Search Results: "ag"

14 December 2015

Matthias Klumpp: AppStream/DEP-11 fully supported in Debian now!

AppStream on DebianBack in 2011, when the AppStream meeting in N rnberg had just happened, I published the DEP-11 (Debian Extension Project 11) draft together with Michael Vogt and Julian Andres Klode, as an approach to implement AppStream in Debian. Back then, the FTPMasters team rejected the suggestion to use the official XML specification, and so the DEP-11 specification was adapted to be based on YAML instead of XML. This wasn t much of a big deal, since the initial design of DEP-11 was to be a superset of the AppStream specification, so it wasn t meant to be exactly like AppStream anyway. AppStream back then was only designed for applications (as in stuff that provides a .desktop file ), but with DEP-11 we aimed for much more: DEP-11 should also describe fonts, drivers, pkg-config files and other metadata, so in the end one would be able to ask the package manager meaningful questions like is the firmware of device X installed? or request actions such as please install me the GIMP , making it unnecessary to know package names at all, and making packages a mere implementation detail. Then, GNOME-Software happened and demanded all these features. Back then, I was the de-facto maintainer of the AppStream upstream project already, but didn t feel like being the maintainer yet, so I only curated the existing specification, without extending it much. The big push forward GNOME-Software created changed that dramatically, and with me taking control of the specification and documenting it properly, the very essence of DEP-11 became AppStream (that was around the AppStream 0.6 release). So today, DEP-11 is mainly a YAML-based version of the AppStream XML specification. AppStream XML and DEP-11 YAML are implemented by two projects, GLib and Qt libraries exist to access the metadata and AppStream is used by the software centers of GNOME, KDE and Elementary. Today there are two things to celebrate for me: First of all, there is the release of AppStream 0.9 (that happened last Saturday already), which brings some nice improvements to the API for developers and some micro-optimizations to speed up Xapian database queries. Yay! The second thing is full DEP-11 support in Debian! This means that you don t need to copy metadata around manually, or install extra packages: All you need to do is to install the appstream package, everything else is done for you, and the data is kept up to date automatically. This is made possible by APT 1.1 (thanks to the whole APT team!), some dedicated support for it in AppStream directly, the work of our Sysadmin team at Debian, which set up infrastructure to build the metadata automatically, as well as our FTPMasters team where Joerg helped with the final steps of getting the metadata into the archive. That AppStream data is now in the archive doesn t mean we live in a perfect utopia yet there are still issues to be handled, but all the major work is done now and we can now gradually improve the data generator and tools and squash the remaining bugs. And another item from the good news department: It s highly likely that Ubuntu will follow Debian in AppStream/DEP-11 support with the upcoming Xenial release! But how can I make use of the new metadata? Just install the appstream package everything is done for you! Another easy way is to install GNOME-Software, which makes use of the new metadata already. KDE Discover in Debian does not enable support for AppStream yet, this will likely come later. If you prefer to use the command-line, you can now use commands like 
sudo appsteamcli install org.kde.kate.desktop
This will simply install the Kate text editor. Who wants some statistics? At time the Debian Sid/Unstable suite contains 1714 valid software components. It could be even more if the errors generated during metadata extraction would be resolved. For that, the metadata generator has a nice statistics page, showing the amount of each hint type in the suite and the development of the available software components in Debian and the hint types count over time (this plot feature was just added recently, so we are still a bit low on data). For packagers and interested upstreams, the data extractor creates detailed reports for each package, explaining why data was not included and how to fix the issue (in case something is unclear, please file a bug report and/or get in contact with me). In summary Thanks to everyone who helped to make this happen! For me this project means a lot, when writing this blog post I realized that I am basically working on it for almost 5 years (!) now (and the idea is even older). Seeing it to grow to such a huge success in other distributions was a joy, but now Debian can join the game with first-class AppStream support as well, which makes me even happier. Afterall Debian is the distribution I feel most at home. There is still lots of work to do (and already a few bugs known), but the hardest part of the journey is done let s walk into a bright future with AppStream!

Guido G nther: Creating views in Jenkins using jenkins-job-builder-addons

I'm often using jenkins-job-builder to automatically create jenkins jobs since writing them in YAML is more comfortable then doing large amounts of jobs in the GUI, it serves consistency and helps automation. For views and build pipelines I so far resorted to other tools (like templates in the config management tool at use) but now there's jenkins-job-builder-addons by jimbydamonk. Creating a delivery pipeline view and the "All" view then gets as simple as: 
- job:
    name: MyApp
    project-type: folder
    views:
      - delivery_pipeline:
          filter-executors: false
          filter-queue: false
          folder: true
          components:
            - name: Deploy
              first-job: app-deploy-test
          name: myapp-deploy-pipeline
          build-view-title: "MyApp Deploy Pipeline"
          number-of-pipelines: 3
          show-aggregated-pipeline: true
          number-of-columns: 1
          sorting: none
          show-avatars: false
          update-interval: 1
          allow-manual-triggers: true
          show-total-buildtime: true
          allow-rebuild: true
          allow-pipeline-start: true
      - all:
         folder: true
         name: All
This also uses the folder plugin to make sure the views end up in separate files. It currently needs a slightly patched jenkins-job-builder with this patch applied. Putting this here since I hit jenkins-job-builder-addons mostly by accident. Once jenkins-job-builder catched up I'll look into packaging this for Debian.

13 December 2015

Gregor Herrmann: RC bugs 2015/38-50

it looks like this autumn was not my best blogging time: this is the first posting in 3 months. anyway, I wanted to give a quick overview about my work on RC bugs. again nothing exciting, mostly just trying to fix the ones popping up in the pkg-perl team.

Chris Lamb: try.diffoscope.org

If you haven't already come across it, diffoscope is a tool that reveals what makes files or directories actually different. It recursively unpacks archives of many kinds, transforming binary formats into more human-readable forms in order to make it easier to compare them. It can compare two tarballs, ISO images, PDF, squashfs images, etc. Anyway, yesterday I hacked together try.diffoscope.org which lets anyone easily try out and share these in-depth comparisons using just a web browser. The underlying idea is not only to provide a useful service, but also that it will publicise and spread the usage of diffoscope, resulting in net improvements that will feed back into the Reproducible Builds effort. As usual, patches welcome.

