Search Results: "Jonathan McDowell"

24 January 2017

Jonathan McDowell: Experiments with 1-Wire

As previously mentioned, at the end of last year I got involved with a project involving the use of 1-Wire. In particular a DS28E15 device, intended to be used as a royalty tracker for a licensed piece of hardware IP. I d no previous experience with 1-Wire (other than knowing it s commonly used for driving temperature sensors), so I took it as an opportunity to learn a bit more about it. The primary goal was to program a suitable shared key into the DS28E15 device that would also be present in the corresponding hardware device. A Maxim programmer had been ordered, but wasn t available in stock so had to be back ordered. Of course I turned to my trusty Bus Pirate, which claimed 1-Wire support. However it failed to recognise the presence of the device at all. After much head scratching I finally listened to a co-worker who had suggested it was a clock speed issue - the absence of any option to select the 1-Wire speed in the Bus Pirate or any mention of different speeds in the documentation I had read had made me doubt it was an issue. Turns out that the Bus Pirate was talking standard 1-Wire and the DS28E15 only talks overdrive 1-Wire, to the extent that it won t even announce its presence if the reset pulse conforms to the standard, rather than overdrive, reset time period. Lesson learned: listen to your co-workers sooner. A brief period of yak shaving led to adding support to the Bus Pirate for the overdrive mode (since landed in upstream), and resulted in a search request via the BP interface correctly finding the device and displaying its ROM ID. This allowed exploration of the various commands the authenticator supports, to verify that the programming sequence operated as expected. These allow for setting the shared secret, performing a SHA256 MAC against this secret and a suitable nonce, and retrieving the result. Next problem: the retrieved SHA256 MAC did not match the locally computed value. Initially endianness issues were suspected, but trying the relevant permutations did not help. Some searching found an implementation of SHA256 for the DS28E15 that showed differences between a standard SHA256 computation and what the authenticator performs. In particular SHA256 normally adds the current working state (a-g) to the current hash value (h0-h7) at the end of every block. The authenticator does this for all but the final block, where instead the hash value is set to the working state. I haven t been able to find any documentation from Maxim that this is how things are calculated, nor have I seen any generic implementation of SHA256 which supports this mode. However rolling my own C implementation based on the code I found and using it to compare the results retrieved from the device confirms that this is what s happening. So at this point we re done, right? Wait for the proper programming hardware to turn up, write the key to the devices, profit? Well, no. There was a bit of a saga involving the programmer (actually programmers, one with at least some documentation that allowed the creation of a Python tool to allow setting the key and reading + recording the ROM ID for tracking, and one with no programming documentation that came with a fancy GUI for manually doing the programming), but more importantly it was necessary to confirm that the programmed device interacted with the hardware correctly. Initial testing with the hardware was unsuccessful. Again endianness issues were considered and permutations tried, but without success. A simple key constructed to avoid such issues was tried, and things worked fine. There was a hardware simulation of both components available, so it was decided to run that and obtain a capture of the traffic between them. As the secret key was known this would then allow the random nonce to be captured, and the corresponding (correct) hash value. Tests could then be performed in software to determine what the issue was & how to generate the same hash for verification. Two sets of analyzer software were tried, OpenBench LogicSniffer (OLS) and sigrok. As it happened both failed to correctly decode the bitstream detected as 1-Wire, but were able to show the captured data graphically, allowing for decoding by eye. A slight patch to OLS to relax the timing constraints allowed it to successfully decode the full capture and provided the appropriate data for software reproduction. The end issue? A 256 bit number (as defined in VHDL) is not the same as 32 element byte array Obvious when you know what the issue is! So? What did I learn, other than a lot about 1-Wire? Firstly, don t offhandedly discount suggestions that you don t think make sense. Secondly, having a tool (in this case the Bus Pirate) that lets you easily play with a protocol via a simple interface is invaluable in understanding it. Thirdly, don t trust manufacturers to be doing something in a normal fashion when they claim to be using a well defined technology. Fourthly, be conscious about all of the different ways bitstreams can be actually processed in memory. It s not just endianness. Finally, spending the time to actually understand what s going on up front can really help when things don t work as you d expect later on - without the yak shaving to support Overdrive on the BP I wouldn t have been able to so quickly use the simulation capture to help diagnose the issue.

