I am led to believe that splunkd (some agent for feeding log entries into the Grand Log Analysis Tool Of Our Age ) has no capability for running itself in the foreground. This is stupid. Do not make these sorts of assumptions about how the user will want to run your software. Some people use sane service-management systems that are capable of handling the daemonisation for you and automatically restart the managed process on crash. These systems are typically much easier to configure and debug, and they don t need bloody PID files and the arguments about where to put them (tmpfs, inside or outside chroots oh my) and who should update them and how to reliably detect that they re out of date when they crash without causing race conditions and whether non-root-running processes should place their PID files in the same place and how do you deal with the permissions issues and bugger that for a game of skittles. In short, if you provide a service daemon and do not provide some well-documented means of saying don t background , I will hurt you. This goes double if your shitware is not open source.

Disclaimer I'm no symbol expert and dealing with symbol files for first time from the time I started packaging. What I did here is depending on some suggestions I got in #debian-mentors. If you think what I did was wrong please enlighten me :-). Problem Recently 2 of my library packages pugixml and ctpp2 got accepted into Debian archive and when buildd tried to build them on remaining architectures other than one for which I uploaded (amd64) builds failed. This was expected as symbols file which I generated was for amd64. As usual I got 2 serious bug reports #704718 and #705135. Solution First I was not sure how to handle this. I read article on symbols files handling by rra [1] and tried to use pkgkde-symbolshelper tool only to quickly figure out that I need to use pkgkde_symbolshelper addon for dh sequencer. But this was not possible for me as I was using CDBS for packaging. I did a quick chat on #debian-mentors and some one suggested me to tag symbols which vary across architecture with (c++) tag. First I was not sure but after reading dpkg-gensymbols man page understood that I need to replace the entire mangled symbols lines with de-mangled version tagged with (c++) in the beginning. But this was hectic job searching for each deleted symbols and replacing it. So I thought of writing a script to do the job and after struggling for 3 days (yeah I was bit dumb that I didn't read manual date: "2013-04-14 18:39:20 +0530" pugixml and ctpp2 package using it, which is now waiting for Jonas for uploading it. Here is the script So basically to make this work we need all buildlogs to be downloaded from buildd's again this was easy thanks to rra for developing pkgkde-getbuildlogs :-). Once you have build logs directory run the above script as follows

cppsymbol_replace.sh path_to_buildlogs path_to_symbol_file upstream_version

After replacing symbols I tried to build package on i386 chroot and build passed successfully but lintian told me that there are symbols which have Debian version appended to it and this might lead to date: "2013-04-14 18:42:42 +0530" back to mentors :-). It is this time I really understood concept of mangled names generated by compiler and why it vary across the architecture ;-). This time some one by nick pochu suggested me to pass option -v with package version to dpkg-gensymbols to make it generate symbols with package version and not Debian version. The following probably needs to be done if package uses dh sequencer but I'm not sure as I've not tested it. If wrong please correct me. If you are using CDBS this is pretty simple. Just add following to rules I noticed that when I provide (c++) tagged de-mangled name dpkg-gensymbols simply replaces it with proper mangled name but the deletion doesn't trigger an error in dpkg-gensymbols. This script me allowed to replace 128 symbols which were very tricky and long with de-mangled and tagged version in ctpp2, so I hope it should work across different packages without any problem. Only silly mistake I did was occurrence of & symbol in function making sed go mad which I took one full day to debug :facepalm:. So that's it folks, if you see something wrong in what I did please let me know through the comments. [1] http://www.eyrie.org/~eagle/journal/2012-01/008.html

The Debian Project Leader election has concluded and the winner is Lucas Nussbaum. Of a total of 988 developers, 390 developers voted using the Condorcet method. More information about the result is available in the Debian Project Leader Elections 2013 page. The new term for the project leader will start on April 17th and expire on April 17th 2014.

Hy s got a new home (and team!) As some of you interested folks know, I ve been hacking on Hy, and I m proud to announce it s new home at hylang.org and future deb repo at gethy.org. I ve posted this as an image for one very important reason - Hy is now a full community based project. There s been in insane reaction to hy, and I d like to keep it sustainable. So, come hack with us on #hy on freenode, or just help us come up with more puns. As always, try hy, and see if you don t have some feature requests!

You might of looked at Ralph Bean s tutorial on graphs and thought, that s nice but I d like something different. The great thing about ToscaWidgets using the jqPlot library is that pretty much anything you can do in jqPlot, you can do in ToscaWidgets and by extension in TurboGears. You want different graph types? jqPlot has heaps! My little application needed a Pie Chart to display the overall status of attributes. There are 6 states an attribute can be in: Up, Alert, Down, Testing, Admin Down and Unknown. The Pie Chart would show them all with some sort of colour representing the status. For this example I ve used hard-coded data but you would normally extract it from the database using a TurboGears model and possibly some bucket sorting code. I ve divided my code into widget specific, which is found in myapp/widgets/attribute.py and the controller code found unsurprisingly at myapp/controllers/attribute.py Also note that some versions of ToscaWidgets have a bug which means any jqPlot widget won t work, version 2.0.4 has the fix for issue 80 that explains briefly the bug. The widget code looks like this: Some important things to note are:

• resources are the way of pulling in the javascript includes that actually do the work, generally if you have something like a renderer using js_symbol further on, it needs to be listed in the resources too.
• seriesColors is how you make a specific data item a specific colour, or perhaps change the range of colours. It s not required if you use the default set, which is defined in the jqPlot options.
• The renderer tells jqPlot what sort of graph we want, the line above says we want pie

Next the controller needs to be defined: And that is about it, we now have a controller path attributes/statuspie which shows us the pie chart.
My template is basically a bare template with a $ w.display n in it to just show the widget for testing.