Vasudev Kamath: Mount ordering and automount options in systemd

Just to give a brief recap of why I'm writing this post, I've to describe a brief encounter I had with systemd which rendered my system unbootable. I first felt its systemd's problem but later figured out it was my mistake. So below is brief story divided into 2 sections Problem and Solution. Here Problem describes issue I faced with systemd and Solution discusses the .mount and .automount suffix files used by systemd.
Problem I have several local bin folders and I don't want to modify PATH environment variable adding every other folder path. I first started using aufs as alternative to symlinks or modifying PATH variable. Recently I learnt about much more light weight union fs which is in kernel, overlayfs. And Google led me to Arch wiki article which showed me a fstab entry like below 
overlay        /usr/local/bin        overlay noauto,x-systemd.automount,lowerdir=/home/vasudev/Documents/utilities/bin,upperdir=/home/vasudev/Documents/utilities/jonas-bin,workdir=/home/vasudev/Documents/utilities/bin-overlay    0       0
And after adding this entry, on next reboot systemd is not able to mount my LVM home and swap partition. It does however mount root partition. It gives me emergency target but login never returns. So without any alternative I had to reinstall the system. But funnily enough I started encountering the same issue (yeah after I had added above entry into fstab). Yeah that time I never thought that its culprit. My friend Ritesh finally got my system booting after the weird x-systemd.automount option. I never investigated further that time on why this problem occurred.
Solution After re-encounter with similar problem and some other project I read the manual on systemd.mount, systemd-fstab-generator and systemd.automount and I had some understanding of what really went wrong in my case above. So now let us see what really is happening. All the above happened because, systemd translates the /etc/fstab into .mount units at run time using systemd-fstab-generator. Every entry in fstab translates into a file named after the mount point. The / in the path of the mount point is replaced by a -. So / mount point is named as -.mount and /home is named as home.mount and /boot becomes boot.mount. All these files can be seen in directory /run/systemd/generator. And all these mount points are needed by local-fs.target , if any of these mount points fail, local-fs.target fails. And if local-fs.target fails it will invoke emergency.target. systemd-fstab-generator manual suggests the ordering information in /etc/fstab is discarded. That means if you have union mounts, bind mounts or fuse mounts in the fstab which is normally at end of fstab and uses path from /home or some other device mount points it will fail to get mounted. This happens because systemd-fstab-generator didn't consider the ordering in fstab. This is what happened in my case my overlay mount point which is usr-local-bin.mount was some how happened to be tried before home.mount because there is no explicit dependency like Requires= or After= was declared. When systemd tried to mount it the path required under /home were not really present hence failed which in return invoked emergency.target as usr-local-bin.mount is Requires= dependency for local-fs.target. Now what I didn't understand is why emregency.target never gave me the root shell after entering login information. I feel that this part is unrelated to the problem I described above and is some other bug. To over come this what we can do is provided systemd-fstab-generator some information on dependency of each mount point. systemd.mount manual page suggests several such options. One which I used in my case is x-systemd.requires which should be placed in options column of fstab and specify the mount point which is needed before it has to be mounted. So my overlay fs entry translates to something like below 
overlay        /usr/local/bin        overlay noauto,x-systemd.requires=/home,x-systemd.automount,lowerdir=/home/vasudev/Documents/utilities/bin,upperdir=/home/vasudev/Documents/utilities/jonas-bin,workdir=/home/vasudev/Documents/utilities/bin-overlay   0       0
There is another special option called x-systemd.automount this will make systemd-fstab-generator to create a .automount file for this mount point. What does systemd.automount do? It achieves on-demand file mounting and parallelized file system mounting. Something similar to systemd.socket the file system will be mounted when you access the mount point for first time. So now if you try to see dependency of usr-local-bin.mount you will see following. 
systemctl show -p After usr-local-bin.mount
After=-.mount systemd-journald.socket local-fs-pre.target system.slice usr-local-bin.automount
This means now usr-local-bin.mount depends on usr-local-bin.automount. And let us see what usr-local-bin.automount needs. 
systemctl show -p Requires usr-local-bin.automount
Requires=-.mount home.mount
systemctl show -p After usr-local-bin.automount
After=-.mount home.mount
So clearly usr-local-bin.automount is activated after -.mount and home.mount is activated. Similar can be done for any bind mounts or fuse mounts which require other mount points before it can be mounted. Also note that x-systemd.autmount is not mandatory option for declaring dependencies, I used it just to make sure /usr/local/bin is mounted only when its really needed.
Conclusion A lot of traditional way has been changed by systemd. I never understood why my system failed to boot in first place this happened because I was not really aware of how systemd works and was trying to debug the problem with traditional approach. So there is really a learning curve involved for every sysadmin out there who is going to use systemd. Most of them will read documentation before hand but others like me will learn after having a situation like above. :-). So systemd interfering into /etc/fstab is good?. I don't know but since systemd parallelizes the boot procedure something like this is really needed. Is there a way to make systemd not touch /etc/fstab?. Yes there is you need to pass fstab=0 option in kernel command line and systemd-fstab-generator doesn't create any .mount or .swap files from your /etc/fstab. !NB Also it looks like x-systemd.requires option was introduced recently and is not available in systemd <= 215 which is default in Jessie. So how do you declare dependencies in Jessie system?. I don't have any answer!. I did read that x-systemd.automount which is available in those versions of systemd can be used, but I'm yet to experiment this. If it succeeds I will write a post on it.