14 January 2017

Jonathan McDowell: Cloning a USB LED device

A month or so ago I got involved in a discussion on IRC about notification methods for a headless NAS. One of the options considered was some sort of USB attached LED. DealExtreme had a cheap Webmail notifier , which was already supported by mainline kernels as a Riso Kagaku device but it had been sold out for some time. This seemed like a fun problem to solve with a tinyAVR and V-USB. I had my USB relay board so I figured I could use that to at least get some code to the point that the kernel detected it as the right device, and the relay output could be configured as one of the colours to ensure it was being driven in roughly the right manner. The lack of a full lsusb dump (at least when I started out) made things a bit harder, plus the fact that the Riso uses an output report unlike the relay code, which uses a control message. However I had the kernel source for the driver and with a little bit of experimentation had something which would cause the driver to be loaded and the appropriate files in /sys/class/leds/ to be created. The relay was then successfully activated when the red LED was supposed to be on. 
hid-led 0003:1294:1320.0001: hidraw0: USB HID v1.01 Device [MAIL  MAIL ] on usb-0000:00:14.0-6.2/input0
hid-led 0003:1294:1320.0001: Riso Kagaku Webmail Notifier initialized
I subsequently ordered some Digispark clones and modified the code to reflect the pins there (my relay board used pins 1+2 for USB, the Digispark uses pins 3+4). I then soldered a tricolour LED to the board, plugged it in and had a clone of the Riso Kaguku device for about 1.50 in parts (no doubt much cheaper in bulk). Very chuffed. In case it s useful to someone, the code is released under GPLv3+ and is available at https://the.earth.li/gitweb/?p=riso-kagaku-clone.git;a=summary or on GitHub at https://github.com/u1f35c/riso-kagaku-clone. I m seeing occasional issues on an older Dell machine that only does USB2 with enumeration, but it generally is fine once it gets over that. (FWIW, Jon, who started the original discussion, ended up with a BlinkStick Nano which is a neater device with 2 LEDs but still based on an Tiny85.)

6 January 2017

Jonathan McDowell: 2016 in 50 Words

Idea via Roger. Roughly chronological order. Some things were obvious inclusions but it was interesting to go back and look at the year to get to the full 50 words. Speaking at BelFOSS. Earthlings birthday. ATtiny hacking. Speaking at ISCTSJ. Dublin Anomaly. Co-habiting. DebConf. Peak Lion. Laura s wedding. Christmas + picnic. Engagement. Car accident. Car write off. Tennent s Vital. Dissertation. OMGWTFBBQ. BSides. New job. Rachel s wedding. Digital Privacy talk. Graduation. All The Christmas Dinners. IMDB Top 250. Shay leaving drinks. (This also serves as a test to see if I ve correctly updated Planet Debian to use https and my new Hackergotchi that at least looks a bit more like I currently do.)

31 December 2016

Jonathan McDowell: IMDB Top 250: Complete. Sort of.

Back in 2010, inspired by Juliet, I set about doing 101 things in 1001 days. I had various levels of success, but one of the things I did complete was the aim of watching half of the IMDB Top 250. I didn t stop at that point, but continued to work through it at a much slower pace until I realised that through the Queen s library I had access to quite a few DVDs of things I was missing, and that it was perfectly possible to complete the list by the end of 2016. So I did. I should point out that I didn t set out to watch the list because I m some massive film buff. It was more a mixture of watching things that I wouldn t otherwise choose to, and also watching things I knew were providing cultural underpinnings to films I had already watched and enjoyed. That said, people have asked for some sort of write up when I was done. So here are some random observations, which are almost certainly not what they were looking for.

My favourite film is not in the Top 250 First question anyone asks is What s your favourite film? . That depends a lot on what I m in the mood for really, but fairly consistently my answer is The Hunt for Red October. This has never been in the Top 250 that I ve noticed. Which either says a lot about my taste in films, or the Top 250, or both. Das Boot was in the list and I would highly recommend it (but then I like all submarine movies it seems).

The Shawshank Redemption is overrated I can t recall a time when The Shawshank Redemption was not top of the list. It s a good film, and I ve watched it many times, but I don t think it s good enough to justify its seemingly unbroken run. I don t have a suggestion for a replacement, however.

The list is constantly changing I say I ve completed the Top 250, but that s working from a snapshot I took back in 2010. Today the site is telling me I ve watched 215 of the current list. Last night it was 214 and I haven t watched anything in between. Some of those are films released since 2010 (in particular new releases often enter high and then fall out of the list over a month or two), but the current list has films as old as 1928 (The Passion of Joan of Arc) that weren t there back in 2010. So keeping up to date is not simply a matter of watching new releases.

The best way to watch the list is terrestrial TV There were various methods I used to watch the list. Some I d seen in the cinema when they came out (or was able to catch that way anyway - the QFT showed Duck Soup, for example). Netflix and Amazon Video had some films, but overall a very disappointing percentage. The QUB Library, as previously mentioned, had a good number of DVDs on the list (especially the older things). I ended up buying a few (Dial M for Murder on 3D Bluray was well worth it; it s beautifully shot and unobtrusively 3D), borrowed a few from friends and ended up finishing off the list by a Lovefilm one month free trial. The single best source, however, was UK terrestrial TV. Over the past 6 years Freeview (the free-to-air service here) had the highest percentage of the list available. Of course this requires some degree of organisation to make sure you don t miss things.