DRI3K First Steps Here s an update on DRI3000. I ll start by describing what I ve managed to get working and then summarize discussions that happened on the xorg-devel mailing list. Private Back Buffers One of the big goals for DRI3000 is to finish the job of moving buffer management out of the X server and into applications. The only thing still allocated by DRI2 in the X server are back buffers; everything else moved to the client side. Yes, I know, this breaks the GLX requirement for sharing buffers between applications, but we just don t care anymore. As a quick hack, I figured out how to do this with DRI2 today allocate our back buffers separately by creating X pixmaps for them, and then using the existing DRI2GetBuffersWithFormat request to get a GEM handle for them. Of course, now that all I ve got is a pixmap, I can t use the existing DRI2 swap buffer support, so for now I m just using CopyArea to get stuff on the screen. But, that works fine, as long as you don t care about synchronization. Handling Window Resize The biggest pain in DRI2 has been dealing with window resize. When the window resizes in the X server, a new back buffer is allocated and the old one discarded. An event is delivered to invalidate the old back buffer, but anything done between the time the back buffer is discarded and when the application responds to the event is lost. You can easily see this with any GL application today resize the window and you ll see occasional black frames. By allocating the back buffer in the application, the application handles the resize within GL; at some point in the rendering process the resize is discovered, and GL creates a new buffer, copies the existing data over, and continues rendering. So, the rendered data are never lost, and every frame gets displayed on the screen (although, perhaps at the wrong size). The puzzle here was how to tell that the window was resized. Ideally, we d have the application tell us when it received the X configure notify event and was drawing the frame at the new size. We thought of a cute hack that might do this; track GL calls to change the viewport and make sure the back buffer could hold the viewport contents. In theory, the application would receive the X configure notify event, change the viewport and render at the new size. Tracking the viewport settings for an entire frame and constructing their bounding box should describe the size of the window; at least it should describe the intended size of the window. There s at least one serious problem with this plan applications may well call glClear before calling glViewport, and as glClear does not use the current viewport, instead clearing the whole window, we couldn t use the viewport as an indication of the current window size. However, what this exercise did lead us to realize was that we don t care what size the window actually is, we only care what size the application thinks it is. More accurately, the GL library just needs to be aware of any window configuration changes before the application, so that it will construct a buffer that is not older than the application knowledge of the window size. I came up with two possible mechanisms here; the first was to construct a shared memory block between application and X server where the X server would store window configuration changes and signal the application by incrementing a sequence number in the shared page; the GL library would simply look at the sequence number and reallocate buffers when it changed. The problem with the shared memory plan was that it wouldn t work across the network, and we have a future project in mind to replace GLX indirect rendering with local direct rendering and PutImage which still needs accurate window size tracking. More about that project in a future post though X Events to the Rescue So, I decided to just have the X server send me events when the window size changed. I could simply use the existing X configure notify events, but that would require a huge infrastructure change in the application so that my GL library could get those events and have the application also see them. Not knowing what the application is up to, we d have to track every ChangeWindowAttributes call and make sure the event_mask included the right bits. Ick. Fortunately, there s another reason to use a new event we need more information than is provided in the ConfigureNotify event; as you know, the Swap extension wants to have applications draw their content within a larger buffer that can have the window decorations placed around it to avoid a copy from back buffer to window buffer. So, our new ConfigureNotify event would also contain that information. Making sure that ConfigureNotify event is delivered before the core ConfigureNotify event ensures that the GL library should always be able to know about window size changes before the application. Splitting the XCB Event Stream Ok, so I ve got these new events coming from the X server. I don t want the application to have to receive them and hand them down to the GL library; that would mean changing every application on the planet, something which doesn t seem very likely at all. Xlib does this kind of thing by allowing applications to stick themselves into the middle of the event processing code with a callback to filter out the events they re interested in before they hit the main event queue. That s how DRI2 captures Invalidate events, and it works , but using callbacks from the middle of the X event processing code creates all kinds of locking nightmares. As discussed above, I don t care when GL sees the configure events, as long as it gets them before the application finds about about the window size change. So, we don t need to synchronously handle these events, we just need to be able to know they ve arrived and then handle them on the next call to a GL drawing function. What I ve created as a prototype is the ability to identify specific events and place them in a separate event queue, and when events are placed in that event queue, to bump a sequence number so that the application can quickly identify that there s something to process. Making the Event Mask Per-API Instead of Per-Client The problem described above about using the core ConfigureNotify events made me think about how to manage multiple APIs all wanting to track window configuration. For core events, the selection of which events to receive is all based on the client; each client has a single event mask, and each client receives one copy of each event. Monolithic applications work fine with this model; there s one place in the application selecting for events and one place processing them. However, modern applications end up using different APIs for 3D, 2D and media. Getting those libraries to cooperate and use a common API for event management seems pretty intractable. Making the X server treat each API as a separate entity seemed a whole lot easier; if two APIs want events, just have them register separately and deliver two events flagged for the separate APIs. So, the new DRI3 configure notify events are created with their own XID to identify the client-side owner of the event. Within the X server, this required a tiny change; we already needed to allocate an XID for each event selection so that it could be automatically cleaned up when the client exited, so the only change was to use the one provided by the client instead of allocating one in the server. On the wire, the event includes this new XID so that the library can use it to sort out which event queue to stick the event in using the new XCB event stream splitting code. Current Status The above section describes the work that I ve got running; with it, I can run GL applications and have them correctly track window size changes without losing a frame. It s all available on the dri3 branches of my various repositories for xcb proto, libxcb, dri3proto and the X server. Future Directions The first obvious change needed is to move the configuration events from the DRI3 extension to the as-yet-unspecified new Swap extension (which I may rename as Present , as in please present this pixmap in this window ). That s because they aren t related to direct rendering, but rather to tracking window sizes for off-screen rendering, either direct, indirect or even with the CPU to memory. DRI3 and Fences Right now, I m not synchronizing the direct rendering with the CopyArea call; that means the X server will end up with essentially random contents as the application may be mid-way through the next frame before it processes the CopyArea. A simple XSync call would suffice to fix that, but I want a more efficient way of doing this. With the current Linux DRI kernel APIs, it is sufficient to serialize calls that post rendering requests to the kernel to ensure that the rendering requests are themselves serialized. So, all I need to do is have the application wait until the X server has sent the CopyArea request down to the kernel. I could do that by having the X server send me an X event, but I think there s a better way that will extend to systems that don t offer the kernel serialization guarantee. James Jones and Aaron Plattner put together a proposal to add Fences to the X Sync extension. In the X world, those offer a method to serialize rendering between two X applications, but of course the real goal is to expose those fences to GL applications through the various GL sync extensions (including GLARBsync and GLNVfence). With the current Linux DRI implementation, I think it would be pretty easy to implement these fences using pthread semaphores in a block of memory shared between the server and application. That would be DRI-specific; other direct rendering interfaces would use alternate means to share the fences between X server and application. Swap/Present The Second Extension By simply using CopyArea for my application presentation step, I think I ve neatly split this problem into manageable pieces. Once I ve got the DRI3 piece working, I ll move on to fixing the presentation issue. By making that depend solely on existing core Pixmap objects as the source of data to present, I can develop that without any reference to DRI. This will make the extension useful to existing X applications that currently have only CopyArea for this operation. Presentation of application contents occurs in two phases; the first is to identify which objects are involved in the presentation. The second is to perform the presentation operation, either using CopyArea, or by swapping pages or the entire frame buffer. For offscreen objects, these can occur at the same time. For onscreen, the presentation will likely be synchronized with the scanout engine. The second form will mean that the Fences that mark when the presentation has occurred will need to signaled only once the operation completes. A CopyArea operation means that the source pixmap is ready immediately after the Copy has completed. Doing the presentation by using the source pixmap as the new front buffer means that the source pixmap doesn t become ready until after the next swap completes. What I don t know now is whether we ll need to report up-front whether the presentation will involve a copy or a swap. At this point, I don t think so the application will need two back buffers in all cases to avoid blocking between the presentation request and the presentation execution. Yes, it could use a fence for this, but that still sticks a bubble in the 3D hardware where it s blocked waiting for vblank instead of starting on the next frame immediately. Plan of Attack Right now, I m working on finishing up the DRI3 piece:

• Replace the DRI2 buffer allocation kludge with actual local buffer allocation, mapping them into pixmaps using FD passing.
• Replace the DRI2 authentication scheme with having the X server open the DRI object, preparing it for rendering and passing it back to the application.
• Working on the XCB pieces to get the split event-queue stuff landed upstream.
• Implementing the Fencing stuff to correctly serialize access to the pixmap.

The first three seem fairly straight forward. The fencing stuff will involve working with James and Aaron to integrate their XSync changes into the server. After that, I ll start working on the presentation piece. Foremost there is figuring out the right name for this new extension; I started with the name Swap as that s the GL call it implements. However, Swap is quite misleading as to the actual functionality; a name more like Present might provide a better indication of what it actually does. Of course, Present is both a verb and a noun, with very different connotations. Suggestions on this most complicated part of the project are welcome!

I ve been working on maintaining lecture slides and a manual, by writing a single source org-mode file. From a single source I want to be able to generate different output PDFs, only changing a few switches :

• slides deck
• a manual document
• source files for examples

The slides may contain notes. Here s an archive that contains an example document and complementary files. See this documentation document for more details (itself maintained with such an .org source).

I need to write up new Kindle books, of which there are now quite a few due to various sales plus the Hugo nominee slate, but I got another set of paper books and they're sitting in front of me. So here's a list. Saladin Ahmed Throne of the Crescent Moon (sff)
Elizabeth Bear Shattered Pillars (sff)
Ta-Nehisi Coates The Beautiful Struggle (non-fiction)
Guy Gavriel Kay River of Stars (sff)
Jenny Larson Let's Pretend This Never Happened (non-fiction)
Domenica Ruta With or Without You (non-fiction)
Jay Wexler The Odd Clauses (non-fiction) Ahmed's book is the remaining Hugo nominee that I didn't already pick up. I'm delighted to see the diversity on the Hugo and particularly the Nebula slate this year, and I'm curious to see the spin that Ahmed brings to the epic fantasy genre. Bear's book is the sequel to Range of Ghosts, another book I'm very much looking forward to reading to but haven't yet. I'm rather behind on reading Bear's work right now. Let's Pretend This Never Happened, With or Without You, and The Beautiful Struggle are all memoirs, of varying degrees of seriousness. I've gotten hooked on Coates's writing at The Atlantic, and I highly recommend it if you've not yet seen it. Domenica Ruta's memoir is the latest Indiespensible selection. Jay Wexler's book was recommended by Lowering the Bar, a legal humor blog whose entire archives I'm slowly reading. But the highlight of this order is Kay's River of Stars, which is a sequel of sorts to one of my favorite books ever. This is probably the book I'll read during my next vacation.