Robert Edmonds: Works with Debian: Intel SSD 750, AMD FirePro W4100, Dell P2715Q

I recently installed new hardware in my primary computer running Debian unstable. The disk used for the / and /home filesystem was replaced with an Intel SSD 750 series NVM Express card. The graphics card was replaced by an AMD FirePro W4100 card, and two Dell P2715Q monitors were installed. Intel SSD 750 series NVM Express card This is an 800 GB SSD on a PCI-Express x4 card (model number SSDPEDMW800G4X1) using the relatively new NVM Express interface, which appears as a /dev/nvme* device. The stretch alpha 4 Debian installer was able to detect and install onto this device, but grub-installer 1.127 on the installer media was unable to install the boot loader. This was due to a bug recently fixed in 1.128: 
grub-installer (1.128) unstable; urgency=high
  * Fix buggy /dev/nvme matching in the case statement to determine
    disc_offered_devfs (Closes: #799119). Thanks, Mario Limonciello!
 -- Cyril Brulebois <kibi@debian.org>  Thu, 03 Dec 2015 00:26:42 +0100
I was able to download and install the updated .udeb by hand in the installer environment and complete the installation. This card was installed on a Supermicro X10SAE motherboard, and the UEFI BIOS was able to boot Debian directly from the NVMe card, although I updated to the latest available BIOS firmware prior to the installation. It appears in lspci like this: 
02:00.0 Non-Volatile memory controller: Intel Corporation PCIe Data Center SSD (rev 01)
(prog-if 02 [NVM Express])
    Subsystem: Intel Corporation SSD 750 Series [Add-in Card]
    Flags: bus master, fast devsel, latency 0
    Memory at f7d10000 (64-bit, non-prefetchable) [size=16K]
    Expansion ROM at f7d00000 [disabled] [size=64K]
    Capabilities: [40] Power Management version 3
    Capabilities: [50] MSI-X: Enable+ Count=32 Masked-
    Capabilities: [60] Express Endpoint, MSI 00
    Capabilities: [100] Advanced Error Reporting
    Capabilities: [150] Virtual Channel
    Capabilities: [180] Power Budgeting <?>
    Capabilities: [190] Alternative Routing-ID Interpretation (ARI)
    Capabilities: [270] Device Serial Number 55-cd-2e-41-4c-90-a8-97
    Capabilities: [2a0] #19
    Kernel driver in use: nvme
The card itself appears very large in marketing photos, but this is a visual trick: the photographs are taken with the low-profile PCI bracket installed, rather than the standard height PCI bracket which it ships installed with. smartmontools fails to read SMART data from the drive, although it is still able to retrieve basic device information, including the temperature: 
root@chase 0 :~# smartctl -d scsi -a /dev/nvme0n1
smartctl 6.4 2015-06-04 r4109 [x86_64-linux-4.3.0-trunk-amd64] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Vendor:               NVMe
Product:              INTEL SSDPEDMW80
Revision:             0135
Compliance:           SPC-4
User Capacity:        800,166,076,416 bytes [800 GB]
Logical block size:   512 bytes
Rotation Rate:        Solid State Device
Logical Unit id:      8086INTEL SSDPEDMW800G4                     1000CVCQ531500K2800EGN  
Serial number:        CVCQ531500K2800EGN
Device type:          disk
Local Time is:        Sun Dec 13 01:48:37 2015 EST
SMART support is:     Unavailable - device lacks SMART capability.
=== START OF READ SMART DATA SECTION ===
Current Drive Temperature:     31 C
Drive Trip Temperature:        85 C
Error Counter logging not supported
[GLTSD (Global Logging Target Save Disable) set. Enable Save with '-S on']
Device does not support Self Test logging
root@chase 4 :~#
Simple tests with cat /dev/nvme0n1 >/dev/null and iotop show that the card can read data at about 1 GB/sec, about twice as fast as the SATA-based SSD that it replaced. apt/dpkg now run about as fast on the NVMe SSD as they do on a tmpfs. Hopefully this device doesn't at some point require updated firmware, like some infamous SSDs have. AMD FirePro W4100 graphics card This is a graphics card capable of driving multiple DisplayPort displays at "4K" resolution and at a 60 Hz refresh rate. It has four Mini DisplayPort connectors, although I only use two of them. It was difficult to find a sensible graphics card. Most discrete graphics cards appear to be marketed towards video gamers who apparently must seek out bulky cards that occupy multiple PCI slots and have excessive cooling devices. (To take a random example, the ASUS STRIX R9 390X has three fans and brags about its "Mega Heatpipes".) AMD markets a separate line of "FirePro" graphics cards intended for professionals rather than gamers, although they appear to be based on the same GPUs as their "Radeon" video cards. The AMD FirePro W4100 is a normal half-height PCI-E card that fits into a single PCI slot and has a relatively small cooler with a single fan. It doesn't even require an auxilliary power connection and is about the same dimensions as older video cards that I've successfully used with Debian. It was difficult to determine whether the W4100 card was actually supported by an open source driver before buying it. The word "FirePro" appears nowhere on the webpage for the X.org Radeon driver, but I was able to find a "CAPE VERDE" listed as an engineering name which appears to match the "Cape Verde" code name for the FirePro W4100 given on Wikipedia's List of AMD graphics processing units. This explains the "verde" string that appears in the firmware filenames requested by the kernel (available only in the non-free/firmware-amd-graphics package): 
[drm] initializing kernel modesetting (VERDE 0x1002:0x682C 0x1002:0x2B1E).
[drm] Loading verde Microcode
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_pfp.bin
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_me.bin
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_ce.bin
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_rlc.bin
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_mc.bin
radeon 0000:01:00.0: firmware: direct-loading firmware radeon/verde_smc.bin
The card appears in lspci like this: 
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde GL [FirePro W4100]
(prog-if 00 [VGA controller])
    Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device 2b1e
    Flags: bus master, fast devsel, latency 0, IRQ 55
    Memory at e0000000 (64-bit, prefetchable) [size=256M]
    Memory at f7e00000 (64-bit, non-prefetchable) [size=256K]
    I/O ports at e000 [size=256]
    Expansion ROM at f7e40000 [disabled] [size=128K]
    Capabilities: [48] Vendor Specific Information: Len=08 <?>
    Capabilities: [50] Power Management version 3
    Capabilities: [58] Express Legacy Endpoint, MSI 00
    Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
    Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
    Capabilities: [150] Advanced Error Reporting
    Capabilities: [200] #15
    Capabilities: [270] #19
    Kernel driver in use: radeon
The W4100 appears to work just fine, except for a few bizarre error messages that are printed to the kernel log when the displays are woken from power saving mode: 
[Sun Dec 13 00:24:41 2015] [drm:si_dpm_set_power_state [radeon]] *ERROR* si_enable_smc_cac failed
[Sun Dec 13 00:24:41 2015] [drm:si_dpm_set_power_state [radeon]] *ERROR* si_enable_smc_cac failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link status failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link status failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
[Sun Dec 13 00:24:41 2015] [drm:si_dpm_set_power_state [radeon]] *ERROR* si_enable_smc_cac failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link status failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link status failed
[Sun Dec 13 00:24:41 2015] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
There don't appear to be any ill effects from these error messages, though. I have the following package versions installed: 
 / Name                          Version             Description
+++-=============================-===================-================================================
ii  firmware-amd-graphics         20151207-1          Binary firmware for AMD/ATI graphics chips
ii  linux-image-4.3.0-trunk-amd64 4.3-1~exp2          Linux 4.3 for 64-bit PCs
ii  xserver-xorg-video-radeon     1:7.6.1-1           X.Org X server -- AMD/ATI Radeon display driver
The Supermicro X10SAE motherboard has two PCI-E 3.0 slots, but they're listed as functioning in either "16/NA" or "8/8" mode, which apparently means that putting anything in the second slot (like the Intel 750 SSD, which uses an x4 link) causes the video card to run at a smaller x8 link width. This can be verified by looking at the widths reported in the "LnkCap" and "LnkSta" lines in the lspci -vv output: 
root@chase 0 :~# lspci -vv -s 01:00.0   egrep '(LnkCap LnkSta):'
        LnkCap: Port #0, Speed 8GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
        LnkSta: Speed 8GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
root@chase 0 :~#
I did not notice any visible artifacts or performance degradation because of the smaller link width. The sensors utility from the lm-sensors package is capable of reporting the temperature of the GPU: 
root@chase 0 :~# sensors radeon-pci-0100
radeon-pci-0100
Adapter: PCI adapter
temp1:        +55.0 C  (crit = +120.0 C, hyst = +90.0 C)
root@chase 0 :~#
Dell P2715Q monitors Two new 27" Dell monitors with a native resolution of 3840x2160 were attached to the new graphics card. They replaced two ten year old Dell 2001FP monitors with a native resolution of 1600x1200 that had experienced burn-in, providing 4.32 times as many pixels. (TV and monitor manufacturers now shamelessly refer to the 3840x2160 resolution as "4K" resolution even though neither dimension reaches 4000 pixels.) There was very little to setup beyond plugging the DisplayPort inputs on these monitors into the DisplayPort outputs on the graphics card. Most of the setup involved reconfiguring software to work with the very high resolution. X.org, for tl;dr CLOSED NOTABUG reasons doesn't set the DPI correctly. These monitors have ~163 DPI resolution, so I added -dpi 168 to /etc/X11/xdm/Xservers. (168 is an even 1.75x multiple of 96.) Software like Google Chrome and xfce4-terminal rendered fonts and graphical elements at the right size, but other software like notion, pidgin, and virt-manager did not fully understand the high DPI. E.g., pidgin renders fonts at the correct size, but icons are too small. The default X cursor was also too small. To fix this, I installed the dmz-cursor-theme package, ran update-alternatives --config x-cursor-theme and selected /usr/share/icons/DMZ-Black/cursor.theme as the cursor theme. Overall, these displays are much brighter and more readable than the ones they replaced.

