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The Kernel Boot Process
The previous post explained how computers boot up right up to the point where the boot loader, after stuffing the kernel image into memory, is about to jump into the kernel entry point. This last post...
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Memory Translation and Segmentation
This post is the first in a series about memory and protection in Intel-compatible (x86) computers, going further down the path of how kernels work. As in the boot series, I’ll link to Linux kernel...
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CPU Rings, Privilege, and Protection
You probably know intuitively that applications have limited powers in Intel x86 computers and that only operating system code can perform certain tasks, but do you know how this really works? This...
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What Your Computer Does While You Wait
This post takes a look at the speed – latency and throughput – of various subsystems in a modern commodity PC, an Intel Core 2 Duo at 3.0GHz. I hope to give a feel for the relative speed of each...
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Cache: a place for concealment and safekeeping
This post shows briefly how CPU caches are organized in modern Intel processors. Cache discussions often lack concrete examples, obfuscating the simple concepts involved. Or maybe my pretty little head...
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Getting Physical With Memory
When trying to understand complex systems, you can often learn a lot by stripping away abstractions and looking at their lowest levels. In that spirit we take a look at memory and I/O ports in their...
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Anatomy of a Program in Memory
Memory management is the heart of operating systems; it is crucial for both programming and system administration. In the next few posts I’ll cover memory with an eye towards practical aspects, but...
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How The Kernel Manages Your Memory
After examining the virtual address layout of a process, we turn to the kernel and its mechanisms for managing user memory. Here is gonzo again: Linux processes are implemented in the kernel as...
View ArticleThe Thing King
I hope the previous post explained virtual memory adequately, but I must admit I held back a much better explanation, which I first saw in Expert C Programming. It wasn’t written by the book’s author,...
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Page Cache, the Affair Between Memory and Files
Previously we looked at how the kernel manages virtual memory for a user process, but files and I/O were left out. This post covers the important and often misunderstood relationship between files and...
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