Review: Familiar, by J. Robert Lennon

Publisher:	Greywolf
Copyright:	2012
ISBN:	1-55597-535-6
Format:	Hardcover
Pages:	205

This is the first book of an experiment. I'm fairly well-read in science fiction and fantasy and increasingly well-read in non-fiction of interest (although there's always far more of that than I'll get to in a lifetime), but woefully unfamiliar with what's called "mainstream" literature. Under the principal that things people are excited about are probably exciting, I've wanted to read more and understand the appeal. Powell's, which I like to support anyway, has a very nice (albeit somewhat expensive) book club called Indiespensable, which sends its subscribers very nice editions of new works that Powell's thinks are interesting, with a special focus on independent publishers. So I signed up and hope to stick with it for at least a year. (The trick will be fitting these books in amongst my regular reading.) Familiar is the first feature selection I received. Elisa Brown is a mother with a dead son and a living one, a failing marriage, an affair, and a life that is, in short, falling apart. Then, while driving back from her annual pilgrimage from her son's grave, the world seems to twist and change. She finds herself dressed for business, wearing a nametag and apparently coming back from a work-related convention, driving a car that's entirely unfamiliar to her. When she gets home, everything else has changed too: her marriage seems to be on firmer ground, but based on rules she doesn't understand. She has a different job, different clothes, a different body in some subtle ways. And both of her sons are alive. I'm going to have to have a long argument with myself about where to (meaninglessly) categorize this on my review site, since in construction it is an alternate reality story and therefore a standard SF trope. Any SF reader is going to immediately assume Elisa has somehow been transported into an alternate reality with a key divergence point from her own. But that's not Lennon's focus. He stays ambiguous on the question of whether this is really happening or whether Elisa had some sort of nervous breakdown, and while some amount of investigation of the situation does take place, it's the sort of investigation that an average person with no access to special resources or scientific knowledge and a completely unbelievable story would be able to do: Internet conspiracy chatrooms and some rather dodgy characters. The focus is instead on Elisa's reaction to the situation, her choices about how to treat this new life, and on how she processes her complex emotions about her family and herself. I had profoundly mixed feelings about this book when I finished it, and revisiting it to review it, I still do. The writing is excellent: spare, evocative, and enjoyable to read. Lennon has a knack for subjective description of emotion and physical experience. The reader feels Elisa's deep discomfort with her changed body and her changed car, her swings between closed-off emotions and sudden emotional connection with a specific situation, and her struggle with the baffling question of how to come to terms with a whole new life. The part of the book from about the middle to nearly the end is excellent. Video games make an appearance and are handled surprisingly well. And when Elisa starts being blunt with people, I found myself both liking her and caring about what happens to her. On the other hand, Familiar also has some serious problems, and one of the biggest is the reaction I feared I'd have to mainstream literature: until Elisa started opening up and taking action, I found it extremely difficult to care about anyone in this book. They're all so profoundly petty, so closed off and engrossed in what seem like depressing and utterly boring lives. I'm sure that some of this is intentional and is there to lay the groundwork for Elisa's own self-discovery, but even towards the end of that self-discovery, everything here is so relentlessly middle-class suburbia that I felt stifled just reading about it. I think it's telling that no one in this book ever seems to have any substantial problem with money, or even with work. Elisa walks into a job that she's never done before and within a few weeks is doing it so well that she can take large amounts of time to wander around for plot purposes. This is a book about highly privileged people being miserable in a bubble. While those people certainly do exist, and I can believe that they act like this, I'm not sure how much I want to read about them. Thankfully, the plot does lead Elisa to poke some holes in that bubble, if never get out of it entirely. This is also another one of those stories in which every character has massive communication problems. Now, this deserves some caveats: Elisa's communication problems with her husband are part of the problem that starts the book and are clearly intentional, as are her communication difficulties with her children. And she's not really close enough to anyone to confide in them. But even with those caveats, no one in this book really talks to anyone else. It's amazing that anyone forms any connections at all, given how many walls and barriers they have around themselves. As someone with a bit of a thing for communication, this drove me nuts to read about, particularly in the first half of the book. But the worst problem is that Lennon completely blows the ending. And by that I don't just mean that I disliked the ending. I mean the ending is so unbelievable and so contrary to the entire rest of the book, at least the way I was reading and understanding it, that I think Familiar is a much better novel if you just remove the final scene entirely. It was such a bizarre and unnecessary twist that I found it infuriating. I don't want to spoil an ending, even a bad ending, so I'll only say this: it felt to me like Lennon just wasn't comfortable with his setting and plot driver and couldn't leave it alone. I think an experienced SF author wouldn't have made this mistake. There were two obvious possible conclusions to draw from the setting, plus a few interesting combinations, and I think someone comfortable with this sort of alternate reality story would have taken one of those options, any of which would have been a reasonable dismount for the plot. Alternately, they could have left it entirely ambiguous to the end and explored why the explanation may not actually matter. But Lennon seemed to me to have a tin ear for plausibility and for the normal flow of this sort of story and seems to have taken it as license for arbitrary events, thus completely violating the internal consistency and emergent rules that he'd spent the rest of the book building. I've mostly talked about my reactions to the characters and the writing and have not said much about the plot. That's somewhat intentional, since figuring out where the story will go is one of the best parts of this book. It's surprisingly tense and well-crafted for not having that much inherent dramatic tension. The excellent writing kept me reading through the first part, when I hated everyone in the story, and then Elisa started taking responsibility for her own life and actions and I started really enjoying the book while being constantly surprised. I think it's the sort of story that's best to take without too much foreknowledge of where it's going. I'm going to call this first experiment a qualfied success. Familiar was certainly interesting to read, and quite different from what I normally read despite the SF premise. If it weren't for the ending, I'd be recommending it to other people. Rating: 6 out of 10

