Search Results: "ed"

23 April 2020

Evgeni Golov: Controlling roller shutters using a Shelly 2.5, ESPHome and Home Assistant

Our house has roller shutters on all windows and most of them have an electric motor to open and close them. The motors are Schellenberg shaft motors (not sure this is the right English term), that you can configure end positions for and then by applying current to the right pair of pins they move the shutters up and down until the current is removed or one of the endstops is reached. As the motors were installed over a long period of time, the attached control units varied in functionality: different ways to program open/close times, with and without battery for the clock/settings etc, but they all had something in common: no central management and pretty ugly. We decided to replace those control units with regular 2 gang light switches that match the other switches in the house. And as we didn't want to lose the automatic open/close timer, we had to add some smarts to it. Shelly 2.5 and ESPHome Say hello to Shelly 2.5! The Shelly 2.5 is an ESP8266 with two relays attached to it in a super tiny package you can hide in the wall behind a regular switch. Pretty nifty. It originally comes with a Mongoose OS based firmware and an own app, but ain't nobody needs that, especially nobody who wants to implement some crude logic. That said, the original firmware isn't bad. It has a no-cloud mode, a REST API and does support MQTT for integration into Home Assistant and others. My ESP firmware of choice is ESPHome, which you can flash easily onto a Shelly (no matter 1, 2 or 2.5) using a USB TTL adapter that provides 3.3V. Home Assistant has native ESPHome support with auto-discovery, which is much nicer than manually attaching things to MQTT topics. To get ESPHome compiled for the Shelly 2.5, we'll need a basic configuration like this:
esphome:
  name: shelly25
  platform: ESP8266
  board: modwifi
  arduino_version: 2.4.2
We're using board: modwifi as the Shelly 2.5 (and all other Shellys) has 2MB flash and the usually recommended esp01_1m would only use 1MB of that - otherwise the configurations are identical (see the PlatformIO entries for modwifi and esp01_1m). And arduino_version: 2.4.2 is what the Internet suggests is the most stable SDK version, and who will argue with the Internet?! Now an ESP8266 without network connection is boring, so we add a WiFi configuration:
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  power_save_mode: none
The !secret commands load the named variables from secrets.yaml. While testing, I found the network connection of the Shelly very unreliable, especially when placed inside the wall and thus having rather bad bad reception (-75dBm according to ESPHome). However, setting power_save_mode: none explicitly seems to have fixed this, even if NONE is supposed to be the default on ESP8266. At this point the Shelly has a working firmware and WiFi, but does not expose any of its features: no switches, no relays, no power meters. To fix that we first need to find out the GPIO pins all these are connected to. Thankfully we can basically copy paste the definition from the Tasmota (another open-source firmware for ESPs) template:
pin_led1: GPIO0
pin_button1: GPIO2
pin_relay1: GPIO4
pin_switch2n: GPIO5
pin_sda: GPIO12
pin_switch1n: GPIO13
pin_scl: GPIO14
pin_relay2: GPIO15
pin_ade7953: GPIO16
pin_temp: A0
If we place that into the substitutions section of the ESPHome config, we can use the names everywhere and don't have to remember the pin numbers. The configuration for the ADE7953 power sensor and the NTC temperature sensor are taken verbatim from the ESPHome documentation, so there is no need to repeat them here. The configuration for the switches and relays are also rather straight forward:
binary_sensor:
  - platform: gpio
    pin: $ pin_switch1n 
    name: "Switch #1"
    internal: true
    id: switch1
  - platform: gpio
    pin: $ pin_switch2n 
    name: "Switch #2"
    internal: true
    id: switch2
switch:
  - platform: gpio
    pin: $ pin_relay1 
    name: "Relay #1"
    internal: true
    id: relay1
    interlock: &interlock_group [relay1, relay2]
  - platform: gpio
    pin: $ pin_relay2 
    name: "Relay #2"
    internal: true
    id: relay2
    interlock: *interlock_group
All marked as internal: true, as we don't need them visible in Home Assistant. ESPHome and Schellenberg roller shutters Now that we have a working Shelly 2.5 with ESPHome, how do we control Schellenberg (and other) roller shutters with it? Well, first of all we need to connect the Up and Down wires of the shutter motor to the two relays of the Shelly. And if they would not be marked as internal: true, they would show up in Home Assistant and we would be able to flip them on and off, moving the shutters. But this would also mean that we need to flip them off each time after use, as while the motor knows when to stop and will do so, applying current to both wires at the same time produces rather interesting results. So instead of fiddling around with the relays directly, we define a time-based cover in our configuration:
cover:
  - platform: time_based
    name: "$ location  Rolladen"
    id: rolladen
    open_action:
      - switch.turn_on: relay2
    open_duration: $ open_duration 
    close_action:
      - switch.turn_on: relay1
    close_duration: $ close_duration 
    stop_action:
      - switch.turn_off: relay1
      - switch.turn_off: relay2
We use a time-based cover because that's the easiest thing that will also turn the relays off for us after the shutters have been opened/closed, as the motor does not "report" any state back. We could use the integrated power meter of the Shelly to turn off when the load falls under a threshold, but I was too lazy and this works just fine as it is. Next, let's add the physical switches to it. We could just add on_press automations to the binary GPIO sensors we configured for the two switch inputs the Shelly has. But if you have kids at home, you'll know that they like to press ALL THE THINGS and what could be better than a small kill-switch against small fingers?
switch:
  [ previous definitions go here ]
  - platform: template
    id: block_control
    name: "$ location  Block Control"
    optimistic: true
  - platform: template
    name: "Move UP"
    internal: true
    lambda:  -
      if (id(switch1).state && !id(block_control).state)  
        return true;
        else  
        return false;
       
