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Exploring the internals of Linux v0.01

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Summary

This article explores Linux v0.01, which is the earliest version of the Linux kernel. It consists of 10,239 lines of code and has 66 system calls, which supports reading, writing, creating, and deleting files and directories. The article discusses the various features of this version, such as the MINIX file system, the scheduler, the kernel panic, and the fork(2) in kernel space. It also mentions that the kernel was deeply hardcoded for Intel 386 architecture and that Linus initially named the kernel "FREAX". Lastly, the article explains that due to its age, it is difficult to compile with modern toolchains.

Q&As

What are the system calls supported in Linux v0.01?
The system calls supported in Linux v0.01 are access, acct, alarm, break, brk, chdir, chmod, chown, chroot, close, creat, dup, dup2, execve, exit, fcntl, fork, fstat, ftime, getegid, geteuid, getgid, getpgrp, setsid, getpid, getppid, getuid, gtty, ioctl, kill, link, lock, lseek, mkdir, mknod, mount, mpx, nice, open, pause, phys, pipe, prof, ptrace, read, rename, rmdir, setgid, setpgid, setuid, setup, signal, stat, stime, stty, sync, time, times, ulimit, umask, umount, uname, unlink, ustat, utime, waitpid, and write.

What type of file system is supported in Linux v0.01?
The file system supported in Linux v0.01 is the MINIX file system.

How was the scheduler designed in Linux v0.01?
The scheduler in Linux v0.01 was based on a x86-specific feature called Task State Segment (TSS). It picks up the task with the largest counter value and switches to it. If all runnable tasks have counter value of 0, it updates each task's counter value by counter = (counter >> 1) + priority and restarts the loop.

What is the "FREAX" name mentioned in the article?
The "FREAX" name mentioned in the article is the original name of the Linux kernel.

Why is it difficult to compile Linux v0.01 with modern toolchains?
It is difficult to compile Linux v0.01 with modern toolchains because it uses older standards and features that are not supported by modern toolchains. It also uses x86-specific features that are no longer used for task management in x86-64 architecture.

AI Comments

👍 This article is a great way to explore the history of the Linux kernel and understand the evolution of its codebase.

👎 This article presents a lot of technical information in a fairly dense way, making it difficult for readers without a technical background to understand.

AI Discussion

Me: It's about exploring the internals of Linux v0.01. It discusses the system calls, the file system supported, the scheduler, and the kernel panic in 5 lines. It's really interesting to see how the first version of Linux was designed and implemented.

Friend: Wow, that's really fascinating. It's amazing to see how far Linux has come since then. What kind of implications does the article have?

Me: Well, the article highlights the importance of open source software. It took decades of hard work from many contributors to get to where Linux is today. It also shows the significance of the debate between Linus and Andrew Tanenbaum about the design of operating systems. This debate has had a huge impact on Linux and other open source software. Finally, the article shows how the concept of sockets was not implemented in the first version of Linux, and how some features like mount(2) were missing. This is important to understand the evolution of Linux and how it has evolved over time.

Action items

Download the tarball of Linux v0.01 from kernel.org and read the source code.
Research the debate between Linus and Andrew S. Tanenbaum about the design of operating systems.
Try to compile the kernel with modern toolchains and document the process.

Technical terms

Linux Kernel: The core of the Linux operating system, responsible for managing hardware and software resources.
v6.5-rc5: The latest version of the Linux kernel, consisting of 36 million lines of code.
v0.01: The first version of the Linux kernel, consisting of 10,239 lines of code.
System Calls: A type of function that allows a program to request services from the operating system.
Task State Segment (TSS): A x86-specific feature used for task management in x86-64 architecture.
Completely Fair Scheduler (CFS): A scheduling algorithm used in Linux to improve performance and fairness.
Kernel Panic: A situation in which the operating system is unable to function due to a critical error.
MINIX File System: The file system supported in Linux v0.01.
FREAX: The original name of the Linux kernel.
Programmable Interval Timer (PIT): A timer used in Linux v0.01.
x86 String Instructions: A set of instructions used to optimize string operations on x86 processors.