12 December 2015

Daniel Pocock: TADHack Paris - 12-13 December 2015

I'm currently in Paris for TADHack, an opportunity to collaborate on a range of telephony APIs and services. People can also win prizes by doing something innovative with the platforms promoted by the sponsors. This has been a great opportunity to raise awareness of the RTC Quick Start Guide, introduce people to DruCall and JSCommunicator and identify other opportunities for business and technical collaboration. If you are in Paris, it is not too late to register and participate, please see the TADHack web site for details.
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11 December 2015

Matthias Klumpp: What s up in Tanglu?

tanglu logo pureIt is time again for another Tanglu blogpost (to be honest, this article is pretty much overdue ). I want to shine a spotlight on the work that s done in Tanglu, be it ongoing or past work done for the new release. Why is the new release taking longer than usual? As you might have noticed, usually a new Tanglu release (Tanglu 4 Dasyatis ) should be released this month. We decided a while ago, however, to defer the release and are now aiming for an release in February / March 2016. Reason for this change in schedule is the GCC 5 transition (and more importantly the huge amount of follow-up transitions) as well as some other major infrastructure tasks, which we would like to complete and give them a good amount of testing before releasing. Also, some issues with our build system, and generally less build power than in previous releases is a problem (At least the Debile build-system issues could be worked around or solved). The hard disk crash in the forum and bugtracking server also delayed the start of the Tanglu 4 development process a lot. In all of these tasks, manpower is of course the main problem Software Tasks General infrastructure tasks Improvements on Synchrotron Synchrotron, the software which is synchronizing the Tanglu archive with the Debian archive, received a few tweaks to make it more robust and detect installability of packages more reliably. We also run it more often now. Rapidumo improvements Rapidumo is a software written to complement dak (the Debian Archive Kit) in managing the Tanglu archive. It performs automatic QA tasks on the archive and provides a collection of tools to perform various tasks (like triggering package rebuilds). For Tanglu 4, we sometimes drop broken packages from the archive now, to speed up transitions and to remove packages which got uninstallable more quickly. Packages removed from the release suite still have a chance to enter it again, but they need to go through Tanglu s staging area again first. The removal process is currently semiautomatic, to avoid unneccessary removals and breakage. Rapidumo could benefit from some improvements and an interactive web interface (as opposed to static HTML pages) would be nice. Some early work on this is done, but not completed (and has a very low priority at the moment). DEP-11 integration There will be a bigger announcement on AppStream and DEP-11 in the next days, so I keep this terse: Tanglu will go for full AppStream integration with the next release, which means no more packaged metadata, but data placed directly in the archive. Work on this has started in Tanglu, but I needed to get back to the drawing board with it, to incorporate some new ideas for using synergies with Debian on generating the DEP-11 metadata. Phabricator Phabricator has been integrated well into our infrastructure, but there are still some pending tasks. E.g. we need subprojects in Phabricator, and a more powerful Conduit interface. Those are upstream bugs on Phabricator, and are actively being worked on. As soon as the missing features are available in Phabricator, we will also pursue the integration of Tanglu bug information with the Debian DistroTracker, which was discussed at DebConf this summer. UEFI support UEFI support is a tricky beast. Full UEFI support is a release-goal for Tanglu 4 (so we won t release without it). At time, our Live-CDs start on pure EFI systems, but there are several reported issues with the Calamares live-installer as well as Debian-Installer, which fails to install GRUB correctly. Work on resolving these problems is ongoing. Major LiveCD rework Tanglu 4 will ship with improved live-cds, which e.g. allow selecting the preferred locale early in the bootloader. We switched from live-boot to manage our live sessions to casper, the same tool which is also used in Ubuntu. Casper fixed a few issues we had, and brought some new, but overall using it was a good choice and work on making top-notch live-cds is progressing well. KDE Plasma Integration of the latest Plasma release is progressing, but its speed has slowed down since fewer people are working on it. If you want to help Tanglu s KDE Workspace integration, please help! For the upcoming release, the Plasma 5 packages which we created based on a collaboration with Kubuntu for the previous Tanglu 3 release have been merged with their Debian counterparts. This action fortunately was possible without major problems. Now Tanglu is (mostly) using the same Plasma 5 packages as Debian again (lots of Kudos go the the Kubuntu and Debian Qt/KDE packagers!). GNOME The same re-merge with Debian has been done on Tanglu s GNOME flavor (Tanglu also shipped with a more recent GNOME release than Debian in Tanglu 3). So Tanglu 4 GNOME and Debian Testing GNOME are at (almost) the same level. Unfortunately, the GNOME team is heavily understaffed a GNOME team member left at the beginning of the year for personal reasons, and the team now only has one semi-active member and me. Other An fvwm-nightshade spin is being worked on :-) . Apart from that, there are no teams maintaining other flavors in Tanglu. Security & Stable maintenance Thanks to several awesome people, the current Tanglu Stable release (Tanglu 3 Chromodoris ) receives regular updates, even for many packages which are not in the fully supported set. Tangluverse Tasks Tasks (not) done in the global Tanglu universe. HTTPS for community sites Thanks to our participation in the Let s Encrypt closed beta program, Tanglu websites like the user forums and bugtracker have been fully encrypted for a while, which should make submitting data to these sites much more secure. So far, we didn t encounter issues, which means that we will likely aim for getting HTTPS encryption enabled on every Tanglu website. Tanglu.org website The Tanglu main website didn t receive much love at all. It could use a facelift and more importantly updated content about Tanglu. So far, nobody volunteered to update the website, so this task is still open. It is, however, a high-priority task to increase our public visibility as a project, so updating the website is definitely something which will be done soon. Promotion It doesn t hurt to think about how to sell Tanglu as brand : What is Tanglu? Our motivation, our goals? What is our slogan? How can we communicate all of this to new users, without having them to read long explanations? (e.g. the Fedora Project has this nicely covered on their main website, and their slogan Freedom, Friends, Features, First immediately communicates the project s key values) Those are issues engineers don t think about often, still it is important to present Tanglu in a way that is easy to grasp for people hearing about it for the first time. So far, no people are working on this task specifically, although it regularly comes up on IRC. Sponsoring & Government Tanglu is by design not backed by any corporation. However, we still need to get our servers paid. Currently, Tanglu is supported by three sponsors, which basically provide the majority of our infrastructure. Also, developers provide additional machines to get Tanglu running and/or packages built. Still, this dependency on very few sponsors paying the majority of the costs is very bad, since it makes Tanglu vulnerable in case one sponsor decides to end sponsorship. We have no financial backing to be able to e.g. continue to pay an important server in case it s sponsor decides to drop sponsorship. Also, since Tanglu is no legal entity, accepting donations is hard for us at time, since a private person would need to accept the money on behalf of Tanglu. So we can t easily make donating to Tanglu possible (at least not in the way we want donations to be). These issues are currently being worked on, there are a couple of possible solutions on the table. I will write about details as soon as it makes sense to go public with them. In general, I am very happy with the Tanglu community: The developer community is a pleasure to work with, and interactions with our users on the forums or via the bugtracker are highly productive and friendly. Although the development speed has slowed down a bit, Tanglu is still an active and awesome project, and I am looking forward to the cool stuff we will do in future!

