by the OS or other processes.