Films I enjoyed Not necessarily my favourite, but things I wouldn t have necessarily watched and was pleasantly surprised by. No particular order, and I m leaving out a lot of films I really enjoyed but would have got around to watching anyway.
  • Clint Eastwood films - Gran Torino and Million Dollar Baby were both excellent but neither would have appealed to me at first glance. I hated Unforgiven though.
  • Jimmy Stewart. I m not a fan of It s a Wonderful Life (which I d already watched because it s Lister s favourite film), but Harvey is obviously the basis of lots of imaginary friend movies and Rear Window explained a Simpsons episode (there were a lot of Simpsons episodes explained by watching the list).
  • Spaghetti Westerns. I wouldn t have thought they were my thing, but I really enjoyed the Sergio Leone films (A Fistful of Dollars etc.). You can see where Tarantino gets a lot of his inspiration.
  • Foreign language films. I wouldn t normally seek these out. And in general it seems I cannot get on with Italian films (except Life is Beautiful), but Amores Perros, Amelie and Ikiru were all better than expected.
  • Kind Hearts and Coronets. For some reason I didn t watch this until almost the end; I think the title always put me off. Turned out to be very enjoyable.

Films I didn t enjoy I m sure these mark me out as not being a film buff, but there are various things I would have turned off if I d caught them by accident rather than setting out to watch them. I ve kept the full list available, if you re curious.

25 December 2016

Jonathan McDowell: The terrible PIC ecosystem

I recently had call to play with some 1-Wire devices at work (more of which in a future post). It was taking a while for the appropriate programmer to turn up, so of course I pulled out my trusty BusPirate. It turned out the devices in question would only talk in overdrive mode, while the Bus Pirate could only offer standard mode. So I set about trying to figure out how to add the appropriate support. This is is a huge endorsement for test equipment with Free Software firmware. Rather than giving up I was able to go and grab the current firmware, which has been adopted by the community since Dangerous Prototypes have discontinued development. What let me down was the ecosystem around the PIC24FJ64GA002. My previous recent experience with microcontrollers has been with the ATTiny range and the STM32. Getting up and running with both of these was fairly easy - the tool chains necessary were already present in Debian, so all it took was a simple apt invocation to install everything I needed to compile code and program it to the devices. Not so with the PIC series, which surprised me. There seems to be some basic support for the earlier PIC16 range, but for later chips there s nothing that works out of the box with Debian. Investigation revealed that this was because there s nothing maintained that enabled Free development for the PIC range. The accepted solution is the closed MPLAB X. Now, in one sense fair play to Microchip for making this available. But in another, shame on you. I can t imagine ever choosing to build something based on a chip that only had a closed source tool chain available. I want things I can use in Makefiles and properly script, that are available in my distro of choice and that generally work in the same fashion as the tool chains I m used to. I understand there might be some benefit in a closed compiler in terms of performance (and have HPC friends who would never trust a benchmark provided using GCC), but in general that s not the space I move in. Nor does it seem to be the sort of attitude you should be taking if you are trying to attract the hobbyist and small production run market. Any yet this seems common amongst hardware manufacturers. People whose core business is selling physical items, where the software is only relevant in terms of being able to use those items, seem to consider the software to be precious. Instead of opening up programming specifications and allowing a more widespread use of the hardware, increasing sales. I understand there are some cases where this isn t practical, but the default attitude is definitely one of being closed rather than open, which is a terrible shame. Anyway. I do have some Bus Pirate 1-Wire overdrive support now working (pending some testing to ensure standard mode still works), but I am glad I never spent a lot of time getting involved with PICs now.

18 December 2016

Jonathan McDowell: Timezones + static blog generation

So, it turns out when you move to static blog generation and do the generation on your laptop, which is usually in the timezone you re currently physically located, it can cause URLs to change. Especially if you re prone to blogging late at night, which can result in even just a shift to DST changing things. I ve forced jekyll to UTC by adding timezone: 'UTC' to the config, and ensuring all the posts now have timezones for when they were written (a lot of the imported ones didn t), so hopefully things should be stable from here on.

12 December 2016

Jonathan McDowell: No longer a student. Again.

99 Problems (image courtesy of XKCD) Last week I graduated with a Masters in Legal Science (now taught as an MLaw) from Queen s University Belfast. I m pleased to have achieved a Distinction, as well an award for Outstanding Achievement in the Dissertation (which was on the infringement of privacy by private organisations due to state mandated surveillance and retention laws - pretty topical given the unfortunate introduction of the Investigatory Powers Act 2016). However, as previously stated, I had made the decision that I was happier building things, and wanted to return to the world of technology. I talked to a bunch of interesting options, got to various stages in the hiring process with each of them, and happily accepted a role with Titan IC Systems which started at the beginning of September. Titan have produced a hardware accelerated regular expression processor (hence the XKCD reference); the RXP in its FPGA variant (what I get to play with) can handle pattern matching against 40Gb/s of traffic. Which is kinda interesting, as it lends itself to a whole range of applications from network scanning to data mining to, well, anything where you want to sift through a large amount of data checking against a large number of rules. However it s brand new technology for me to get up to speed with (plus getting back into a regular working pattern rather than academentia), and the combination of that and spending most of the summer post DebConf wrapping up the dissertation has meant I haven t had as much time to devote other things as I d have liked. However I ve a few side projects at various stages of completion and will try to manage more regular updates.