Keith and I have discovered a change in the behavior of the protection circuits integrated in the LiPo batteries we sell for use with Altus Metrum products that poses a risk for our customers. This post is meant to document what we now know, communicate changes we're planning as a result, and explain what we think flyers of our existing electronics and batteries may want to do to maximize their chances of successful flights. Background Choosing batteries and designing pyro circuits for high power rocketry avionics involves a variety of trade-offs. Reliability is the highest concern, both because nobody wants to lose an airframe due to a failed pyro event, and also because airframes recovering anomalously have safety implications. But we also care about other factors including cost and weight, and usually want to minimize the complexity of both the electronics and the overall installation. The objective of a pyro circuit is to dump enough energy rapidly into an electric match to cause it to catch fire. We need batteries both to power the electronics that decide when to fire the charge, and to provide the energy that actually ignites the match. The two most common battery types seen in the rocketry hobby are alkaline cells, often the nominal 9V rectangular variety, and rechargeable batteries based on Lithium Polymer (LiPo) chemistry. LiPo cells are 3.7 volts per cell nominal voltage, are very light, and have a high energy density. LiPo capacity is measured in units of current times time, so an 850mAh cell should be able to deliver 850 milliamps for an hour. The battery industry also uses something called a "C rate" to describe how fast the battery can be usefully discharged, wich is a multiplier relative to the battery capacity. So a battery with 850mAh capacity and a "2C" rating can deliver current at a sustained rate of 1700mA until discharged, while the same capacity at a "5C" rating can deliver 4250mA. By comparison, most 9V alkaline batteries are actually composed of 6 individual 1.5V cells enclosed in a wrapper. It's hard to get hard numbers for capacity and discharge rate, since in an alkaline cell the two are not independent, and the discharge rate is related to the volume of each individual cell. The data sheet for an Energizer 522 shows just over 600mAh at a 25mA discharge rate, dropping to about 300mAh at a 500mA discharge rate. Importantly for use in pyro circuits, LiPo cells have a very low source impedance, which means they can source immense amounts of current. It's not unusual for cells in the 1000mAh range to have ratings in excess of 30C! Because this rapid discharge ability can pose a risk of fire, it's common for LiPo cells to come with a "protection board" integrated into the battery assembly that is designed to limit the current to some rate such as 2C continuous duty. In large airframes, or projects that involve staging, air-starts, or other complex pyro event sequences, the most reliable approach will always be to use separate batteries for the control electronics and the source of pyro firing power. In the limit, having separate pyro batteries for each pyro charge with the control electronics only providing the switching to connect the batteries to the charges could even make sense. But for most airframes, this is overkill, and the increases in mass, volume, and wiring complexity just don't make sense. The challenge, then, is how to design electronics that will robustly initiate pyro events without negatively affecting the rest of the electronics when operating from a single shared battery. Altus Metrum Pyro Circuits The very first prototypes of TeleMetrum were designed to use a single-cell LiPo battery, and had an on-board 100mA charging circuit. Because we needed 5 volts to power the accelerometer, we had a small switching regulator that up-converted the LiPo voltage, and we used some of that regulator's output to charge a 1000uF capacitor. The pyro circuit used Fairchild FDN335N N-channel MOSFET switches in a low-side switching configuration to dump the energy stored in the capacitor through an attached ematch. Those FETs had an on resistance of under a tenth of an ohm in our operating conditions. The circuit worked very reliably, but the 1000uF electrolytic cap was huge and we struggled with the mechanics of such a large part hanging off the board... It turns out that 3.7 volts is way more than enough to fire a typical low-current e-match or equivalents like the Quest Q2G2 igniters. In fact, bench testing with a good digital oscilloscope showed that a typical e-match with resistance of 1.3-1.8 ohms will fire in approximately 13 microseconds when hit with the nominal 3.7 volts from a LiPo. So, starting with our v0.2 boards, we switched to using the LiPo battery voltage directly to fire the pyro charges, eliminating the clunky electrolytic capacitor entirely. We also switched to the Fairchild FDS9926A dual N-channel MOSFET whose specs are better in all regards for our application. The on resistance is down around 40 milli-ohms in our circuit, such that the current ratings are much higher (FET current limits are primarily driven by how much heat is generated due to current flowing through the channel's on resistance). Because using the LiPo voltage directly means we're effectively temporarily putting a very low resistance across the battery during the pyro events, the input voltage to the voltage regulator gets pulled down. To ensure the processor could "ride through" these events, we added a 100uF surface mount bulk capacitor on the 3.3 volt regulated voltage rail, which bench testing demonstrated was more than sufficient to maintain processor operation through pyro events. And that is essentially the same pyro circuit on all the boards, both TeleMetrum and TeleMini, that we have shipped to date. What's Changed The LiPo batteries we source and sell with our electronics come with a protection board and cable terminated in a 2-pin, 2mm "JST" connector. The specs on the protection board have always been "2C continuous", but we observed the ability to source much higher currents for short periods such as the 13 micro-seconds or so required to fire an e-match. Thus these protection circuits seemed just fine .. we could fire e-matches with a burst of current but were protected against short circuits in the wiring or our boards by the 2C continuous limit. Unfortunately, the most recent batch of batteries we sourced seem to have a much "twitchier" protection circuit. We can draw more than 2C for short bursts, but not as much as with prior boards, and not for as long an interval. With a 1 ohm power resistor on the pyro terminals of one of our boards, we get about 9 milliseconds of power before the protection circuit cuts in and shuts the battery down. The power stays down until all load is removed, which at least means the board is turned off and back on again, and in some cases could even mean the battery is unplugged and re-plugged since we draw trace current to keep the GPS memory alive even when the power is turned off, and at least some of the new batteries see that as enough to keep the power turned off after an over-current event. For many e-matches, this isn't an issue, since 9 milliseconds is way longer than the 13 microseconds needed to fire the charge. Unfortunately, we've discovered that many of the e-matches bought and used in the rocketry hobby are actually made for use in the fireworks industry, where it is desireable to retain continuity after firing so that series connections of e-matches all can fire even if some fire faster than others! This means that while the resistance goes up some after firing, sometimes the drain on the battery remains sufficient to cause the protection circuit to kick in even after the pyro charge has fired. What We're Doing About It If we remove the protection circuit from the LiPo (or jumper around it), all existing Altus Metrum products will operate successfully with pyro charges thave have an effective resistance of as low as 1 ohm. That's lower than any e-match or Q2G2 we've ever seen, so in effect what this means is that if you have an existing Altus Metrum flight computer, and you remove the LiPo protection circuit, you're good to go. This does not really make things any more "dangerous", since our battery chargers are all current limited and our discharge patterns will never cause heating of the battery. Frankly, in a rocket, the most likely way to cause a problem with a LiPo is by smashing or puncturing the actual battery during bench work or during a crash... and those cause the same problems with or without a protection board present. In the future, we will ship batteries that have either a much higher C rating on the protection circuit, or have no protection circuit at all. The number of problems reported by actual customers that we think should be attributed to LiPo protection circuit boards is very low, and we suspect most of our customers who are happily flying their boards can continue to do so. Ground testing where you fire pyro charges (or at least e-matches) using RF to issue the commands (not USB, since the LiPo charger is running any time USB is connected!) will confirm whether there's a problem. If the board resets (does startup beeps) after a pyro event, or shuts down completely (no LED activity), then you have a problem. If the matches light and the board keeps running, you're good to go. However, any Altus Metrum customer with LiPo batteries sourced from us or our distributors who is worried about this problem (even if you haven't seen problems in ground testing or previous flights), and who doesn't want to try soldering on the battery circuit board yourself, is welcome to contact us about removing the protection circuit for you. We won't charge anything other than shipping. To take advantage of this offer, just send email to fixmybattery@altusmetrum.org telling us how many of which capacity batteries you have that you'd like updated, and we'll respond with an RMA number and shipping details. Going Even Further As previously indicated, with the LiPo protection circuits removed, all of our current products will work reliably with at least 1 ohm across the pyro terminals. That should cover all real-world flying conditions just fine, but we're not satisfied yet. We've designed a new pyro control circuit that transfers the maximum possible energy to the load regardless of battery voltage without ever allowing the voltage to the processor to droop at all. We're testing this new circuit in various prototypes now, and if it pans out it will probably show up first in MegaMetrum and then trickle down to TeleMetrum and TeleMini as those products are updated later this year. The new pyro circuit tolerates 0 ohms (dead shorts) on the pyro terminals for as long as the battery can provide current, which is as good as it gets. We think the circuit is clever enough that we'll probably write more about it once we're finished validating it.