    on_turn_on:
      then:
        cover.open: rolladen
    on_turn_off:
      then:
        cover.stop: rolladen
  - platform: template
    name: "Move DOWN"
    internal: true
    lambda:  -
      if (id(switch2).state && !id(block_control).state)  
        return true;
        else  
        return false;
       
    on_turn_on:
      then:
        cover.close: rolladen
    on_turn_off:
      then:
        cover.stop: rolladen
This adds three more template switches. The first one, "Block Control", is exposed to Home Assistant, has no lambda definition and is set to optimistic: true, which makes is basically a dumb switch that can be flipped at will and the only thing it does is storing the binary on/off state. The two others are almost identical. The name differs, obviously, and so does the on_turn_on automation (one triggers the cover to open, the other to close). And the really interesting part is the lambda that monitors one of the physical switches and if that is turned on, plus "Block Control" is off, reports the switch as turned on, thus triggering the automation. With this we can now block the physical switches via Home Assistant, while still being able to control the shutters via the same. All this (and a bit more) can be found in my esphome-configs repository on GitHub, enjoy!

Mike Hommey: Announcing git-cinnabar 0.5.5

Please partake in the git-cinnabar survey. Git-cinnabar is a git remote helper to interact with mercurial repositories. It allows to clone, pull and push from/to mercurial remote repositories, using git. Get it on github. These release notes are also available on the git-cinnabar wiki. What s new since 0.5.4?

22 April 2020

Anisa Kuci: Salsa username update

Debian salsa now allows usernames without the -guest suffix for everyone. The Debian GitLab instance, salsa, used to append -guest to every username that was not a Debian Developer (DD). This has recently been changed and every user can register any available username now. Existing usernames can also be renamed:
  1. Go to your account settings
  2. Change the username in the Change Username section
  3. Click Update username
Please make sure to also update your bookmarks and pages you have linked your Debian salsa profile. You can find me now as anisa. Stay safe and happy hacking!

Jonathan Dowland: SUPERHOT

Continuing a series of blog posts about casual Nintendo Switch games, next in the series is SUPERHOT. Normally 19.99, I picked it up for 13.99 in a sale. That's a little bit more than I would usually pay for a casual game. SUPERHOT first came on my radar because someone I know from a baby group worked on their VR port in some capacity.
Slow-motion buckshot Slow-motion buckshot
A first-person shooter, SUPERHOT's USP is that time only progresses when you move well, nearly. Time is slowed to a complete crawl when you are not moving. The game's visual style is very distinctive: Almost everything is a washed out grey or white colour and porcelean-like texture, except weapons and objects you can interact with, which are a matt black, and enemies, which are a bright red. It reminds me a lot of the 1992 Amiga game Robocop 3.
Robocop 3 Robocop 3
The play-style is very reminiscent of the "Bullet Time" sequences in The Matrix seemingly impossibly overwhelming odds deftly manoeuvred through thanks to superhuman reaction times. The game has a relatively short campaign of little vignettes, linked together by a cyberpunk narrative. The game is sometimes criticised for the short campaign, but for me that's ideal. And the vignettes being short and quite standalone suits my play requirements very well.
Amiga easter-egg Amiga easter-egg
The narrative interspersed between the play scenarios is a little bit over-long, and you can spend an unreasonable amount of time bashing buttons to get through it. Despite that it's a moderately interesting story. Once you've beaten the campaign, you can go back and play any of the scenarios again, or try the newly unlocked endless mode. I haven't tried that yet. The original prototype for the game is a free-to-play in-browser demo, available here. On Windows PC, there's a sequel-of-sorts in the works called MIND CONTROL DELETE with a lot of new features to add replay value.

21 April 2020

Matthew Garrett: Linux kernel lockdown, integrity, and confidentiality

The Linux kernel lockdown patches were merged into the 5.4 kernel last year, which means they're now part of multiple distributions. For me this was a 7-year journey, which means it's easy to forget that others aren't as invested in the code as I am. Here's what these patches are intended to achieve, why they're implemented in the current form and what people should take into account when deploying the feature.