Antonio Terceiro: Bits from the Debian Continuous Integration project

It s been almost 2 years since the Debian Continuous Integration project has been launched, and it has proven to be a useful resource for the development of Debian. I have previously made a an introductory post, and this this is an update on the latest developments. Infrastructure upgrade Back in early 2014 when Debian CI was launched, there were less than 200 source packages with declared test suite metadata, and using a single worker machine polling the archive for updates and running tests sequentially in an infinite loop ( the simplest thing that could possibly work ) was OK-ish. Then our community started an incredible, slow and persistent effort to prepare source packages for automated testing, and we now have almost 5,000 of them. The original, over-simplistic design had to be replaced. The effort of transforming debci in a distributed system was started by Martin Pitt, who did an huge amount of work. In the latest months I was able to complete that work, to a point where I am confident in letting it run (mostly) unatended. We also had lots of contributions to the web UI from Brandon Fairchild, who was a GSOC intern in 2014, and continues to contribute to this date. All this work culminated in the migration from a single-worker model to a master/workers setup, currently with 10 worker nodes. On busy periods all of those worker nodes will go on for days with full utilization, but even then the turnaround between package upload and a test run is now a lot faster than it used to. Debian members can inspect the resource usage on those systems, as well as the length of the processing queue, by browsing to the corresponding munin instance (requires authentication via a SSL client certificated issued by sso.debian.org). The system is currenly being hosted on a Amazon EC2 account sponsored by Amazon. The setup is fully automated and reproducible. It is not fully (or at all) documented yet, but those interested should feel free to get in touch on IRC (OFTC, #debci) Testing backend changed from schroot to lxc Together with the infrastructure updates, we also switched to using lxc instead of schroot as backend. Most test suites should not be affected by this, but the default lxc settings might cause some very specific issues in a few packages. See for example #806542 ( liblinux-prctl-perl: autopkgtest failures: seccomp, capbset ) Adding support for KVM is also in the plans, and we will get to that at some point. Learn more If you want to learn more on how you can add tests for your package, a good first start is the debci online documentation (which is also available locally if you install debci ). You might also be interested in watching the live tutorial (WebM, 469 MB!) that has been presented at Debconf 15 earlier this year, full of tips and real examples from the archive. It would be awesome if someone wanted to transcribe that into a text tutorial ;-) How to get involved There are a few ways you can contribute: autodep8. if you are knowledgeable on a subset of packages that are very similar and can have their tests executed in a similar way, such as $Language libraries , you might consider writing a test metadata generator so that each package does not need to declare a debian/tests/control file explicitly, requiring only The Testsuite: header in debian/control. Ruby and Perl are already covered, and there is initial support for NodeJS. Adding support for new types of packages is very easy. See the source repository. If you manage to add support for your favorite language, please get in touch so we can discuss whitelisting the relavant packages in ci.debian.net so that they will get their tests executed even before being uploaded with the proper Testsuite: control field. autopkgtest. autopkgtest is responsible for actually running your tests, and you can use it to reproduce test runs locally. debci. debci is the system running in ci.debian.net (version 1.0, currently in testing, is exactly what is running up there, minus a version number and a changelog entry). It can also be used to have private clones of ci.debian.net, e.g. for derivatives or internal Debian-related development. See for example the Ubuntu autopkgtest site. Getting in touch For maintainer queries and general discussion: For the development of debci/autopkgtest/autodep8