The Google Summer of Code is a program that allows post-secondary students aged 18 and older to earn a stipend writing code for Free and Open Source Software projects during the summer. For the eighth time, Debian has just been accepted as a mentoring organization for this year's program. If you're an eligible student, now is the time to take a look at our project ideas list, engage with the mentors for the projects you find interesting, and start working on your application!
Please read the FAQ and the Program Timeline on Google's website. If you are interested, we encourage you to come and chat with us on irc (#debian-soc on irc.oftc.net), or to send an email to the SoC coordination mailing-list. Most of the GSoC related information in Debian can be found on our wiki pages, but feel free to ask us directly on irc or via email. We're looking forward to work with amazing students again this summer!

I bought a ScanJet N6350 a few years back, in the belief that it would work. After all, you write free Linux drivers for all your printers, and when those printers are multifunctional printers with scanners, you do make sure the scanner bits of those printers work too. So it shouldn't be too hard to write a Linux driver for that scanner too, right? Apparently it is. For some reason that I can't imagine, you decided that my money is worth more than my stress levels.

• The HP ScanJet N6350 is a combination USB/network scanner. That's great; I don't need it to be right next to my laptop all the time. Having the ability to get it sent to me by email (as your product page claims it can do) reduces my workload. Unfortunately, what you didn't mention on the product page is that the scanner is pretty dumb; it does network, yes, but the only way in which it can send emails is by using some application running on a system on the other end of the network connection. That's pretty silly. It wouldn't be so bad, however, except...
• ... the system on the other end of the network connection has to be running Windows. That's right, you didn't write a Linux driver for some reason. You also didn't publish the network protocol, and even the USB connection seems undocumented. So I can't use Linux to scan my documents. It wouldn't be so bad, however, since I already have a Windows XP virtual machine lying around somewhere, mainly because there's this satellite navigation system builtin to my car that also requires it; I just installed your scanners oftware on that machine, and I can scan. Except...
• ... whenever an error occurs in the scanning process, the UI locks up completely. I can't retry the last page that I was trying to scan, and often I can't even save the document anymore, either; I have to rescan the whole document. That wouldn't be so bad, except...
• ... the ADF is total crap. If I put more than a few pages on the feeder, and they've got some horizontal folds in them (as is likely with snail mail that came out of an envelope), I'm very likely to end up with a paper jam, or with multiple pages sucked into the feeder at once, causing an error and a loss of my scanned document. That wouldn't be so bad, except...
• ... the process for finishing one scan and starting the next involves stopping and starting your whole scanning software, which takes a rather long time. As such, I'd prefer to just scan a whole stack of incoming snail mail in one go, and then use pdfsam to split up the PDF file. But then I have to babysit the scanning process so that I don't get any errors; but I fail at that about as often as I succeed, meaning, it usually takes a long time to get through the stack.

Dear HP, you suck. I fail to understand how the basic loss of functionality after a failed scan managed to get through your testing. I fail to understand why you think Linux users should be able to print, but not scan. And I especially fail to understand why I should waste my time with such an expensive device that can't even perform its basic functionality with more than 10% success rate.

phpMyAdmin has been accepted for Google Summer of Code 2013. So if you are a student and thinking about how to spend this summer, you might want to join us. This year we will have fresh mentor blood and we have prepared dozen of ideas, so in case you are interested, it's really the time to start to work on your application. We require you to contribute before GSoC, so that we can see you can handle the code and our tools. All details you might need are available in our applicant guide. Our requirements might sound strict, but without them, we would drown in hundredths of applications with no clue how to decide, so do your homework and prepare perfect application. If you have any questions, get in touch with us on mailing list and get ready for April 22th, when you can submit the application.

