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Linux kernel coverage at LWN (now outside the paywall)

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  • Flash storage topics

    At the 2018 Linux Storage, Filesystem, and Memory-Management Summit (LSFMM), Jaegeuk Kim described some current issues for flash storage, especially with regard to Android. Kim is the F2FS developer and maintainer, and the filesystem-track session was ostensibly about that filesystem. In the end, though, the talk did not focus on F2FS and instead ranged over a number of problem areas for Android flash storage.

    He started by noting that Universal Flash Storage (UFS) devices have high read/write speeds, but can also have high latency for some operations. For example, ext4 will issue a discard command but a UFS device might take ten seconds to process it. That leads the user to think that Android is broken, he said.

  • The ZUFS zero-copy filesystem

    At the 2018 Linux Storage, Filesystem, and Memory-Management Summit (LSFMM), Boaz Harrosh presented his zero-copy user-mode filesystem (ZUFS). It is both a filesystem in its own right and a framework similar to FUSE for implementing filesystems in user space. It is geared toward extremely low latency and high performance, particularly for systems using persistent memory.

    Harrosh began by saying that the idea behind his talk is to hopefully entice others into helping out with ZUFS. There are lots of "big iron machines" these days, some with extremely fast I/O paths (e.g. NVMe over fabrics with throughput higher than memory). "For some reason" there may be a need to run a filesystem in user space but the current interface is slow because "everyone is copy happy", he said.

  • A filesystem "change journal" and other topics

    At the 2017 Linux Storage, Filesystem, and Memory-Management Summit (LSFMM), Amir Goldstein presented his work on adding a superblock watch mechanism to provide a scalable way to notify applications of changes in a filesystem. At the 2018 edition of LSFMM, he was back to discuss adding NTFS-like change journals to the kernel in support of backup solutions of various sorts. As a second topic for the session, he also wanted to discuss doing more performance-regression testing for filesystems.

    Goldstein said he is working on getting the superblock watch feature merged. It works well and is used in production by his employer, CTERA Networks, but there is a need to get information about filesystem changes even after a crash. Jan Kara suggested that what was wanted was an indication of which files had changed since the last time the filesystem changes were queried; Goldstein agreed.

  • Will staging lose its Lustre?

    The kernel's staging tree is meant to be a path by which substandard code can attract increased developer attention, be improved, and eventually find its way into the mainline kernel. Not every module graduates from staging; some are simply removed after it becomes clear that nobody cares about them. It is rare, though, for a project that is actively developed and widely used to be removed from the staging tree, but that may be about to happen with the Lustre filesystem.

    The staging tree was created almost exactly ten years ago as a response to the ongoing problem of out-of-tree drivers that had many users but which lacked the code quality to get into the kernel. By giving such code a toehold, it was hoped, the staging tree would help it to mature more quickly; in the process, it would also provide a relatively safe place for aspiring kernel developers to get their hands dirty fixing up the code. By some measures, staging has been a great success: it has seen nearly 50,000 commits contributed by a large community of developers, and a number of drivers have, indeed, shaped up and moved into the mainline. The "ccree" TrustZone CryptoCell driver graduated from staging in 4.17, for example, and the visorbus driver moved to the mainline in 4.16.

  • Statistics from the 4.17 kernel development cycle

    The 4.17 kernel appears to be on track for a June 3 release, barring an unlikely last-minute surprise. So the time has come for the usual look at some development statistics for this cycle. While 4.17 is a normal cycle for the most part, it does have one characteristic of note: it is the third kernel release ever to be smaller (in terms of lines of code) than its predecessor.

    The 4.17 kernel, as of just after 4.17-rc7, has brought in 13,453 non-merge changesets from 1,696 developers. Of those developers, 256 made their first contribution to the kernel in this cycle; that is the smallest number of first-time developers since 4.8 (which had 237). The changeset count is nearly equal to 4.16 (which had 13,630), but the developer count is down from the 1,774 seen in the previous cycle.

  • Deferring seccomp decisions to user space

    There has been a lot of work in recent years to use BPF to push policy decisions into the kernel. But sometimes, it seems, what is really wanted is a way for a BPF program to punt a decision back to user space. That is the objective behind this patch set giving the secure computing (seccomp) mechanism a way to pass complex decisions to a user-space helper program.

    Seccomp, in its most flexible mode, allows user space to load a BPF program (still "classic" BPF, not the newer "extended" BPF) that has the opportunity to review every system call made by the controlled process. This program can choose to allow a call to proceed, or it can intervene by forcing a failure return or the immediate death of the process. These seccomp filters are known to be challenging to write for a number of reasons, even when the desired policy is simple.

    Tycho Andersen, the author of the "seccomp trap to user space" patch set, sees a number of situations where the current mechanism falls short. His scenarios include allowing a container to load modules, create device nodes, or mount filesystems — with rigid controls applied. For example, creation of a /dev/null device would be allowed, but new block devices (or almost anything else) would not. Policies to allow this kind of action can be complex and site-specific; they are not something that would be easily implemented in a BPF program. But it might be possible to write something in user space that could handle decisions like these.

