OctoX is a radical Rust implementation of a very old OS for RISC-V

Not solely are numerous editions of Version 6 UNIX, typically often known as V6 for brief, nonetheless being maintained – however new ones proceed to look.

Version 6 UNIX arrived in 1975, and it was the primary model of the brand new OS to see a lot widespread use outdoors of AT&T and a handful of analysis establishments. It’s the OS documented within the well-known “Lions book” [PDF], extra formally often known as A Commentary on the Sixth Edition Unix Operating System, and the origin of maybe probably the most well-known supply code remark of all time:

/*
 * You will not be anticipated to grasp this.
 */

(If you do not know the Lions e-book, and need to see the supply code subsequent to the commentary, there’s a extra interactive web-text model on GitHub.)

Perhaps surprisingly for such a primitive system from the mid-Seventies, a number of completely different fashionable OSes derived from V6 are nonetheless round and maintained immediately, primarily for college students studying about working system design. So do not get too excited simply but, OctoX is not some radical new OS. It’s maybe fairer to say it is a radical new implementation of a very old OS.

It springs from Xv6, which is the Massachusetts Institute of Technology’s venture to modernize V6 for its Operating System Engineering course. The snag is that V6 itself was carried out for the DEC PDP-11, and in a pre-standardized model of C besides. After a few years, the boffins at MIT determined to rewrite V6 in ANSI C for fashionable x86 {hardware}, and the end result was Xv6. Its supply code is nonetheless accessible, however the x86 model has been outmoded by a newer model for RISC-V.

These days, regardless of its legions of followers, C is typically deprecated as a techniques programming language, not less than for new techniques – a view described concisely by former Google researcher Cliff Biffle’s 2019 essay Prefer Rust to C/C++ for new code.

An indication of its rising maturity is that persons are finishing important tasks in it. A latest instance that impressed us is Andrea Bargi’s rjvm, which because the writer’s detailed weblog publish explains, is a tiny, toy OpenJDK 7 Java digital machine, written totally in Rust.

Impressive as that is, working techniques are simpler to grasp and reveal. Another instance Rust’s rising suitability for bold tasks is reimplementing Xv6 in Rust. One occasion is rxv64, whose title is, in true Unix model, a very terse self-description: it is xv6, reimplemented in Rust (thus the “r” on the start), concentrating on x86-64 (the “64” on the tip).

However, as its GitHub statistics illustrate, rxv64 is not a pure Rust venture:

Enter OctoX, whose stats illustrate a stage of purity that excites a sure sort of geek:

We additionally grinned wryly at this pithy description from Hacker News:

o8vm targets RISC-V, whereas rxv64 targets a legacy ISA.

As its writer Hayato Ohhashi says: “This is a learning project for me, and I will not be accepting pull requests until I consider the implementation complete.” As a demonstration and a proof of idea, although, it appears to be like very spectacular, if not terribly sensible – however practicality is not the aim right here.

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Unix did not finish with V6, of course, it simply appears to characterize a candy spot in dimension and complexity of OS design for many individuals, particularly college students. In 1979, V6 was adopted by V7, the primary model of Unix that was designed to be moveable to completely different machine architectures. V7 was the direct ancestor of Microsoft Xenix, and it additionally led to 2 completely different ports for DEC minicomputers: its PDP-11 model, V7M, later led to DEC Ultrix, and the VAX model, UNIX/32V, led to the BSD household.

When Caldera acquired the Unix supply code, it opened the supply of variations as much as and together with V7. A modernized x86-32 model is Robert Nordier’s v7/x86.

For some, V7 was the traditional model of Unix, and after that is when it turned bloated and business. In academia, its descendants, which borrowed extensively from BSD, have been collectively often known as “Research Unix” and have become open supply comparatively just lately.

The final model of Research Unix was V10. After that, the venture moved on to Plan 9 from Bell Labs. That continues immediately within the kind of 9front. Since we wrote about late 2022’s “the Golden Age of Ballooning”, the 9front builders have launched a new model, “Don’t Touch the Artwork”. The Reg FOSS desk nonetheless feels that 9front’s Plan 9 has a lot to show the modern Linux and BSD world, and we suggest überhacker Drew DeVault’s essay In reward of Plan 9, which got here a week after our personal article, for an perception into why. ®