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Hello everyone! I am very excited to report about the awesome progress we made with Tanglu, the new Debian-based Linux-Distribution. First of all, some off-topic info: I don t feel comfortable with posting too much Tanglu stuff to Planet-KDE, as this is often not KDE-related. So, in future Planet-KDE won t get Tanglu information, unless it is KDE-related You might want to take a look at Planet-Tanglu for (much) more information. So, what happened during the last weeks? Because I haven t had lectures, I nearly worked full-time on Tanglu, setting up most of the infrastructure we need. (this will change with the next week, where I have lectures again, and I also have work to do on other projects, not just Tanglu ^^) Also, we already have an awesome community of translators, designers and developers. Thanks to them, the Tanglu-Website is now translated to 6 languages, more are in the pipeline and will be merged later. Also, a new website based on the Django framework is in progress. The Logo-Contest We ve run a logo-contest, to find a new and official Tanglu logo, as the previous logo draft was too close to the Debian logo (I asked the trademark people at Debian). More than 30 valid votes (you had to be subscribed to a Tanglu Mailinglist) were received for 7 logo proposals, and we now have a final logo: I like it very much Fun with dak I decided to use dak, the Debian Archive Kit, to handle the Tanglu archive. Choosing dak over smaller and easy-to-use solutions had multiple reasons, the main reason is that dak is way more flexible than the smaller solution (like reprepro or min-dak) and able to handle the large archive of Tanglu. Also, dak is lightning fast. And I would have been involved with dak sooner or later anyway, because I will implement the DEP-11 extension to the Debian Archive later (making the archive application-friendly). Working with dak is not exactly fun. The documentation is not that awesome, and dak contains many hardcoded stuff for Debian, e.g. it often expects the unstable suite to be present. Also, running dak on Debian Wheezy turned out to be a problem, as the Python module apt_pkg changed the API and dak naturally had problems with that. But with the great help of some Debian ftpmasters (many thanks to that!), dak is now working for Tanglu, managing the whole archive. There are still some quirks which need to be fixed, but the archive is in an usable state, accepting and integrating packages. The work on dak is also great for Debian: I resolved many issues with non-Debian dak installations, and made many parts of dak Wheezy-proof. Also, I added a few functions which might also be useful for Debian itself. All patches have of course been submitted to upstream-dak. Wanna-build and buildds This is also nearly finished Wanna-build, the software which manages all buildds for an archive, is a bit complicated to use. I still have some issues with it, but it does it s job so far. (need to talk to the Debian wanna-build admins for help, e.g. wanna-build seems to be unable to handle arch:all-only packages, also, build logs are only submitted in parts) The status of Tanglu builds can be viewed at the provisoric Buildd-Status pages. Setting up a working buildd is also a tricky thing, it involves patching sbuild to escape bug #696841 and applying various workarounds to make the buildd work and upload packages correctly. I will write instructions how to set-up and maintain a buildd soon. At time, we have only one i386 buildd up and running, but more servers (in numbers: 3) are prepared and need to be turned into buildds. After working on Wanna-build and dak, I fully understand why Canonical developed Launchpad and it s Soyuz module for Ubuntu. But I think we might be able to achieve something similar, using just the tools Debian already uses (maybe a little less confortable than LP, but setting up an own LP instance would have been much more trouble). Debian archive import The import of packages from the Debian archive has finished. Importing the archive resulted in many issues and some odd findings (I didn t know that there are packages in the archive which didn t receive an upload since 2004!), but it has finally finished, and the archive is in a consistent state at time. To have a continuous package import from Debian while a distribution is in development, we need some changes to wanna-build, which will hopefully be possible. Online package search The Online-Package-Search is (after resolving many issues, who expected that? ) up and running. You can search for any package there. Some issues are remaining, e.g. the file-contents-listing doesn t work, and changelog support is broken, but the basic functionality is there. Tanglu Bugtracker We now also have a bugtracker which is based on the Trac software. The Tanglu-Bugtracker is automatically synced with the Tanglu archive, meaning that you find all packages in Trac to report bugs against them. The dak will automatically update new packages every day. Trac still needs a few confort-adjustments, e.g. submitting replies via email or tracking package versions. Tanglu base system The Tanglu metapackages have been published in a first alpha version. We will support GNOME-3 and KDE4, as long as this is possible (= enough people working on the packaging). The Tanglu packages will also depend on systemd, which we will need in GNOME anyway, and which also allows some great new features in KDE. Side-effect of using systemd is at least for the start that Tanglu boots a bit slow, because we haven t done any systemd adjustments, and because systemd is very old. We will have to wait for the systemd and udev maintainers to merge the packages and release a new version first, before this