2 process can intercept the signal and ignore it 3

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: termination. 2. Process can intercept the signal and ignore it. 3. Process can intercept the signal and take a programmer-defined action. We will discuss signals in detail in some of the subsequent lectures. Hardware Protection Multi-programming put several programs in memory at the same time; while this increased system utilizatio n it also increased problems. With sharing, many processes 4 could be adversely affected by a bug in one program. One erroneous program could also modify the program or data of another program or even the resident part of the operating system. A file may overwrite anothe r file or folder on disk. A process may get the CPU and never relinquish it. So the issues of hardware protection are: I/O protection, memory protection, and CPU protection. We will discuss them one by one, but first we talk about the dual- mode operation of a CPU. a) Dual Mode Operation To ensure proper operation, we must protect the operating system and all other programs and their data from any malfunctioning program. Protection is needed for any shared resources. Instruction set of a modern CPU has two kinds of instructions, privileged instructions and non-privileged instructions. Privileged instructions can be used to perform hardware operations that a normal user process should not be able to perform, such as communicating with I/...
View Full Document

Ask a homework question - tutors are online