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Updated: 14 min 23 sec ago

Deadline scheduler part 2 — details and usage

1 hour 34 min ago
Linux’s deadline scheduler is a global early deadline first scheduler for sporadic tasks with constrained deadlines. These terms were defined in the first part of this series. In this installment, the details of the Linux deadline scheduler and how it can be used will be examined.

Security updates for Friday

2 hours 17 min ago
Security updates have been issued by Arch Linux (bind, irssi, nrpe, perl-xml-libxml, and transmission-cli), CentOS (java-1.8.0-openjdk), Debian (awstats, libgd2, mysql-5.5, rsync, smarty3, and transmission), Fedora (keycloak-httpd-client-install and rootsh), and Red Hat (java-1.7.0-oracle and java-1.8.0-oracle).

Git v2.16.0

Thu, 01/18/2018 - 17:35
Git v2.16.0 is now available. "It is comprised of 509 non-merge commits since v2.15.0, contributed by 91 people, 26 of which are new faces." The release notes are included in the link below.

Wine 3.0 released

Thu, 01/18/2018 - 15:54
Version 3.0 of the Wine Windows emulation layer has been released. "This release represents a year of development effort and over 6,000 individual changes." Most of the improvements seem to be around Direct3D graphics, but it also now possible to package up Wine as an Android app; see the release notes for details.

[$] Shrinking the kernel with link-time optimization

Thu, 01/18/2018 - 12:36
This is the second article of a series discussing various methods of reducing the size of the Linux kernel to make it suitable for small environments. The first article provided a short rationale for this topic, and covered the link-time garbage collection, also called the ld --gc-sections method. We've seen that, though it is pretty straightforward, link-time garbage collection has issues of its own when applied to the kernel, making achieving optimal results more difficult than it is worth. In this article we'll have a look at what the compiler itself can do using link-time optimization.

Security updates for Thursday

Thu, 01/18/2018 - 10:17
Security updates have been issued by CentOS (linux-firmware and microcode_ctl), Fedora (icecat and transmission), Oracle (java-1.8.0-openjdk and microcode_ctl), Red Hat (java-1.8.0-openjdk), Scientific Linux (java-1.8.0-openjdk), Slackware (bind), SUSE (kernel), and Ubuntu (eglibc).

[$] Weekly Edition for January 18, 2018

Wed, 01/17/2018 - 20:14
The Weekly Edition for January 18, 2018 is available.

[$] Monitoring with Prometheus 2.0

Wed, 01/17/2018 - 13:15
Prometheus is a monitoring tool built from scratch by SoundCloud in 2012. It works by pulling metrics from monitored services and storing them in a time series database (TSDB). It has a powerful query language to inspect that database, create alerts, and plot basic graphs. Those graphs can then be used to detect anomalies or trends for (possibly automated) resource provisioning. Prometheus also has extensive service discovery features and supports high availability configurations. That's what the brochure says, anyway; let's see how it works in the hands of an old grumpy system administrator. I'll be drawing comparisons with Munin and Nagios frequently because those are the tools I have used for over a decade in monitoring Unix clusters.

Four stable kernels

Wed, 01/17/2018 - 11:51
Greg Kroah-Hartman has released stable kernels 4.14.14, 4.9.77, 4.4.112, and 3.18.92. All of them contain important fixes and users should upgrade.

Security updates for Wednesday

Wed, 01/17/2018 - 11:44
Security updates have been issued by Debian (bind9, wordpress, and xbmc), Fedora (awstats, docker, gifsicle, irssi, microcode_ctl, mupdf, nasm, osc, osc-source_validator, and php), Gentoo (newsbeuter, poppler, and rsync), Mageia (gifsicle), Red Hat (linux-firmware and microcode_ctl), Scientific Linux (linux-firmware and microcode_ctl), SUSE (kernel and openssl), and Ubuntu (bind9, eglibc, glibc, and transmission).

[$] A survey of some free fuzzing tools

Wed, 01/17/2018 - 11:13
Many techniques in software security are complicated and require a deep understanding of the internal workings of the computer and the software under test. Some techniques, though, are conceptually simple and do not rely on knowledge of the underlying software. Fuzzing is a useful example: running a program with a wide variety of junk input and seeing if it does anything abnormal or interesting, like crashing. Though it might seem unsophisticated, fuzzing is extremely helpful in finding the parsing and input processing problems that are often the beginning of a security vulnerability.