Lunar: Reproducible builds: week 32 in Stretch cycle

The first reproducible world summit was held in Athens, Greece, from December 1st-3rd with the support of the Linux Foundation, the Open Tech Fund, and Google. Faidon Liambotis has been an amazing help to sort out all local details. People at ImpactHub Athens have been perfect hosts. North of Athens from the Acropolis with ImpactHub in the center Nearly 40 participants from 14 different free software project had very busy days sharing knowledge, building understanding, and producing actual patches. Anyone interested in cross project discussions should join the rb-general mailing-list. What follows focuses mostly on what happened for Debian this previous week. A more detailed report about the summit will follow soon. You can also read the ones from Joachim Breitner from Debian, Clemens Lang from MacPorts, Georg Koppen from Tor, Dhiru Kholia from Fedora, and Ludovic Court s wrote one for Guix and for the GNU project. The Acropolis from Infrastructure Several discussions at the meeting helped refine a shared understanding of what kind of information should be recorded on a build, and how they could be used. Daniel Kahn Gillmor sent a detailed update on how .buildinfo files should become part of the Debian archive. Some key changes compared to what we had in mind at DebConf15: Hopefully, ftpmasters will be able to comment on the updated proposal soon. Packages fixed The following packages have become reproducible due to changes in their build dependencies: fades, triplane, caml-crush, globus-authz. The following packages became reproducible after getting fixed: Some uploads fixed some reproducibility issues, but not all of them: Patches submitted which have not made their way to the archive yet: akira sent proposals on how to make bash reproducible. Alexander Couzens submitted a patch upstream to add support for SOURCE_DATE_EPOCH in grub image generator (#787795). reproducible.debian.net An issue with some armhf build nodes was tracked down to a bad interaction between uname26 personality and new glibc (Vagrant Cascadian). A Debian package was created for koji, the RPM building and tracking system used by Fedora amongst others. It is currently waiting for review in the NEW queue. (Ximin Luo, Marek Marczykowski-G recki) diffoscope development diffoscope now has a dedicated mailing list to better accommodate its growing user and developer base. Going through diffoscope's guts together enabled several new contributors. Baptiste Daroussin, Ed Maste, Clemens Lang, Mike McQuaid, Joachim Breitner all contributed their first patches to improve portability or add new features. Regular contributors Chris Lamb, Reiner Herrmann, and Levente Polyak also submitted improvements. diffoscope hacking session in Athens The next release should support more operating systems, filesystem image comparison via libguestfs, HTML reports with on-demand loading, and parallel processing for the most noticeable improvements. Package reviews 27 reviews have been removed, 17 added and 14 updated in the previous week. Chris Lamb and Val Lorentz filed 4 new FTBFS reports. Misc. Baptiste Daroussin has started to implement support for SOURCE_DATE_EPOCH in FreeBSD in libpkg and the ports tree. Thanks Joachim Breitner and h01ger for the pictures.

Ben Hutchings: Debian LTS work, November 2015

I've now been working on Debian LTS for a full year, so I'm going to stop counting months. In November, I carried over 5 hours from October and was assigned another 15 hours of work by Freexian's Debian LTS initiative. However, I spent much of the month on sick leave, so I only worked 5 billable hours on Debian LTS plus some unbilled time while on leave. I had another week in the front desk role, and triaged about 20 new issues. Less than half actually affected packages supported in squeeze-lts, and only about 5 were important. CVE-2015-5309 in putty had a patch that was fairly easy to backport, so I did that, uploaded and sent DLA 347-1. I backported several security fixes to linux-2.6 and sent some of those we had already released to Willy Tarreau for inclusion in Linux 2.6.32-longterm. At the end of the month, I reviewed Linux 2.6.32.69-rc1 and found a couple of bugs, leading to an -rc2. I applied that to the linux-2.6 packaging branch for squeeze-lts and spent a little time testing it, thankfully not hitting any regressions.

10 December 2015

Dmitry Shachnev: Magic infinite sequences for Python

Today I have released a small module for Python 3 that implements cached lazy infinite sequences. Here are some examples that demonstrate what this module can do: 
>>> InfSequence(5, 6, ...)
<InfSequence: 5 6 7 8 9 10 ...>
>>> InfSequence.geometric_progression(9)
<InfSequence: 1 9 81 729 6561 59049 ...>
>>> InfSequence.cycle('foo', 'bar')
<InfSequence: 'foo' 'bar' 'foo' 'bar' 'foo' 'bar' ...>
>>> InfSequence.fibonacci()
<InfSequence: 0 1 1 2 3 5 ...>
Slicing works: 
>>> InfSequence(5, 6, ...)[5:]
<InfSequence: 10 11 12 13 14 15 ...>
>>> InfSequence(5, 6, ...)[5::2]
<InfSequence: 10 12 14 16 18 20 ...>
A somewhat reverse operation: 
>>> (2, 3, 4) + InfSequence(5, 6, ...)
<InfSequence: 2 3 4 5 6 7 ...>
Various arithmetic operations are supported: 
>>> InfSequence(1, 2, ...) ** 2
<InfSequence: 1 4 9 16 25 36 ...>
>>> InfSequence(3, 5, ...) - InfSequence(1, 2, ...)
<InfSequence: 2 3 4 5 6 7 ...>
>>> InfSequence(1, 2, ...).partial_sum(10)
55
More magic methods: 
>>> InfSequence(1, 2, ...).accumulate()
<InfSequence: 1 3 6 10 15 21 ...>
>>> InfSequence(0, 2, ...) @ InfSequence(1)
<InfSequence: 1 4 9 16 25 36 ...>
For the complete API overview, please look at the documentation. You can install the module from PyPI. It is licensed under 3-clause BSD license. The source code is available on GitHub.

Dmitry Shachnev: Magic infinite sequences for Python

Today I have released a small module for Python 3 that implements cached lazy infinite sequences. Here are some examples that demonstrate what this module can do: 
>>> InfSequence(5, 6, ...)
<InfSequence: 5 6 7 8 9 10 ...>
>>> InfSequence.geometric_progression(9)
<InfSequence: 1 9 81 729 6561 59049 ...>
>>> InfSequence.cycle('foo', 'bar')
<InfSequence: 'foo' 'bar' 'foo' 'bar' 'foo' 'bar' ...>
>>> InfSequence.fibonacci()
<InfSequence: 0 1 1 2 3 5 ...>
Slicing works: 
>>> InfSequence(5, 6, ...)[5:]
<InfSequence: 10 11 12 13 14 15 ...>
>>> InfSequence(5, 6, ...)[5::2]
<InfSequence: 10 12 14 16 18 20 ...>
A somewhat reverse operation: 
>>> (2, 3, 4) + InfSequence(5, 6, ...)
<InfSequence: 2 3 4 5 6 7 ...>
Various arithmetic operations are supported: 
>>> InfSequence(1, 2, ...) ** 2
<InfSequence: 1 4 9 16 25 36 ...>
>>> InfSequence(3, 5, ...) - InfSequence(1, 2, ...)
<InfSequence: 2 3 4 5 6 7 ...>
>>> InfSequence(1, 2, ...).partial_sum(10)
55
More magic methods: 
>>> InfSequence(1, 2, ...).accumulate()
<InfSequence: 1 3 6 10 15 21 ...>
>>> InfSequence(0, 2, ...) @ InfSequence(1)
<InfSequence: 1 4 9 16 25 36 ...>
For the complete API overview, please look at the documentation. You can install the module from PyPI. It is licensed under 3-clause BSD license. The source code is available on GitHub.

