Slashdot Mirror

← Back to Stories (view on slashdot.org)

'Fuchsia Is Not Linux': Google Publishes Documentation Explaining Their New OS (xda-developers.com)

Posted by BeauHD on from the not-what-it-looks-like dept.

An anonymous reader quotes a report from XDA Developers: You've probably seen mentions of the Fuchsia operating system here and there since it has been in development for almost 2 years. It's Google's not-so-secretive operating system which many speculate will eventually replace Android. We've seen it grow from a barely functional mock-up UI in an app form to a version that actually boots on existing hardware. We've seen how much importance Google places on the project as veteran Android project managers are starting to work on it. But after all of this time, we've never once had either an official announcement from Google about the project or any documentation about it -- all of the information thus far has come as a result of people digging into the source code.

Now, that appears to be changing as Google has published a documentation page called "The Book." The page aims to explain what Fuchsia, the "modular, capability-based operating system" is and is not. The most prominent text on that page is a large section explaining that Fuchsia is NOT Linux, in case that wasn't clear already. Above that are several readme pages explaining Fuchsia's file systems, boot sequence, core libraries, sandboxing, and more. The rest of the page has sections explaining what the Zircon micro-kernel is and how the framework, storage, networking, graphics, media, user interface, and more are implemented.

5 of 245 comments (clear)

  1. Re:interesting by Anonymous Coward · · Score: 4, Informative

    Blackberry used QNX, a microkernel based OS used in lots of real-time applications.

    Yeah, the device failed, but not because of the microkernel.

  2. Fuchsia kernel (Zircon) is a lot like Windows by Anonymous Coward · · Score: 2, Informative

    Zircon has a unified system to manage the lifetime of, and control access to, all kernel objects. It feels very much like the Windows kernel. The way Zircon uses handles, and the zx_object_wait_one() and zx_object_wait_many() functions, really show the Windows influence. I personally think this is a Good Thing -- my disagreements with Windows lie mostly in user mode -- but YMMV.

    Just to be clear... I'm not saying Zircon is a Windows clone -- just that I see clear influence from Windows.

  3. Re:interesting by shoor · · Score: 4, Informative

    The early microkernels had problems, but a 2nd generation of 'L4' kernels, pioneered by Jochen Liedtke (who died an untimely death at age 48) seems to have gotten around that. From the wikipedia article on L4 microkernel family:

    The poor performance of first-generation microkernels, such as Mach, led a number of developers to re-examine the entire microkernel concept in the mid-1990s...
    Detailed analysis of the Mach bottleneck indicated that, among other things, its working set is too large: the IPC code expresses poor spatial locality; that is, it results in too many cache misses, of which most are in-kernel...
    Liedtke came to the conclusion that several other Mach concepts were also misplaced. By simplifying the microkernel concepts even further he developed the first L4 kernel which was primarily designed with high performance in mind. In order to wring out every bit of performance the entire kernel was written in assembly language, and its IPC was 20 times faster than Mach's.[4] Such dramatic performance increases are a rare event in operating systems, and Liedtke's work triggered new L4 implementations and work on L4-based systems at a number of universities and research institutes,

    --
    In theory, theory and practice are the same; in practice they're different. (Yogi Berra & A. Einstein)
  4. Re:interesting by zilym · · Score: 5, Informative

    Android is far away from Linux, but it still has the Linux kernel at its core. I recently wrote an app that uses Linux ioctls to talk to a USB device from native code in order to achieve minimal latency. Sure, I have to initially get things going from Java to obtain permissions in Android, but once I've got the file descriptor for the USB device I want to talk to, I'm off to the races.

  5. Re:interesting by religionofpeas · · Score: 3, Informative

    The problem with microkernel performance is not due to latency for process switching and message passing.

    The problem is the synchronization between different parts. Imagine for instance a multi-threaded filesystem. A filesystem as whole has a certain state. That state describes all the files and directories, file sizes and contents. Now imagine that one of the threads makes a change to the state. The problem is how to get that state update to all the other threads with a minimum of a delay.

    In a monolithic kernel, the problem is solved by getting a lock, update the state, and releasing the lock. It's a very simple and efficient operation.

    In a microkernel, you need to send messages around. You can optimize the message passing itself, but you'll still have the problem that the receiving thread is doing other things, and only handles the messages at certain points. While it is doing those other things, it's working with an outdated version of the state. Basically you're getting into the design of distributed filesystems/computing, and this is a very hairy subject. The complexity of the problem is much larger than just sticking to simple locking.

    The traditional solution is to keep the filesystem (and similar parts of the OS) in a single thread. This may be a viable solution on some platforms (perhaps a phone or tablet), but it will quickly run into scalability problems on a large, general purpose computer.