Respuesta :
The main challenge an operating system faces is keeping the operating system within the secured or fixed time limit of a real-time system. If the system doesn't finish a task within a certain give time frame, this may create an issue in the entire system it is running. Hence, when writing an operating system intended for a real-time system, the writer have to be certain that his scheduling tactics don't let response time to exceed the time constraint.
The main challenges facing by operating system between user mode and kernel mode are as follows:
- The size of each parameter which is passing to make system calls must not exceed to the size of registers.
- The parameters should not be more than six.
To deal with the above problem, the parameters are written in the registers before executing system call.
Further explanation:
User Mode: In this mode, CPU has limited access to manage the memory and also access of peripheral devices (network cards and disks) is not permissible. The CPU can be taking away from a program at any tie.
Kernel Mode: The CPU has ability to manage the memory and have access of peripheral devices. The CPU can switch from one program to other program in this mode.
Hence, if program is running in user mode then it prevents to access the other programs.
Switching from User to Kernel Mode: First, set the values with parameters in the registers and execute the trap instruction. Just after that, CPU switches to kernel mode and jumps to the memory location. These instructions are known as system call handler or trap which reads the instructions and perform in kernel mode. After the system call, OS resets the mode to user mode and hence now it can now perform both simultaneously.
Learn more:
1. How does coding work on computers? brainly.com/question/2257971
2. Prediction accuracy of a neural network depends on _______________ and ______________. brainly.com/question/10599832
Answer details:
Grade: College Engineering
Subject: Computer Science
Chapter: Operating System
Keyword:
Computer, CPU, Operating System, user mode, kernel mode, peripheral devices, disks, network cards, trap, instructions, registers, switch, system call, size, handler, parameters, reset