James McCoy: filtering-packaging-mails

I had been meaning to post about filtering package related emails for awhile now. Initially, it was going to be to spread the word about the under documented List-ID headers, which are useful when you don't have the ability to filter on arbitrary headers. The recent transition of such mails from the PTS to Debian's instance of Distro Tracker reminded me about this, and some info on how to transition current filtering may be useful for more than just me. Old PTS emails Mails sent via the PTS contained a few headers to aid filtering. There were various old keywords, but here are some of the ones I found useful:
bts
Normal bug tracking traffic
bts-control
Notifications from control@bugs.debian.org
buildd
Build failures
contact
Mails to $srcpackage@packages.debian.org
cvs
Version control notifications
upload-binary
Binary package uploads
upload-source
Source package uploads
New Distro Tracker emails The mails sent by Distro Tracker have a different set of headers. The set of new keywords are almost the same, but a few changes have been made.

9 December 2015

Daniel Pocock: Is WebRTC one of your goals for 2016?

WebRTC continues to gather momentum around the world. Over the next week, Paris will host a TADHack event on WebRTC (12-13 December) followed by Europe's most well known meeting of the WebRTC community, the annual WebRTC Conference and Expo, 16-18 December. 2015 has been a busy year for WebRTC developers, in the browser, on the server-side and even in documentation, with the online publication of The RTC Quick Start Guide. These efforts have all come together to create a stable foundation for many implementations in 2016. Demo The JSCommunicator demo video shows just how convenient WebRTC can be, looking at the first customer-facing WebRTC deployment on Wall Street, a project I put together back in 2014: This solution was implemented entirely with free, open source software integrated with a traditional corporate PBX. The project involved significant innovation to bring together a new technology like WebRTC with a very established corporate telephony infrastructure. For example, the solution makes use of the reSIProcate Python scripting to add the Avaya UUI headers to the SIP signaling, so it can integrate seamlessly with all existing Avaya customizations and desktop CRM software. Is this something you can imagine on your organization's web site or as part of your web-based product or service? DruCall module for Drupal - WebRTC without coding If you run a Drupal CMS or if you would like to, the DruCall module provides a very quick way to get started with WebRTC. On a Debian or Ubuntu server, you can automatically deploy the entire Drupal stack, Apache, MySQL and all module dependencies with $ sudo apt-get install -t jessie-backports drupal7-mod-drucall JSCommunicator, the generic SIP phone for web pages If you don't want to do any JavaScript development, JSCommunicator may be the way to go. JSCommunicator is a completely generic solution that can be completely re-branded just by tweaking the HTML and CSS. All phone features can be enabled and disabled using the configuration file. WebRTC plugins for CRM solutions As part of Google Summer of Code 2014, Juliana Louback created a WebRTC plugin for the xTuple enterprise CRM and ERP suite. The source code of the DruCall and xTuple plugins provide an excellent point of reference for developing similar plugins for other web applications. Both of them are based on JSCommunicator which is designed to embed easily into any existing HTML page or templating system. Get involved To find out more and discuss RTC using free software and open standards, please join us on the Free-RTC mailing list.

Vincent Fourmond: Announcing QSoas, a powerful y=f(x) data analysis software

Why a new data analysis software ?I'm a researcher at the interface between physics, chemistry and biology, and in our team, we pride ourselves on making the most of the data we acquire, especially through quantitative analysis and modelling. In fact, we spend a lot of time doing fitting simple formulas or complex differential equations to our data. As we were not really satisfied with the data fitting capacities of the software available, we've had our custom data processing/fitting tool, SOAS, for ages. However, that tool was hard to maintain (Fortran + Fortran libraries interfacing with X11 with ABI changing every once in a while without notice), impossible to port to non-X11 platforms, not very user-friendly, and not easy to extend at all. So, when I got my permanent position, a rewrote a completely new version from scratch, called QSoas using C++, Qt, Ruby and the GNU Scientific Library. The result is incomparably more powerful, more easy to maintain, more user-friendly, and more portable (I build it for Linux, Mac and Windows).
What does it do ?The main features of QSoas are:
What has it done already ?We've relied heavily on QSoas's functionalities for the past 3-4 years, and a great part of the team's publications just wouldn't be there without QSoas. More precisely on selected examples:
I hope it will also help you get more than you previously could from your data (and faster, too !).
I want it, where can I get it ?You can download QSoas version 1.0 on its website. The source code is fully available under the GNU General Public License. For those not too compilation-savvy, we sell pre-built binaries for windows and mac, in collaboration with Satt Sud-Est and eValorix. Compilation under Linux is very simple, but I'm willing to come up with a Debian package, should some of you want that. You should definitely have a look at the tutorial and the command reference.

Guido G nther: Running ansible's integration tests

ansible is a great tool for deployments. While it doesn't ship that many unit tests it comes with heaps of integration tests that can be run using: 
git submodule update --init
. hacking/env-setup
cd tests/integration
make
after cloning the repo from here. However when working on individual parts one often only wants to test a single role. This can be done via: 
git submodule update --init
. hacking/env-setup
cd tests/integration
ansible-playbook -e @integration_config.yml -i"testhost," -c local test_filters.yml
when e.g. working on some new filers. Just putting it here since I just found myself digging this out the second time.