Root is a user - a privileged user, but nevertheless a user. Root is not identical to the kernel. Processes running as root still can't dereference addresses that belong to the kernel, are still subject to the whims of the scheduler and so on. But historically that boundary has been very porous. Various interfaces make it straightforward for root to modify kernel code (such as loading modules or using /dev/mem), while others make it less straightforward (being able to load new ACPI tables that can cause the ACPI interpreter to overwrite the kernel, for instance). In the past that wasn't seen as a significant issue, since there were no widely deployed mechanisms for verifying the integrity of the kernel in the first place. But once UEFI secure boot became widely deployed, this was a problem. If you verify your boot chain but allow root to modify that kernel, the benefits of the verified boot chain are significantly reduced. Even if root can't modify the on-disk kernel, root can just hot-patch the kernel and then make this persistent by dropping a binary that repeats the process on system boot.

Lockdown is intended as a mechanism to avoid that, by providing an optional policy that closes off interfaces that allow root to modify the kernel. This was the sole purpose of the original implementation, which maps to the "integrity" mode that's present in the current implementation. Kernels that boot in lockdown integrity mode prevent even root from using these interfaces, increasing assurances that the running kernel corresponds to the booted kernel. But lockdown's functionality has been extended since then. There are some use cases where preventing root from being able to modify the kernel isn't enough - the kernel may hold secret information that even root shouldn't be permitted to see (such as the EVM signing key that can be used to prevent offline file modification), and the integrity mode doesn't prevent that. This is where lockdown's confidentiality mode comes in. Confidentiality mode is a superset of integrity mode, with additional restrictions on root's ability to use features that would allow the inspection of any kernel memory that could contain secrets.

Unfortunately right now we don't have strong mechanisms for marking which bits of kernel memory contain secrets, so in order to achieve that we end up blocking access to all kernel memory. Unsurprisingly, this compromises people's ability to inspect the kernel for entirely legitimate reasons, such as using the various mechanisms that allow tracing and probing of the kernel.

How can we solve this? There's a few ways:
  1. Introduce a mechanism to tag memory containing secrets, and only restrict accesses to this. I've tried to do something similar for userland and it turns out to be hard, but this is probably the best long-term solution.
  2. Add support for privileged applications with an appropriate signature that implement policy on the userland side. This is actually possible already, though not straightforward. Lockdown is implemented in the LSM layer, which means the policy can be imposed using any other existing LSM. As an example, we could use SELinux to impose the confidentiality restrictions on most processes but permit processes with a specific SELinux context to use them, and then use EVM to ensure that any process running in that context has a legitimate signature. This is quite a few hoops for a general purpose distribution to jump through.
  3. Don't use confidentiality mode in general purpose distributions. The attacks it protects against are mostly against special-purpose use cases, and they can enable it themselves.

My recommendation is for (3), and I'd encourage general purpose distributions that enable lockdown to do so only in integrity mode rather than confidentiality mode. The cost of confidentiality mode is just too high compared to the benefits it provides. People who need confidentiality mode probably already know that they do, and should be in a position to enable it themselves and handle the consequences.

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Debian Project Leader: Bits from the new DPL

My fellow Debianites, It's been one month, one week and one day since I decided to run for this DPL term. The Debian community has been through a variety of interesting times during the last decade, and instead of focusing on grand, sweeping changes for Debian, core to my DPL campaign was to establish a sense of normality and stability so that we can work on community building, continue to focus on technical excellence and serve our users the best we can. Thing don't always work out as we plan, and for many of us, Debian recently had to take a back seat to personal priorities. Back when I posted my intention to run, there were 125 260 confirmed cases of COVID-19 globally. Today, that number is 20 times higher, with the actual infected number likely to be significantly higher. A large number of us are under lock-down, where we not only fear the disease and its effect on local hospitals and how it will affect our loved ones, but also our very livelihoods and the future of our local businesses and industry. I don't mean to be gloomy with the statement above, I am after all, an optimist - but unfortunately it does get even worse. Governments and corporations around the world have started to take advantage of COVID-19 in negative ways and are making large sweeping changes that undermine the privacy and rights of individuals everywhere. For many reasons, including those above, I believe that the Debian project is more important and relevant now than it's ever been before. The world needs a free, general purpose operating system, unburdened by the needs of profit, which puts the needs of its users first, providing a safe and secure platform for the computing needs of the masses. While we can't control or fix all the problems in the world, we can control our response to it, and be part of the solutions that bring the change we want to see. During my term as DPL, I will be available to help with problems in our community to the maximum extent that my time permits. If we help ourselves, we will be in a better position to help others. If you (or your team) get stuck and are in need of help, then please do not hessitate to e-mail me. A few thank-yous As incoming DPL, I'd like to thank Sam Hartman on behalf of the project for the work that he's done over the last year as DPL. It's a tremendous time commitment that requires constant attention to detail. On Sunday, Sam and I had a handover meeting where we discussed various DPL responsibilities including finances, delegations (including specifics of some delegations), legal matters, outreach and other questions I had. I'd also like to thank Sam for taking the time to do this. Thank you to Sruthi Chadran and Brian Gupta who took the time to also run for DPL this year. Both candidates brought important issues to the forefront and I hope to work with both of them on those in the near future. DPL Blog Today, I've started a new blog for the Debian Project Leader to help facilitate more frequent communication, and to reach a wider audience via Planet Debian. This will contain supplemental information to what I send to the debian-devel-announce mailing list. Want to help? In my platform, I listed some key areas that I'd like to work on. My work won't be limited to those, but it should give you some idea of the type of DPL that I'll be. If you'd like to get involved, feel free to join the #debian-dpl channel on the oftc IRC network, and please introduce yourself along with any areas of interest that you'd like to contribute to.