1 October 2016

Vincent Sanders: Paul Hollywood and the pistoris stone

There has been a great deal of comment among my friends recently about a particularly British cookery program called "The Great British Bake Off". There has been some controversy as the program is moving from the BBC to a commercial broadcaster.

Part of this discussion comes from all the presenters, excepting Paul Hollywood, declining to sign with the new broadcaster and partly because of speculation the BBC might continue with a similar format show with a new name.

Rob Kendrick provided the start to this conversation by passing on a satirical link suggesting Samuel L Jackson might host "cakes on a plane"

This caused a large number of suggestions for alternate names which I will be reporting but Rob Kendrick, Vivek Das Mohapatra, Colin Watson, Jonathan McDowell, Oki Kuma, Dan Alderman, Dagfinn Ilmari Manns ke, Lesley Mitchell and Daniel Silverstone are the ones to blame.




So that is our list, anyone else got better ideas?

3 July 2016

Jonathan McDowell: Confirming all use of an SSH agent

For a long time I ve wanted an ssh-agent setup that would ask me before every use, so I could slightly more comfortably forward authentication over SSH without worrying that my session might get hijacked somewhere at the remote end (I often find myself wanting to pull authenticated git repos on remote hosts). I m at DebConf this week, which is an ideal time to dig further into these things, so I did so today. As is often the case it turns out this is already possible, if you know how. I began with a setup that was using GNOME Keyring to manage my SSH keys. This isn t quite what I want (eventually I want to get to the point that I can sometimes forward a GPG agent to remote hosts for signing purposes as well), so I set about setting up gpg-agent. I used Chris excellent guide to GnuPG/SSH Agent setup as a starting point and ended up doing the following: 
$ echo use-agent >> ~/.gnupg/options
$ echo enable-ssh-support >> ~/.gnupg/gpg-agent.conf
$ sudo sed -i.bak "s/^use-ssh-agent/# use-ssh-agent/" /etc/X11/Xsession.options
$ sudo rm /etc/xdg/autostart/gnome-keyring-ssh.desktop
The first 2 commands setup my local agent, and told it to do SSH agent foo. The next stopped X from firing up ssh-agent, and the final one prevents GNOME Keyring from being configured to be the SSH agent, without having to remove libpam-gnome-keyring as Chris did. After the above I logged out of and into X again, and could see ~/.gnupg/S.gpg-agent.ssh getting created and env grep SSH showing SSH_AUTH_SOCK pointing to it (if GNOME Keyring is still handling things it ends up pointing to something like /run/user/1000/keyring/ssh). [Update: Luca Capello emailed to point out this was a bad approach; there s thankfully no need to do the last 2 commands that require root. #767341 removed the need to edit Xsession.options and you can prevent GNOME Keyring starting on a per user basis with: 
(cat /etc/xdg/autostart/gnome-keyring-ssh.desktop ;
 echo 'X-GNOME-Autostart-enabled=false') > \
 ~/.config/autostart/gnome-keyring-ssh.desktop
] After this it turned out all I need to do was ssh-add -c <ssh keyfile>. The -c says confirm use and results in the confirm flag being appended to the end of ~/.gnupg/sshcontrol (so if you ve already done the ssh-add you can go and add the confirm if that s the behaviour you d like). Simple when you know how, but I ve had conversations with several people in the past who wanted the same thing and hadn t figured out how, so hopefully this is helpful to others.

