41 lines
1.3 KiB
Markdown
41 lines
1.3 KiB
Markdown
---
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categories:
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- Operating Systems
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- Linux
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tags:
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---
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# Basic model of a \*nix operating system
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We can abstract the Linux OS into three operational levels or tiers, from the bottom up:
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<dl>
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<dt>User processes: user space</dt>
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<dd>The running programs that the kernel manages. Also known as the user space which is the memory that the kernal assigns for user processes. Comprising:
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<ul>
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<li>Graphical user interface</li>
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<li>Servers</li>
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<li>Shell</li>
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</ul>
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<dt>Kernel: kernel space</dt>
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</dd>
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<dd>The core of the operating system. Software residing in memory that tells the CPU where to look for its next task. Acts as a mediator and primary interface between the hardware and the user processes. Known as kernel space: the memory that the kernel allocates for itself. Comprising:
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<ul>
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<li>System calls</li>
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<li>Process management</li>
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<li>Memory management</li>
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<li>Device drivers</li>
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</ul>
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</dd>
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<dt>Hardware</dt>
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<dd>The base: one or more CPUs and RAM memory performing computations and writing to memory. Comprising:
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<ul>
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<li>Processor (CPU)</li>
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<li>Main memory (RAM)</li>
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<li>Disks</li>
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<li>Network ports</li>
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</ul>
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</dl>
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!! Add info on kernel mode and user mode
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https://www.geeksforgeeks.org/user-mode-and-kernel-mode-switching/
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