Jean-Paul Rustom :
I was studying system calls from my operating systems course until this image appeared and I couldn't exactly understand its content. Can anyone explain to me what is going on in user space and kernel space?
zig razor :
I try to Explain the mechanism of a system call to answer to your question:
When a System call is invoked a software interrupt is raised in user space ( or better in user mode ).
At this point, ever in user mode, the state of the user program is saved into memory.
- After that there is the transaction in the kernel mode ( or kernel space ) to handle the interrupt, and return the value to the user space.
- Then ,in user mode, the state of the running user program is restored from memory and the execution goes ahead.
I leave you a complete description of system call in this link : Kernel System Call