1 July 2016

Rapha&#235;l Hertzog: My Free Software Activities in June 2016

My monthly report covers a large part of what I have been doing in the free software world. I write it for my donators (thanks to them!) but also for the wider Debian community because it can give ideas to newcomers and it s one of the best ways to find volunteers to work with me on projects that matter to me. Debian packaging Django and Python. I uploaded Django 1.9.7 and filed an upstream ticket (#26755) for a failure seen in its DEP-8 tests. I packaged/sponsored python-django-modeltranslation and python-paypal. I opened a pull request on model-translation to fix failing tests in the Debian package build. I packaged a new python-django-jsonfield (1.0.0), filed a bug and discovered some regression in its PostgreSQL support. I helped on the upstream ticket and I have been granted commit rights. I used this opportunity to do some bug triage and push a few fixes. I also discussed the future of the module and ended up starting a discussion on Django s developer list about the possibility to add a JSONField to the core. CppUTest. I uploaded a new upstream version (3.8) with more than a year of work. I found out that make install does not install a required header so I opened a ticket with a patch. The package ended up not compiling on quite a few architectures so I opened a ticket and prepared a fix for some of those failures with the help of the upstream developers. I also added a DEP-8 tests after having uploaded a broken (untested) package systemd support in net-snmp and postfix. I worked on adding native systemd service units to net-snmp (#782243) and postfix (#715188). In both cases, the maintainers have not been very reactive so far so I uploaded my changes as delayed NMU. pkg-security team. The team that I started quietly a few months ago is now growing, both with new members and new packages. I created the required Teams/pkg-security wiki page. I sponsored xprobe, hydra, made an upload of medusa to merge Kali changes into Debian (and at the same time submitting the patch to upstream). fontconfig. After having read Jonathan McDowell s analysis of a bug that I experienced multiple times (and that many Kali users had too), I opened bug #828037 to get it fixed once for all. Unfortunately, nothing happened yet. DebConf 16 I spent some time to prepare the 2 talks and the BoF that I will give/manage in Cape Town next week: Distro Tracker I continued to mentor Vladimir Likic who managed to finish his first patch. He is now working on documentation for new contributors based on his recent experience. I enhanced the tox configuration to run tests with Django 1.8 LTS with fatal warnings (python -Werror) so as to ensure that I m not relying on any deprecated feature and so that I can be sure that the codebase will work on the next Django LTS release (1.11). Thanks to this, I did discover quite a few places where I have been using deprecated API and I fixed them all (the JSONField update to 1.0.0 I mentionned above was precisely to fix such a warning). I also fixed a few more issues with folded mail headers that you can t inject back in a new Message object and with messages lacking the subject field. All those have been caught through real (spam) email generating exceptions wich are then mailed to me. Kali related work I uploaded a new live-boot (5.20160608) to Debian to fix a bug where the boot process was blocking on some timeout. I forwarded a Kali bug against libatk-wrapper-java (#827741) which turned out to be an OpenJDK bug. I filed #827749 against reprepro to request a way to remove selected internal file references. This is required if you want to be able to make a file disappear and if that file is part of a snapshot that you want to keep despite this. But in truth, my real need is to be able to replace the .orig.tar.gz used by Kali by the orig.tar.gz used by Debian those conflicts break the mirroring/import script. Salt I have been using salt to deploy a new service, and I developed patches for a few issues in salt formulas. I also created a new letsencrypt-sh formula to manage TLS certificates with the letsencrypt.sh ACME client. Thanks See you next month for a new summary of my activities.

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27 June 2016

Jonathan McDowell: Hire me!

It s rare to be in a position to be able to publicly announce you re looking for a new job, but as the opportunity is currently available to me I feel I should take advantage of it. That s especially true given the fact I ll be at DebConf 16 next week and hope to be able to talk to various people who might be hiring (and will, of course, be attending the job fair). I m coming to the end of my Masters in Legal Science and although it s been fascinating I ve made the decision that I want to return to the world of tech. I like building things too much it seems. There are various people I ve already reached out to, and more that are on my list to contact, but I figure making it more widely known that I m in the market can t hurt with finding the right fit. I m on LinkedIn and OpenHUB, which should give a bit more info on my previous experience and skill set. I know I m light on details here, so feel free to email me to talk about what I might be able to specifically bring to your organisation.

23 June 2016

Jonathan McDowell: Fixing missing text in Firefox

Every now and again I get this problem where Firefox won t render text correctly (on a Debian/stretch system). Most websites are fine, but the odd site just shows up with blanks where the text should be. Initially I thought it was NoScript, but turning that off didn t help. Daniel Silverstone gave me a pointer today that the pages in question were using webfonts, and that provided enough information to dig deeper. The sites in question were using Cantarell, via: 
src: local('Cantarell Regular'), local('Cantarell-Regular'), url(cantarell.woff2) format('woff2'), url(cantarell.woff) format('woff');
The Firefox web dev inspector didn t show it trying to fetch the font remotely, so I removed the local() elements from the CSS. That fixed the page, letting me pinpoint the problem as a local font issue. I have fonts-cantarell installed so at first I tried to remove it, but that breaks gnome-core. So instead I did an fc-list grep -i cant to ask fontconfig what it thought was happening. That gave: 
/usr/share/fonts/opentype/cantarell/Cantarell-Regular.otf.dpkg-tmp: Cantarell:style=Regular
/usr/share/fonts/opentype/cantarell/Cantarell-Bold.otf.dpkg-tmp: Cantarell:style=Bold
/usr/share/fonts/opentype/cantarell/Cantarell-Bold.otf: Cantarell:style=Bold
/usr/share/fonts/opentype/cantarell/Cantarell-Oblique.otf: Cantarell:style=Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-Regular.otf: Cantarell:style=Regular
/usr/share/fonts/opentype/cantarell/Cantarell-Bold-Oblique.otf: Cantarell:style=Bold-Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-Oblique.otf.dpkg-tmp: Cantarell:style=Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-BoldOblique.otf: Cantarell:style=BoldOblique
Hmmm. Those .dpkg-tmp files looked odd, and sure enough they didn t actually exist. So I did a sudo fc-cache -f -v to force a rebuild of the font cache and restarted Firefox (it didn t seem to work before doing so) and everything works fine now. It seems that fc-cache must have been run at some point when dpkg had not yet completed installing an update to the fonts-cantarell package. That seems like a bug - fontconfig should probably ignore .dpkg* files, but equally I wouldn t expect it to be run before dpkg had finished its unpacking stage fully.

