System Calls

System Calls - System Calls System Calls is the way user...

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System Calls System Calls is the way user programs request services from the OS System calls use Software Interrupts Examples of system calls are: open(filename, mode) read(file, buffer, size) write(file, buffer, size) fork() execve(cmd, args); System calls is the API of the OS from the user
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Why do we use Software Interrupts for syscalls instead of function calls? Software Interrupts will switch into kernel mode OS services need to run in kernel mode because: They need privileged instructions Accessing devices and kernel data structures They need to enforce the security in kernel mode.
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Only operations that need to be executed by the OS in kernel mode are part of the system calls. Function like sin(x), cos(x) are not system calls. Some functions like printf(s) run mainly in user mode but eventually call write() when for example the buffer is full and needs to be flushed.
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System Calls - System Calls System Calls is the way user...

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