Debian Project Leader: Bits from the new DPL

My fellow Debianites, It's been one month, one week and one day since I decided to run for this DPL term. The Debian community has been through a variety of interesting times during the last decade, and instead of focusing on grand, sweeping changes for Debian, core to my DPL campaign was to establish a sense of normality and stability so that we can work on community building, continue to focus on technical excellence and serve our users the best we can. Thing don't always work out as we plan, and for many of us, Debian recently had to take a back seat to personal priorities. Back when I posted my intention to run, there were 125 260 confirmed cases of COVID-19 globally. Today, that number is 20 times higher, with the actual infected number likely to be significantly higher. A large number of us are under lock-down, where we not only fear the disease and its effect on local hospitals and how it will affect our loved ones, but also our very livelihoods and the future of our local businesses and industry. I don't mean to be gloomy with the statement above, I am after all, an optimist - but unfortunately it does get even worse. Governments and corporations around the world have started to take advantage of COVID-19 in negative ways and are making large sweeping changes that undermine the privacy and rights of individuals everywhere. For many reasons, including those above, I believe that the Debian project is more important and relevant now than it's ever been before. The world needs a free, general purpose operating system, unburdened by the needs of profit, which puts the needs of its users first, providing a safe and secure platform for the computing needs of the masses. While we can't control or fix all the problems in the world, we can control our response to it, and be part of the solutions that bring the change we want to see. During my term as DPL, I will be available to help with problems in our community to the maximum extent that my time permits. If we help ourselves, we will be in a better position to help others. If you (or your team) get stuck and are in need of help, then please do not hessitate to e-mail me. A few thank-yous As incoming DPL, I'd like to thank Sam Hartman on behalf of the project for the work that he's done over the last year as DPL. It's a tremendous time commitment that requires constant attention to detail. On Sunday, Sam and I had a handover meeting where we discussed various DPL responsibilities including finances, delegations (including specifics of some delegations), legal matters, outreach and other questions I had. I'd also like to thank Sam for taking the time to do this. Thank you to Sruthi Chadran and Brian Gupta who took the time to also run for DPL this year. Both candidates brought important issues to the forefront and I hope to work with both of them on those in the near future. DPL Blog Today, I've started a new blog for the Debian Project Leader to help facilitate more frequent communication, and to reach a wider audience via Planet Debian. This will contain supplemental information to what I send to the debian-devel-announce mailing list. Want to help? In my platform, I listed some key areas that I'd like to work on. My work won't be limited to those, but it should give you some idea of the type of DPL that I'll be. If you'd like to get involved, feel free to join the #debian-dpl channel on the oftc IRC network, and please introduce yourself along with any areas of interest that you'd like to contribute to.

Wouter Verhelst: Extrepo GitLab update

Earlier this month, GitLab B.V.'s package signing key expired, requiring them to rotate their key. This means that anyone who uses one of their packages needs to jump through a number of manual hoops to update their apt key configuration, which is an annoying manual process that also requires people to download random files from the Internet -- something extrepo was written to prevent. At least they're served over https, but still. I didn't notice until today, but I just updated the extrepo metadata to carry the new key. That means that if you enable one of the GitLab repositories through extrepo enable, you will get the new key rather than the old one. On top of that, if you had already enabled the repository through extrepo, all that is needed for you right now to pull in the new key is to run extrepo update. While I do apologise for the late update, hopefully this should make some people's lives a bit easier. And if GitLab B.V. reads this: please send me a MR to the repository next time, so that we can make process be done in time ;-)

Enrico Zini: Python 2 is dead

It's dead, that's what's wrong with it! It's passed on! This Python is no more! It has ceased to be! It's expired and gone to meet its maker! It's a stiff! Bereft of life, it rests in peace! If you hadn't nailed it to the perch it'd be pushing up the daisies! Its metabolic processes are now 'istory! It's off the twig! It's kicked the bucket, it's shuffled off its mortal coil, run down the curtain and joined the bleedin' choir invisible!! THIS IS AN EX-PYTHON!!