Analyzing the Linux boot process (

Tue, 01/16/2018 - 15:13
Alison Chaiken looks in detail at how the kernel boots on "Besides starting buggy spyware, what function does early boot firmware serve? The job of a bootloader is to make available to a newly powered processor the resources it needs to run a general-purpose operating system like Linux. At power-on, there not only is no virtual memory, but no DRAM until its controller is brought up."

[$] Deadline scheduling part 1 — overview and theory

Tue, 01/16/2018 - 10:57
The deadline scheduler enables the user to specify a realtime task's requirements using well-defined realtime abstractions, allowing the system to make the best scheduling decisions, guaranteeing the scheduling of realtime tasks even in higher-load systems. This article, the first in a series of two, provides an introduction to realtime scheduling (deadline scheduling in particular) and some of the theory behind it.

Security updates for Tuesday

Tue, 01/16/2018 - 10:40
Security updates have been issued by Debian (ca-certificates, gdk-pixbuf, and graphicsmagick), Fedora (qtpass), openSUSE (python-openpyxl and syncthing), Slackware (kernel), and Ubuntu (gdk-pixbuf).

LSFMM 2018 call for proposals

Mon, 01/15/2018 - 11:49
The 2018 Linux Storage, Filesystem, and Memory-Management Summit will be held April 23-25 in Park City, Utah. The call for proposals has just gone out with a tight deadline: they need to be received by January 31. "LSF/MM is an invitation-only technical workshop to map out improvements to the Linux storage, filesystem and memory management subsystems that will make their way into the mainline kernel within the coming years."

[$] Meltdown/Spectre mitigation for 4.15 and beyond

Mon, 01/15/2018 - 11:46
While some aspects of the kernel's defenses against the Meltdown and Spectre vulnerabilities were more-or-less in place when the problems were disclosed on January 3, others were less fully formed. Additionally, many of the mitigations (especially for the two Spectre variants) had not been seen in public prior to the disclosure, meaning that there was a lot of scope for discussion once they came out. Many of those discussions are slowing down, and the kernel's initial response has mostly come into focus. The 4.15 kernel will include a broad set of mitigations, while some others will have to wait for later; read on for details on where things stand.

[$] Active state management of power domains

Mon, 01/15/2018 - 11:35
The Linux kernel's generic power domain (genpd) subsystem has been extended to support active state management of the power domains in the 4.15 development cycle. Power domains were traditionally used to enable or disable power to a region of a system on chip (SoC) but, with the recent updates, they can control the clock rate or amount of power supplied to that region as well. These changes improve the kernel's ability to run the system's hardware at the optimal power level for the current workload.

Click below (subscribers only) for the full article contributed by Viresh Kumar.

Security updates for Monday

Mon, 01/15/2018 - 10:49
Security updates have been issued by Arch Linux (qtpass), Debian (libkohana2-php, libxml2, transmission, and xmltooling), Fedora (kernel and qpid-cpp), Gentoo (PolarSSL and xen), Mageia (flash-player-plugin, irssi, kernel, kernel-linus, kernel-tmb, libvorbis, microcode, nvidia-current, php & libgd, poppler, webkit2, and wireshark), openSUSE (gifsicle, glibc, GraphicsMagick, gwenhywfar, ImageMagick, libetpan, mariadb, pngcrush, postgresql94, rsync, tiff, and wireshark), and Oracle (kernel).

Kernel prepatch 4.15-rc8

Sun, 01/14/2018 - 19:17
The 4.15-rc8 kernel prepatch is out for testing. Among other things, it includes the "retpoline" mechanism intended to mitigate variant 2 of the Spectre vulnerability. Testing of this change will be hard, though, since it requires a version of GCC that almost nobody has — watch LWN for a full article in the near future. "I'm still hoping that this will be the last rc, despite all the Meltdown and Spectre hoopla. But we will just have to see, it obviously requires this upcoming week to not come with any huge surprises."

[$] Opening up the GnuBee open NAS system

Fri, 01/12/2018 - 11:37
GnuBee is the brand name for a line of open hardware boards designed to provide Linux-based network-attached storage. Given the success of the crowdfunding campaigns for the first two products, the GB-PC1 and GB-PC2 (which support 2.5 and 3.5 inch drives respectively), there appears to be a market for these devices. Given that Linux is quite good at attaching storage to a network, it seems likely they will perform their core function more than adequately. My initial focus when exploring my GB-PC1 is not the performance but the openness: just how open is it really? The best analogy I can come up with is that of a door with rusty hinges: it can be opened, but doing so requires determination.