18 May 2016

Jonathan McDowell: First steps with the ATtiny45

1 port USB Relay
These days the phrase embedded usually means no console (except, if you re lucky, console on a UART for debugging) and probably busybox for as much of userspace as you can get away with. You possibly have package management from OpenEmbedded or similar, though it might just be a horrible kludged together rootfs if someone hates you. Either way it s rare for it not to involve some sort of hardware and OS much more advanced than the 8 bit machines I started out programming on. That is, unless you re playing with Arduinos or other similar hardware. I m currently waiting on some ESP8266 dev boards to arrive, but even they re quite advanced, with wifi and a basic OS framework provided. A long time ago I meant to get around to playing with PICs but never managed to do so. What I realised recently was that I have a ready made USB relay board that is powered by an ATtiny45. First step was to figure out if there were suitable programming pins available, which turned out to be all brought out conveniently to the edge of the board. Next I got out my trusty Bus Pirate, installed avrdude and lo and behold: 
$ avrdude -p attiny45 -c buspirate -P /dev/ttyUSB0
Attempting to initiate BusPirate binary mode...
avrdude: Paged flash write enabled.
avrdude: AVR device initialized and ready to accept instructions
Reading   ##################################################   100% 0.01s
avrdude: Device signature = 0x1e9206 (probably t45)
avrdude: safemode: Fuses OK (E:FF, H:DD, L:E1)
avrdude done.  Thank you.
Perfect. I then read the existing flash image off the device, disassembled it, worked out it was based on V-USB and then proceeded to work out that the only interesting extra bit was that the relay was hanging off pin 3 on IO port B. Which led to me knocking up what I thought should be a functionally equivalent version of the firmware, available locally or on GitHub. It s worked with my basic testing so far and has confirmed to me I understand how the board is set up, meaning I can start to think about what else I could do with it

26 April 2016

Jonathan McDowell: Notes on Kodi + IR remotes

This post is largely to remind myself of the details next time I hit something similar; I found bits of relevant information all over the place, but not in one single location. I love Kodi. These days the Debian packages give me a nice out of the box experience that is easy to use. The problem comes in dealing with remote controls and making best use of the available buttons. In particular I want to upgrade the VDR setup my parents have to a more modern machine that s capable of running Kodi. In this instance an AMD E350 nettop, which isn t recent but does have sufficient hardware acceleration of video decoding to do the job. Plus it has a built in fintek CIR setup. First step was finding a decent remote. The fintek is a proper IR receiver supported by the in-kernel decoding options, so I had a lot of flexibility. As it happened I ended up with a surplus to requirements Virgin V Box HD remote (URC174000-04R01). This has the advantage of looking exactly like a STB remote, because it is one. Pointed it at the box, saw that the fintek_cir module was already installed and fired up irrecord. Failed to get it to actually record properly. Googled lots. Found ir-keytable. Fired up ir-keytable -t and managed to get sensible output with the RC-5 decoder. Used irrecord -l to get a list of valid button names and proceed to construct a vboxhd file which I dropped in /etc/rc_keymaps/. I then added a 
fintek-cir * vboxhd
line to /etc/rc_maps.cfg to force my new keymap to be loaded on boot. That got my remote working, but then came the issue of dealing with the fact that some keys worked fine in Kodi and others didn t. This seems to be an issue with scancodes above 0xff. I could have remapped the remote not to use any of these, but instead I went down the inputlirc approach (which is already in use on the existing VDR box). For this I needed a stable device file to point it at; the /dev/input/eventN file wasn t stable and as a platform device it didn t end up with a useful entry in /dev/input/by-id. A quick 
udevadm info -a -p $(udevadm info -q path -n /dev/input/eventN)
provided me with the PNP id (FIT0002) allowing me to create /etc/udev/rules.d/70-remote-control.rules containing 
KERNEL=="event*",ATTRS id =="FIT0002",SYMLINK="input/remote"
Bingo, a /dev/input/remote symlink. /etc/defaults/inputlirc ended up containing: 
EVENTS="/dev/input/remote"
OPTIONS="-g -m 0"
The options tell it to grab the device for its own exclusive use, and to take all scancodes rather than letting the keyboard ones through to the normal keyboard layer. I didn t want anything other than things specifically configured to use the remote to get the key presses. At this point Kodi refused to actually do anything with the key presses. Looking at ~kodi/.kodi/temp/kodi.log I could see them getting seen, but not understood. Further searching led me to construct an Lircmap.xml - in particular the piece I needed was the <remote device="/dev/input/remote"> bit. The existing /usr/share/kodi/system/Lircmap.xml provided a good starting point for what I wanted and I dropped my generated file in ~kodi/.kodi/userdata/. (Sadly it turns out I got lucky with the remote; it seems to be using the RC-5x variant which was broken in 3.17; works fine with the 3.16 kernel in Debian 8 (jessie) but nothing later. I ve narrowed down the offending commit and raised #117221.) Helpful pages included:

18 April 2016

Jonathan McDowell: Going to DebConf 16

Going to DebConf16 Whoop! Looking forward to it already (though will probably spend it feeling I should be finishing my dissertation). Outbound: 
2016-07-01 15:20 DUB -> 16:45 LHR BA0837
2016-07-01 21:35 LHR -> 10:00 CPT BA0059
Inbound: 
2016-07-10 19:20 CPT -> 06:15 LHR BA0058
2016-07-11 09:20 LHR -> 10:45 DUB BA0828
(image stolen from Gunnar)

Jonathan McDowell: Going to DebConf 16

Going to DebConf16 Whoop! Looking forward to it already (though will probably spend it feeling I should be finishing my dissertation). Outbound: 
2016-07-01 15:20 DUB -> 16:45 LHR BA0837
2016-07-01 21:35 LHR -> 10:00 CPT BA0059
Inbound: 
2016-07-10 19:20 CPT -> 06:15 LHR BA0058
2016-07-11 09:20 LHR -> 10:45 DUB BA0828
(image stolen from Gunnar)

13 April 2016

Jonathan McDowell: Software in the Public Interest contributing members: Check your activity status!

That s a longer title than I d like, but I want to try and catch the attention of anyone who might have missed more directed notifications about this. If you re not an SPI contributing member there s probably nothing to see here Although I decided not to stand for re-election at the Software in the Public Interest (SPI) board elections last July, I haven t stopped my involvement with the organisation. In particular I ve spent some time working on an overhaul of the members website and rolling it out. One of the things this has enabled is implementation of 2009-11-04.jmd.1: Contributing membership expiry, by tracking activity in elections and providing an easy way for a member to indicate they consider themselves active even if they haven t voted. The plan is that this will run at some point after the completion of every board election. A first pass of cleanups was completed nearly a month ago, contacting all contributing members who d never been seen to vote and asking them to update their status if they were still active. A second round, of people who didn t vote in the last board election (in 2014), is currently under way. Affected members will have been emailed directly and there was a mail to spi-announce, but I m aware people often overlook these things or filter mail off somewhere that doesn t get read often. If you are an SPI Contributing member who considers themselves an active member I strongly recommend you login to the SPI Members Website and check the Last active date displayed is after 2014-07-14 (i.e. post the start of the last board election). If it s not, click on the Update link beside the date. The updated date will be shown once you ve done so. Why does pruning inactive members matter? The 2015 X.Org election results provide at least one indication of why ensuring you have an engaged membership is important - they failed to make a by-laws change that a vast majority of votes were in favour of, due to failing to make quorum. (If you re an X.org member, go vote!)

Jonathan McDowell: Software in the Public Interest contributing members: Check your activity status!

That s a longer title than I d like, but I want to try and catch the attention of anyone who might have missed more directed notifications about this. If you re not an SPI contributing member there s probably nothing to see here Although I decided not to stand for re-election at the Software in the Public Interest (SPI) board elections last July, I haven t stopped my involvement with the organisation. In particular I ve spent some time working on an overhaul of the members website and rolling it out. One of the things this has enabled is implementation of 2009-11-04.jmd.1: Contributing membership expiry, by tracking activity in elections and providing an easy way for a member to indicate they consider themselves active even if they haven t voted. The plan is that this will run at some point after the completion of every board election. A first pass of cleanups was completed nearly a month ago, contacting all contributing members who d never been seen to vote and asking them to update their status if they were still active. A second round, of people who didn t vote in the last board election (in 2014), is currently under way. Affected members will have been emailed directly and there was a mail to spi-announce, but I m aware people often overlook these things or filter mail off somewhere that doesn t get read often. If you are an SPI Contributing member who considers themselves an active member I strongly recommend you login to the SPI Members Website and check the Last active date displayed is after 2014-07-14 (i.e. post the start of the last board election). If it s not, click on the Update link beside the date. The updated date will be shown once you ve done so. Why does pruning inactive members matter? The 2015 X.Org election results provide at least one indication of why ensuring you have an engaged membership is important - they failed to make a by-laws change that a vast majority of votes were in favour of, due to failing to make quorum. (If you re an X.org member, go vote!)