Gunnar Wolf: Fresh, daily built Debian images for your Raspberries (finally!)

So, after I took over or at least, said to take over maintainership of the Raspberry Pi build images originally produced by Michael Stapelberg in mid-2018, I pushed very few updates. Yes, there was some good and visible work, migrated the image-spec repository from GitHub to Salsa, ironed out several outstanding issues, and most important for me managed to get an image built and running for all Raspberry models below the Raspberry Pi 4 Today, I am happy to announce a very good step in the right direction, so I am now

Announcing raspi.debian.net! I have registered and set up an (unofficial!) site, raspi.debian.net, that should serve as a go-grab-it destination for regularly autobuilt images for the Raspberry Pi family. Of course, today you will get an early view of the site. I plan to fix the lack of https due to a mistake on my part WRT the processes at my hosting provider, do some testing in the hardware I have handy (and bless + gpg-sign some images as tested), migrate and update the information in the Debian Wiki, etc. Oh! And I hope to get good news on the Raspberry 4 front, as I know work is actively underway to achieve it.

20 April 2020

Norbert Preining: Gaming: What Remains of Edith Finch

I never thought I could finish a game which is completely linear, has hardly any interaction necessary, hardly any riddles, no fighting. What Remains of Edith Finch taught be differently. And it is amazing.
A friend recently pointed me at a blog about casual games, and surprisingly I found two games I have played on the list: Firewatch and The Witness. One of the other games on the list was What Remains of Edith Finch. This games was lurking in my Steam library for quite some time, and I realized I actually started playing it long ago, but only for a few minutes, before having given up, back then. What a failure I realized! The games plays completely in the now deserted house of the family Finch. The youngest member of the family returns with a key to the house and uncovers the stories of her family. This is about all that is happening in the game. And it is so well done that I couldn t stop playing (wouldn t it be for my daughter interrupting me), and leaves you with the feeling to replay as soon as possible. The graphics are very well done, beautiful scenery, lots of love to details. The story progresses by walking (completely linearly) through the house, and text fragments appearing around you, telling part of the story, small hints, little secrets, everything that makes up a tangible set of family memories.
Exploring the house filled with locked rooms sealed as shrines for the deceased members of the family, Edith uncovers one by one the final moments of her family members, a family seemingly cursed. In these stories the player dives into the world and playing the role of the family members, re-living events of the past.
As I wrote in the beginning don t expect fights, don t expect riddles, but be prepared for an emotional roller coaster, for a deep dive into a well written family history with lots of weird twists. An absolute great game with a playing time of around 2h.

19 April 2020

Enrico Zini: Little wonders

Gibbsdavidl/CatterPlots
devel
Did you ever wish you could make scatter plots with cat shaped points? Now you can! - Gibbsdavidl/CatterPlots
What is the best tool to use for drawing vector pictures? For me and probably for many others, the answer is pretty obvious: Illustrator, or, maybe, Inkscape.
A coloring book to help folks understand how SELinux works. - mairin/selinux-coloring-book
The EURion constellation (also known as Omron rings[1] or doughnuts[2]) is a pattern of symbols incorporated into a number of banknote designs worldwide since about 1996. It is added to help imaging software detect the presence of a banknote in a digital image. Such software can then block the user from reproducing banknotes to prevent counterfeiting using colour photocopiers. According to research from 2004, the EURion constellation is used for colour photocopiers but probably not used in computer software.[3] It has been reported that Adobe Photoshop will not allow editing of an image of a banknote, but in some versions this is believed to be due to a different, unknown digital watermark rather than the EURion constellation.[4][3]
This huge collection of non-scary optical illusions and fascinating visual phenomena emphasizes interactive exploration, beauty, and scientific explanation.
Generated photos are created from scratch by AI systems. All images can be used for any purpose without worrying about copyrights, distribution rights, infringement claims, or royalties.
Dokumentarfilm ber die Rangierer im Bahnhof Dresden-Friedrichstadt in der DDR aus dem Jahr 1984.
Il termine sardo femina accabadora, femina agabbad ra o, pi comunemente, agabbadora o accabadora (s'agabbad ra, lett. "colei che finisce", deriva dal sardo s'acabbu, "la fine" o dallo spagnolo acabar, "terminare") denota la figura storicamente incerta di una donna che si incaricava di portare la morte a persone di qualunque et , nel caso in cui queste fossero in condizioni di malattia tali da portare i familiari o la stessa vittima a richiederla. In realt non ci sono prove di tale pratica, che avrebbe riguardato alcune regioni sarde come Marghine, Planargia e Gallura[1]. La pratica non doveva essere retribuita dai parenti del malato poich il pagare per dare la morte era contrario ai dettami religiosi e della superstizione.
Alright the people have spoken and they want more cat genetics. So, I present to you all "Cat Coat Genetics 101: A Tweetorial", feat. pics of many real life cats (for science, of course...this baby is Caterpillar).