8 December 2015

Daniel Pocock: Comparison of free, open source accounting software

There are a diverse range of free software solutions for accounting. Personally, I have been tracking my personal and business accounts using a double-entry accounting system since I started doing freelance work about the same time I started university. Once you become familiar with double-entry accounting (which doesn't require much more than basic arithmetic skills and remembering the distinction between a debit and a credit) it is unlikely you would ever want to go back to a spreadsheet. Accounting software promoted for personal/home users often provides a very basic ledger where you can distinguish how much cash goes to rent, how much to food and how much to the tax man. Software promoted for business goes beyond the core ledger functionality and provides helpful ways to keep track of which bills you already paid, which are due imminently and which customers haven't paid you. Even for a one-man-band, freelancer or contractor, using a solution like this is hugely more productive than trying to track bills in a spreadsheet. Factors to consider when choosing a solution Changing accounting software can be a time consuming process and require all the users to learn a lot of new things. Therefore, it is generally recommended to start with something a little more powerful than what you need in the hope that you will be able to stick with it for a long time. With proprietary software this can be difficult because the more advanced solutions cost more money than you might be willing to pay right now. With free software, there is no such limitation and you can start with an enterprise-grade solution from day one and just turn off or ignore the features you don't need yet. If you are working as an IT consultant or freelancer and advising other businesses then it is also worthwhile to choose a solution for yourself that you can potentially recommend to your clients and customize for them. The comparison Here is a quick comparison of some of the free software accounting solutions that are packaged on popular Linux distributions like Debian, Ubuntu and Fedora:
Product Postbooks Tryton GnuCash LedgerSMB HomeBank Skrooge KMyMoney BG Financas Grisbi
GUI Y Y Y N Y Y Y Y Y
Web UI Y Y N Y N N N N N
Multi-user Y Y N Y N N N N Y
File storage N Y Y N Y Y Y N N
SQL storage Y Y Y Y N N Y Y Y
Multi-currency Y Y Y Y N Y Y Y
A/R Y Y Y Y N Y Y Y
A/P Y Y Y Y N Y Y Y
VAT/GST Y Y Y Y N N Y Y
Inventory Y Y N Y N N N
Linux Y Y Y Y Y Y Y Y Y
Windows Y Y
Mac OS Y Y
Technology C++, JavaScript, Node Python C Perl C Java
License CPAL GPL3 GPL2 GPL2
The table doesn't consider Odoo (formerly OpenERP) because the packages were considered buggy and are not maintained any more, it is replaced by Tryton. Compiere and Adempiere are other well known solutions but they haven't been packaged at all. Features in detail While the above list gives a basic summary of features, it is necessary to look more closely at how they are implemented. For example, if you need to report on VAT or GST, there are two methods of reporting: cash or accrual. Some products only support accruals because that is easier to implement. Even in commercial products that support cash-based VAT reporting, the reports are not always accurate (I've seen that problem with the proprietary Quickbooks software) and a tax auditor will be quick to spot such errors. The only real way to get to know one of these products is to test it for a couple of hours. Postbooks, for example, provides the Demo database so you can test it with dummy data without making any real commitment. User interface choices If you need to support users on multiple platforms or remote users such as an accountant or book-keeper, it is tempting to choose a solution with a web interface. The solutions with desktop interfaces can be provisioned to remote users using a terminal-server setup. The full GUI solutions tend to offer a richer user interface and reporting experience. It can frequently be useful to have multiple windows or reports open at the same time, doing this with browser tabs can be painful. File or database storage There are many good reasons to use database storage and my personal preference is for PostgreSQL. Using a database allows you to run a variety of third-party reporting tools and write your own scripts for data import and migration. Community and commercial support When dealing with business software, it is important to look at both the community and the commercial support offerings that are available. Some communities have events, such as xTupleCon for Postbooks or a presence at other major events like FOSDEM. Summary My personal choice at the moment is Postbooks from xTuple. This is because of a range of factors, including the availability of both web and desktop clients, true multi-user support, the multi-currency support and the PostgreSQL back-end.

Mark Brown: Maximising the efficiency of chained regulators

Linux v4.4 will include a cool new feature contributed by Sascha Hauer of Pengutronix which propagates voltages set on a regulator to the regulators that supply it (taking into account the minimum headroom that the child regulator needs). The original reason for implementing it was to allow us to set voltages through simple unregulated power switches but the cool bit is that we can also use this to save power in some systems. There are two standard types of voltage regulator, DCDCs which are very efficient but produce noisy output and LDOs which are much less efficient but a lot cheaper and simpler and produce much cleaner output. What a lot of systems do to avoid a lot of the inefficiency of LDOs is to use a DCDC to reduce the voltage from the main system power supply (eg, the battery) to something close to the minimum power supply for the LDOs in the system This means that most of the voltage reduction (which is what generates inefficiency) comes from the DCDC rather than the LDO but you still get the clean power supply from the LDO and can have several different output voltages from a single expensive DCDC. By managing the voltage we set on the DCDC at runtime depending on the LDO configurations we can maximise the power savings from this setup, putting as much of the work onto the DCDC as we can at any given moment. This has been at the back of my mind for a long time, I m really pleased to see it implemented. It s a pretty small change code wise and probably not worth implementing for any one system but when we do it in the core like this hopefully many systems will be able to use it and the effects will add up.

Vincent Sanders: I said it was wired like a Christmas tree

I have recently acquired a 27U high 19 inch rack in which I hope to consolidate all the computing systems in my home that do not interact well with humans.

My main issue is that modern systems are just plain noisy, often with multiple small fans whining away. I have worked to reduce this noise by using quieter components as replacements but in the end it is simply better to be able to put these systems in a box out of the way.

The rack was generously given to me by Andy Simpkins and aside from being a little dirty having been stored for some time was in excellent condition. While the proverbs "never look a gift horse in the mouth" and "beggars cannot be choosers" are very firmly at the front of my mind there were a few minor obstacles to overcome to make it fit in its new role with a very small budget.

The new home for the rack was to be a space under the stairs where, after careful measurement, I determined it would just fit. After an hour or two attempting to manoeuvre a very heavy chunk of steel into place I determined it was simply not possible while it was assembled. So I ended up disassembling and rebuilding the whole rack in a confined space.

The rack is 800mm wide IMRAK 1400 rather than the more common 600mm width which means it employs "cable reducing channels" to allow the mounting of standard width rack units. Most racks these days come with four posts in the corners to allow for longer kit to be supported front and back. This particular rack was not fitted with the rear posts and a brief call to the supplier indicated that any spares from them would be eyewateringly expensive (almost twice the cost of purchasing a new rack from a different supplier) so I had to get creative.

Shelves that did not require the rear rails were relatively straightforward and I bought two 500mm deep cantilever type from Orion (I have no affiliation with them beyond being a satisfied customer).

I took a trip to the local hardware store and purchased some angle brackets and 16mm steel square tube. From this I made support rails which means the racked kit has support to its rear rather than relying solely on being supported by its rack ears.

The next problem was the huge hole in the bottom of the rack where I was hoping to put the UPS and power switching. This hole is intended for use with raised flooring where cables enter from below, when not required it is filled in with a "bottom gland plate". Once again the correct spares for the unit were not within my budget.

Around a year ago I built several systems for open source projects from parts generously donated by Mythic Beasts (yes I did recycle servers used to build a fort). I still had some leftover casework from one of those servers so ten minutes with an angle grinder and a drill and I made myself a suitable plate.

The final problem I faced is that it is pretty dark under the stairs and while putting kit in the rack I could not see what I was doing. After some brief Googling I decided that all real rack lighting solutions were pretty expensive and not terribly effective.

At this point I was interrupted by my youngest son trying to assemble the Christmas tree and the traditional "none of the lights work" so we went off to the local supermarket to buy some bulbs. Instead we bought a 240 LED string for 10 (15usd) in the vague hope that next year they will not be broken.

I immediately had a light bulb moment and thought how a large number of efficient LED bulbs at a low price would be ideal for lighting a rack. So my rack is indeed both wired like and as a Christmas tree!

Now I just have to finish putting all the systems in there and I will be able to call the project a success.

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