More in Tux Machines

Mozilla: Firefox Privacy Features and the Cost of Proprietary Software for Communication

  • Save and update passwords in Private Browsing with Firefox
    Private browsing was invented 14 years ago, making it possible for users to close a browser window and erase traces of their online activity from their computers. Since then, we’ve bundled in various levels of tracking protection and privacy control. While that’s great, some basic browser functionality pieces were missing from the Private Browsing Mode experience, namely giving you the option to save logins and passwords and giving you the power to choose which extensions you wanted enabled.
  • No-Judgement Digital Definitions: What is Cryptocurrency?
    Cryptocurrency, cryptomining. We hear these terms thrown around a lot these days. It’s a new way to invest. It’s a new way to pay. It’s a new way to be deeply confused. To many of us, crypto-things sound like technobabble from sci fi movie. If you’re used to thinking about money as something that is issued by your government, kept in a bank and then traded for goods and services, then wrapping your head around cryptocurrency might be a bit of work, but we can do it!
  • Let Firefox help you block cryptominers from your computer
    Is your computer fan spinning up for no apparent reason? Your electricity bill inexplicably high? Your laptop battery draining much faster than usual? It may not be all the Netflix you’re binging or a computer virus. Cryptocurrency miners may be using your computer’s resources to generate cryptocurrency without your consent. We know it sounds like something out of a video game or one of those movies that barely gets technology right, but as much as cryptomining may sound like fiction, the impact on your life can be very real.
  • How to block fingerprinting with Firefox
    If you wonder why you keep seeing the same ad, over and over, the answer could be fingerprinting. Fingerprinting is a type of online tracking that’s different from cookies or ordinary trackers. This digital fingerprint is created when a company makes a unique profile of your computer, software, add-ons, and even preferences. Your settings like the screen you use, the fonts installed on your computer, and even your choice of a web browser can all be used to create a fingerprint.
  • Firefox 67: Dark Mode CSS, WebRender, and more
    Firefox 67 is available today, bringing a faster and better JavaScript debugger, support for CSS prefers-color-scheme media queries, and the initial debut of WebRender in stable Firefox.
  • The Cost of Fragmented Communication
    Mozilla recently announced that we are planning to de-commission irc.mozilla.org in favour of a yet to be determined solution. As a long time user and supporter of IRC, this decision causes me some melancholy, but I 100% believe that it is the right call. Moreover, having had an inside glimpse at the process to replace it, I’m supremely confident whatever is chosen will be the best option for Mozilla’s needs. I’m not here to explain why deprecating IRC is a good idea. Other people have already done so much more eloquently than I ever could have. I’m also not here to push for a specific replacement. Arguing over chat applications is like arguing over editors or version control. Yes, there are real and important differences from one application to the next, but if there’s one thing we’re spoiled for in 2019 it’s chat applications. Besides, so much time has been spent thinking about the requirements, there’s little anyone could say on the matter that hasn’t already been considered for hours.

Firefox 67.0 Released

  • Version 67.0, first offered to Release channel users on May 21, 2019
  • Latest Firefox Release is Faster than Ever
    With the introduction of the new Firefox Quantum browser in 2017 we changed the look, feel, and performance of our core product. Since then we have launched new products to complement your experience when you’re using Firefox and serve you beyond the browser. This includes Facebook Container, Firefox Monitor and Firefox Send. Collectively, they work to protect your privacy and keep you safe so you can do the things you love online with ease and peace of mind. We’ve been delivering on that promise to you for more than twenty years by putting your security and privacy first in the building of products that are open and accessible to all. Today’s new Firefox release continues to bring fast and private together right at the crossroads of performance and security. It includes improvements that continue to keep Firefox fast while giving you more control and assurance through new features that your personal information is safe while you’re online with us.
  • Firefox 67.0 Released, ownCloud Announces New Server Version 10.2, Google Launches "Glass Enterprise Edition 2" Headset, Ubuntu Expands Its Kernel Uploader Team and Kenna Security Reports Almost 20% of Popular Docker Containers Have No Root Password
    Firefox 67.0 was released today. From the Mozilla blog: "Today's new Firefox release continues to bring fast and private together right at the crossroads of performance and security. It includes improvements that continue to keep Firefox fast while giving you more control and assurance through new features that your personal information is safe while you're online with us." You can download it from here, and see the release notes for details.
  • Firefox 67.0 Released, Upgrading to Dav1d AV1 Decoder
    Mozilla Firefox 67.0 was released today with performance improvements and some new features.
  • Firefox 67.0 Released With Better Performance, Switches To Dav1d AV1 Decoder
    Mozilla set sail Firefox 67.0 this morning as the newest version of this web browser and the update is heavy on the feature front. Firefox 67.0 brings a number of performance improvements, the ability to block known cryptominers/fingerprinters, better keyboard accessibility, usability/security enhancements to Private Browsing, various ease-of-use improvements, switching to DAV1D as its AV1 video decoder, FIDO U2F API support, security fixes, and various JavaScript API additions.
  • Firefox 67 released
    The Mozilla blog takes a look at the Firefox 67 release.

today's howtos

Tails 3.14 is out

This release fixes many security vulnerabilities. You should upgrade as soon as possible. Read more