Dirk Eddelbuettel: prrd 0.0.3: More improvements

Back in early 2018, the prrd package was introduced as release 0.0.1, uploaded to CRAN, and updated once as release 0.0.2. I have used it extensively for every CRAN release of Rcpp, RcppArmadillo, RcppEigen, BH, and possibly others. The idea of prrd is simple, and described in some more detail on its webpage and its GitHub repo. Reverse dependency checks are an important part of package development and is easily done in a (serial) loop. But these checks are also generally embarassingly parallel as there is no or little interdependency between them (besides maybe shared build depedencies). See the following (dated) screenshot (running six parallel workers, arranged in split byobu session). Since the two early releases, I made a few changes to e.g. the analysis of package checks and their summaries (but never pushed these) as well as a few usability enhancements. This release regroups these. The release is summarised in the NEWS entry:

Changes in prrd version 0.0.3 (2020-04-19)
  • Extended functionality summarise() with optional use of package foghorn (Dirk)
  • New scripts enqueueDepends, dequeueDepends and summmariseJobs (Dirk)
  • Added tweaks and enhancements throughout (Dirk)
  • The default queue location can now be set via options (Dirk)
  • Meta-data on package, version and date is now stored, and shown on dequeue startup (Dirk)
  • The README.md was clarified and improved (Dirk, Avraham Adler in #8, Robert Nuske in #10)

CRANberries provides the usual summary of changes to the previous version. See the aforementioned webpage and its repo for details. For more questions or comments use the issue tracker off the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Bits from Debian: DPL elections 2020, congratulations Jonathan Carter!

The Debian Project Leader elections just finished and the winner is Jonathan Carter! His term as project leader starts next Tuesday April 21st and expires on April 20th 2021. Of a total of 1011 developers, 339 developers voted using the Condorcet method. More information about the result is available in the Debian Project Leader Elections 2020 page. Many thanks to Jonathan Carter, Sruthi Chandran and Brian Gupta for running. And special thanks to Sam Hartman for his service as DPL during these last twelve months!

Sven Hoexter: Emulating Raspi2 like hardware with Rasbian in 2020

To follow some older (as in two years) ARM assembler howto, I searched for a quick and dirty way to run a current Rasbian with qemu 4.2 on Debian/unstable. The end result are the following notes to get that up and running:
# Download a binary device tree file and matching kernel a good soul uploaded to github
wget https://github.com/vfdev-5/qemu-rpi2-vexpress/raw/master/kernel-qemu-4.4.1-vexpress
wget https://github.com/vfdev-5/qemu-rpi2-vexpress/raw/master/vexpress-v2p-ca15-tc1.dtb
# Download the official Rasbian image without X
wget -O raspbian_lite_latest.zip https://downloads.raspberrypi.org/raspbian_lite_latest
unzip raspbian_lite_latest.zip
# Convert it from the raw image to a qcow2 image and add some space
qemu-img convert -f raw -O qcow2 2020-02-13-raspbian-buster-lite.img rasbian.qcow2
qemu-img resize rasbian.qcow2 +2G
# start qemu
qemu-system-arm -m 2048M -M vexpress-a15 -cpu cortex-a15 \
 -kernel kernel-qemu-4.4.1-vexpress -no-reboot \
 -smp 2 -serial stdio \
 -dtb vexpress-v2p-ca15-tc1.dtb -sd rasbian.qcow2 \
 -append "root=/dev/mmcblk0p2 rw rootfstype=ext4 console=ttyAMA0,15200 loglevel=8" \
 -nic user,hostfwd=tcp::5555-:22
# login at the serial console as user pi with password raspberry
sudo -i
# enable ssh
systemctl enable ssh
# resize partition and filesystem
parted /dev/mmcblk0 resizepart 2 100%
resize2fs /dev/mmcblk0p2
Now I can login via ssh and start to play:
ssh pi@localhost -p 5555
So for me that is sufficient, I have network connectivity to install an editor, transfer files and can otherwise work with tmux to have some session multiplexing. Additional Notes

