open source - What parts of Linux kernel can I read for fun?

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(Closed). This question is opinion-based. It is not currently accepting answers. question from:https://stackoverflow.com/questions/1010724/what-parts-of-linux-kernel-can-i-read-for-fun

Answer 1

I would recommend looking at LXR. It makes it easier to follow the flow of the code (you do not have to search for each function that is called — well, you have, but the site does it for you).

Some starting points, for the current version (2.6.30):

• start_kernel() — think of it as the kernel equivalent of main(). This function initializes almost all the kernel subsystems; follow it to see in code what you see scrolling on the screen during the boot.
• entry_32.S — system calls and interrupts (x86-32 version, which should be nearer what you know; note the use of the AT&T assembly dialect instead of the Intel dialect you might be more used to).
• head_32.S — the kernel entry point. This is where the kernel starts after switching to protected mode; in the end, it will call start_kernel().
• arch/x86/boot — the real-mode bootstrap code. It starts in assembly (boot/header.S), but quickly jumps into C code (starting at boot/main.c). Does the real-mode initialization (mostly BIOS calls which have to be done before switching to protected mode); it is compiled using a weird GCC trick (.code16gcc), which allows the generation of 32-bit real-mode code.
• arch/x86/boot/compressed — if you ever wondered where does the "Decompressing Linux..." message comes from, it is from here.