12 April 2016

Reproducible builds folks: Reproducible builds: week 48 in Stretch cycle

What happened in the reproducible builds effort between March 20th and March 26th: Toolchain fixes Daniel Kahn Gillmor worked on removing build path from build symbols submitting a patch adding -fdebug-prefix-map to clang to match GCC, another patch against gcc-5 to backport the removal of -fdebug-prefix-map from DW_AT_producer, and finally by proposing the addition of a normalizedebugpath to the reproducible feature set of dpkg-buildflags that would use -fdebug-prefix-map to replace the current directory with . using -fdebug-prefix-map. Sergey Poznyakoff merged the --clamp-mtime option so that it will be featured in the next Tar release. This option is likely to be used by dpkg-deb to implement deterministic mtimes for packaged files. Packages fixed The following packages have become reproducible due to changes in their build dependencies: augeas, gmtkbabel, ktikz, octave-control, octave-general, octave-image, octave-ltfat, octave-miscellaneous, octave-mpi, octave-nurbs, octave-octcdf, octave-sockets, octave-strings, openlayers, python-structlog, signond. 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: tests.reproducible-builds.org i386 build nodes have been setup by converting 2 of the 4 amd64 nodes to i386. (h01ger) Package reviews 92 reviews have been removed, 66 added and 31 updated in the previous week. New issues: timestamps_generated_by_xbean_spring, timestamps_generated_by_mangosdk_spiprocessor. Chris Lamb filed 7 FTBFS bugs. Misc. On March 20th, Chris Lamb gave a talk at FOSSASIA 2016 in Singapore. The very same day, but a few timezones apart, h01ger did a presentation at LibrePlanet 2016 in Cambridge, Massachusetts. Seven GSoC/Outreachy applications were made by potential interns to work on various aspects of the reproducible builds effort. On top of interacting with several applicants, prospective mentors gathered to review the applications.

27 March 2016

Lunar: Reproducible builds: week 48 in Stretch cycle

What happened in the reproducible builds effort between March 20th and March 26th:

Toolchain fixes
  • Sebastian Ramacher uploaded breathe/4.2.0-1 which makes its output deterministic. Original patch by Chris Lamb, merged uptream.
  • Rafael Laboissiere uploaded octave/4.0.1-1 which allows packages to be built in place and avoid unreproducible builds due to temporary build directories appearing in the .oct files.
Daniel Kahn Gillmor worked on removing build path from build symbols submitting a patch adding -fdebug-prefix-map to clang to match GCC, another patch against gcc-5 to backport the removal of -fdebug-prefix-map from DW_AT_producer, and finally by proposing the addition of a normalizedebugpath to the reproducible feature set of dpkg-buildflags that would use -fdebug-prefix-map to replace the current directory with . using -fdebug-prefix-map. As succesful result of lobbying at LibrePlanet 2016, the --clamp-mtime option will be featured in the next Tar release. This option is likely to be used by dpkg-deb to implement deterministic mtimes for packaged files.

Packages fixed The following packages have become reproducible due to changes in their build dependencies: augeas, gmtkbabel, ktikz, octave-control, octave-general, octave-image, octave-ltfat, octave-miscellaneous, octave-mpi, octave-nurbs, octave-octcdf, octave-sockets, octave-strings, openlayers, python-structlog, signond. 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:
  • #818742 on milkytracker by Reiner Herrmann: sorts the list of source files.
  • #818752 on tcl8.4 by Reiner Herrmann: sort source files using C locale.
  • #818753 on tk8.6 by Reiner Herrmann: sort source files using C locale.
  • #818754 on tk8.5 by Reiner Herrmann: sort source files using C locale.
  • #818755 on tk8.4 by Reiner Herrmann: sort source files using C locale.
  • #818952 on marionnet by ceridwen: dummy out build date and uname to make build reproducible.
  • #819334 on avahi by Reiner Herrmann: ship upstream changelog instead of the one generated by gettextize (although duplicate of #804141 by Santiago Vila).

tests.reproducible-builds.org i386 build nodes have been setup by converting 2 of the 4 amd64 nodes to i386. (h01ger)

Package reviews 92 reviews have been removed, 66 added and 31 updated in the previous week. New issues: timestamps_generated_by_xbean_spring, timestamps_generated_by_mangosdk_spiprocessor. Chris Lamb filed 7 FTBFS bugs.

Misc. On March 20th, Chris Lamb gave a talk at FOSSASIA 2016 in Singapore. The very same day, but a few timezones apart, h01ger did a presentation at LibrePlanet 2016 in Cambridge, Massachusetts. Seven GSoC/Outreachy applications were made by potential interns to work on various aspects of the reproducible builds effort. On top of interacting with several applicants, prospective mentors gathered to review the applications. Huge thanks to Linda Naeun Lee for the new hackergotchi visible on Planet Debian.

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