Russ Allbery: Review: Beyond the Galaxy

Review: Beyond the Galaxy, by Ethan Siegel
Publisher: World Scientific
Copyright: 2016
ISBN: 981-4667-16-1
Format: Kindle
Pages: 370
In the preface of this book, Ethan Siegel recounts his experience as a new college professor in 2009, thrilled to learn that he would be teaching the college's introductory astronomy class. The only disappointment was that he could not find a textbook that described astronomy the way that he wanted to teach it. Siegel did not want to simply describe the current astronomical understanding. He wanted to start at the beginning and tell a story. What questions did we start with? How did we answer them? What new questions did those answers provoke? I enjoyed Sabine Hossenfelder's Lost in Math, but I'm even happier that she included in it a recommendation of Beyond the Galaxy as a good introduction to modern astronomy. I am completely in agreement with Siegel: Astronomy is interesting however it is described, but the best presentation for the interested lay person who does not intend to become a professional astronomy is chronological. (I feel the same way about physics and mathematics.) The narrative structure of scientific discovery draws me in every time. It's so satisfying to see our knowledge growing, breakthrough by breakthrough, only to meet the next puzzling inconsistency. It also is a natural fit for bringing someone up to speed on a field, since the history of the field starts with simpler questions and problems, and the complications of later discoveries build on the gaps left by earlier theories. Siegel tells that story well. Beyond the Galaxy starts with observations of seasonal changes in the path of the Sun through the sky and phases of the moon, quickly moves on to Eratosthenes's calculation of the circumference of the Earth, and continues at pace through early astronomy. The first chapter brings the reader up to the start of the 20th century, after which Siegel slows down and spends the remaining 10 chapters on the last 100 years: special and general relativity, the expansion of the universe, the Big Bang, dark matter, dark energy, the inflationary period, and more. For me, this was perfect. The story of early astronomy and the fight over the heliocentric model of the universe is worth telling, but it's been told many times before and features prominently in history books outside of science classes. The weight of material in this book matched my interest: What new developments have there been after general relativity and the Big Bang theory? What inconsistencies are dark matter and dark energy explaining? What is the inflationary period and how did it modify the Big Bang theory? (My half-formed impression of this part of astronomy from news articles turned out to be almost entirely wrong.) And how do we know all of this? The question of how we know as much as we do about the early origins of the universe turned out to be far more interesting than I had realized. It's one of those pieces of science where, when given only the conclusions, it's hard to imagine how our theories could be as complete as they are. Siegel is a bit repetitive in how he talks about theory development and occasionally skims over the details to avoid getting too deep into techniques and math, but he does a great job explaining the predictions of a theory, the design of experiments to prove or disprove those predictions, and the implications for the boundaries of what we know. This is the first time someone has explained the theorized origin of matter-antimatter asymmetry in sufficient detail that I was able to understand and internalize it. Dark matter and dark energy are the current topics of astronomy that get the most press, and the coverage of both is very good here. I was particularly fascinated by the link between dark matter and the superstructures of the universe that we've discovered. Astronomy does scale in a way that no other science can manage, and the scale of structure we've discovered and been able to map has gone up considerably since the last time I refreshed my astronomical knowledge. If you're looking for a math-light, comprehensive introduction to modern astronomy, I can wholeheartedly recommend this book. That goes double if you, like me, prefer a chronological view of scientific discovery so that you can understand what questions people were trying to answer and how our understanding changed over time. One note on format: Astronomy being what it is, this book is very heavy on pictures. It is not at all suitable for a dedicated ebook reader. The Kindle tries, but the combination of a small screen and black and white e-ink fail miserably. I switched to reading on a tablet, and that was a far better experience. The Kindle app still struggles to put the figures next to the text that discusses them, but that's a typesetting problem that I often have with physical books as well. If you don't have a tablet and you aren't willing to read on a computer screen, you probably want a physical copy of this one (which, sadly, means academic textbook pricing). Rating: 8 out of 10

18 April 2020

Jonathan Dowland: How many function arguments?

In Haskell (and many other functional languages) it's quite common for the implementation of a function to reference one less argument than the type signature declares:
g :: foo -> bar
g = length . reverse
Known as point-free style by proponents (and pointless style by opponents), the function definition is a list of other functions which are composed together to produce a composite requiring a single argument: the missing one. Sometimes I come across the opposite: a function with a type signature and a definition beginning in a way similar to this
f :: foo -> bar
f a b =  
That is, the type signature declares that the function accepts a single argument of type foo, but the definition is in terms of two arguments. Huh? What's going on is that bar is really a type synonym for another function. In other words
type bar = baz -> qux
So we can consider f to actually be
f :: foo -> baz -> qux
With this definition of bar, in the definition of f above, the second parameter b maps to the type baz. When I've encountered this, I strongly suspect what has happened is the function was originally written with the longer type signature, and later on the type synonym was declared and function signatures updated to use it. I'm not aware of anyone advocating for this style.

