Kernel vs User Space

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The fundamental privilege separation in operating systems. Kernel space has full hardware access and runs OS code; user space runs application code with restricted privileges. System calls are the interface between them, requiring a mode switch that has measurable overhead.

Key Properties

• Privilege Levels
• System Calls
• Mode Switching

Related

• Virtual Memory (enforces the kernel/user boundary)
• eBPF (safely runs user code in kernel space)

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operating-systems memory security