Jonathan McDowell: Building a very minimal initramfs

I m working on trying to get a Qualcomm IPQ8064 device working properly. I d got as far as an extremely hacked up chain of networking booting and the serial console working, so the next stage was to try and get a basic userland in place to try and make poking things a bit easier. While I have a cross-compiling environment all setup (that s how I m building my kernels) I didn t really want to get into something complicated just to be able to poke around sysfs etc. I figured I could use a static BusyBox in an initramfs. I was right, but there were a couple of hiccups along the way so I m writing it up so I remember next time. First, I cheated and downloaded a prebuilt static binary from https://busybox.net/downloads/binaries/ (very convenient, thanks) - the IPQ8064 is a dual core ARMv7 so I used busybox-armv7l. There were various sites with init scripts to go along with this; I ended up with a variation of Star Brilliant s gist:
Minimal init script
#!/bin/busybox sh
busybox mkdir -p /dev /etc /proc /root /sbin /sys /usr/bin /usr/sbin
busybox mount -t proc proc /proc
busybox mount -t sysfs sys /sys
busybox mount -t devtmpfs dev /dev
echo Starting up...
echo ttyMSM0::respawn:/sbin/getty -L ttyMSM0 115200 vt100 >> /etc/inittab
echo Login with root and no password. > /etc/issue
echo >> /etc/issue
echo root::0:0:root:/root:/bin/sh > /etc/passwd
busybox mdev -s
busybox --install
hostname localhost
ip link set lo up
echo 5 > /proc/sys/kernel/printk
exec /linuxrc
busybox and the init script aren t sufficient. If you have any problems then you re going to want a console device. Otherwise you ll do what I did, forget to change one of the tty references in the script to the right device, and spend too long trying to figure out why you re not getting any output as soon as you start running userspace. It turns out that CONFIG_DEVTMPFS_MOUNT isn t sufficient for the initramfs (the Kconfig help even tells you that). So I need to create a /dev/console device file inside the initramfs too. And I don t build as root (and you shouldn t either) which makes creating a device node hard. It s ok though, because the Linux kernel doesn t need you to be root to build it, and it has a default initramfs with a console device in it. This is helpfully generated using usr/gen_init_cpio, which takes a file defining what you want to put in the cpio file that becomes your initramfs. I used the following:
Minimal initramfs creation file
# Simple busybox based initramfs
dir /dev 0755 0 0
nod /dev/console 0600 0 0 c 5 1
dir /root 0700 0 0
dir /bin 0755 0 0
dir /sbin 0755 0 0
file /init basic-init 0755 0 0
file /bin/busybox busybox-armv7l 0755 0 0
All that then needs to be done is linux/usr/gen_init_cpio initramfs.list > initramfs.cpio and the resulting initramfs.cpio is suitable for inclusion in your kernel. The precompiled binaries have a lot of stuff enabled, which makes for a pretty useful debugging environment with fairly minimal work.

17 April 2020

Julien Danjou: Being in Charge

Being in ChargeIf you never heard of the 10x engineer myth, it's a pretty great concept. It boils down to the idea where an engineer could be 10x more efficient than a random engineer. I find this fantastically twisted.Last week, I sat and chat with Alexis Monville in Le Podcast a podcast that equips you to make positive change in your organization. We talked about that 10x Engineer myth, and from there we digressed on how to grow your career and handle the different aspects of it.This was a very interesting exchange. Alexis is actually going to publish a new book next month (May 2020) entitled I am a Software Engineer and I am in charge.
Being in Charge
Lucky me, this week, I had the chance to be able to read the book before everybody else which means I actually read after our recording. I understood why Alexis said that a lot of what I was talking about during our podcast resonated with him. I send a detailed review of the book to Alexis and Michael if you're curious. I'm definitely recommending this book if you want to stop complaining about your job and start understanding how to pull the strings.I wish I had this book available 10 years ago!

Daniel Kahn Gillmor: Tech-assisted Contact-Tracing against the COVID-19 pandemic

Today at the ACLU, we released a whitepaper discussing how to evaluate some novel cryptographic schemes that are being considered to provide technology-assisted contact-tracing in the face of the COVID-19 pandemic. The document offers guidelines for thinking about potential schemes like this, and what kinds of safeguards we need to expect and demand from these systems so that we might try to address the (hopefully temporary) crisis of the pandemic without also creating a permanent crisis for civil liberties. The proposals that we're seeing (including PACT, DP^3T, TCN, and the Apple/Google proposal) work in pretty similar ways, and the challenges and tradeoffs there are remarkably similar to Internet protocol design decisions. Only now in addition to bytes and packets and questions of efficiency, privacy, and control, we're also dealing directly with risk of physical harm (who gets sick?), society-wide allocation of scarce and critical resources (who gets tested? who gets treatment?), and potentially serious means of exercising powerful social control (who gets forced into quarantine?). My ACLU colleague Jon Callas and i will be doing a Reddit AMA in r/Coronavirus tomorrow starting at 2020-04-17T19:00:00Z (that's 3pm Friday in TZ=America/New_York) about this very topic, if that's the kind of thing you're into.

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