will improve. (I don t want to do this downstream in Tanglu, because I don t know the plans for that at Debian (I only know the information Tollef Fog Heen & Co. provided at FOSDEM)) The community The community really surprised me! We got an incredible amount of great feedback on Tanglu, and most of the people liked the idea of Tanglu. I think we are one of the less-flamed new distributions ever started . Also, without the very active community, kickstarting Tanglu would not have been possible. My guess was that we might be able to have something running next year. Now, with the community help, I see a chance for a release in October The only thing people complained about was the name of the distribution. And to be really honest, I am not too happy with the name. But finding a name was an incredibe difficult process (finding something all parties liked), and Tanglu was a good compromise. Tanglu has absolutely no meaning, it was taken because it sounded interesting. The name was created by combining the Brazilian Tangerine (Clementine) and the German Iglu (igloo). I also dont think the name matters that much, and I am more interested in the system itself than the name of it. Also, companies produce a lot of incredibly weird names, Tanglu is relatively harmless compared to that . In general, thanks to everyone participating in Tanglu! You are driving the project forward! The first (planned) release I hereby announce the name of the first Tanglu release, 1.1 Aequorea Victoria . It is Daniel s fault that Tanglu releases will be named after jellyfishes, you can ask him why if you want I picked Aequorea, because this kind of jellyfish was particularly important for research in molecular biology. The GFP protein, a green fluorescent protein (=GFP), caused a small revolution in science and resulted in a Nobel Prize in 2008 for the researchers involved in GFP research (for the interested people: You can tag proteins with GFP and determine their position using light microscopy. GFP also made many other fancy new lab methods possible). Because Tanglu itself is more or less experimental at time, I found the connection to research just right for the very first release. We don t have a time yet when this version will be officially released, but I expect it to be in October, if the development speed increases a little and more developers get interested and work on it. Project Policy We will need to formalize the Tanglu project policy soon, both the technical and the social policies. In general, regarding free software and technical aspects, we strictly adhere to the Dbian Free Software Guidelines, the Debian Social Contract and the Debian Policy. Some extra stuff will be written later, please be patient! Tanglu OIN membership I was approached by the Open Invention Network, to join it as member. In general, I don t have objections to do that, because it will benefit Tanglu. However, the OIN has a very tolerant public stance on software patents, which I don t like that much. Debian did not join the OIN for this reason. For Tanglu, I think we could still join the OIN without someone thinking that we support the stance on software patents. Joining would simply be pragmatic: We support the OIN as a way to protect the Linux ecosystem from software patents, even if we don t like the stance on software patents and see it differently. Because this affects the whole Tanglu project, I don t want to decide this alone, but get some feedback from the Tanglu community before making a decision. Can I install Tanglu now? Yes and no. We don t provide installation images yet, so trying Tanglu is a difficult task (you need to install Debian and then upgrade it to Tanglu) if you want to experiment with it, I recomment trying Tanglu in a VM. I want to help! Great, then please catch one of us on IRC or subscribe to the mailinglists. The best thing is not to ask for work, but suggest something you want to do, others will then tell you if that is possible and maybe help with the task. Packages can for now only be uploaded by Debian Developers, Ubuntu Developers or Debian Maintainers who contacted me directly and whose keys have been verified. This will be changed later, but at the current state of the Tanglu archive (= less safety checks for packages), I only want people to upload stuff who definitely have the knowledge to create sane packages (you can also proove that otherwise, of course). We will later establish a new-member process. If you want to provide a Tanglu archive mirror, we would be very happy, so that the main server doesn t have to carry all the load. If you have experience in creating Linux Live-CDs or have worked with the Ubiquity installer, helping with these parts would be awesome! Unfortunately, we cannot reuse parts of Linux Mint Debian, because many of their packages don t build from source and are repackaged binaries, which is a no-go for the Tanglu main archive. Sneak peek And here is a screenshot of the very first Tanglu installation (currently more Debian than Tanglu):

Something else I am involved in Debian for a very long time now, first as Debian Maintainer and then as Debian Developer and I never thought much about the work the Debian system administrators do. I didn t know how dak worked or how Wanna-build handles the buildds and what exactly the ftpmasters have to do. By not knowing, I mean I knew the very basic theory and what these people do. But this is something different than experiencing how much work setting up and maintaining the infrastructure is and what an awesome job the people do for Debian, keeping it all up and running and secure! Kudos for that, to all people maintaining Debian infrastructure! You rock! (And I will never ever complain about slow buildds or packages which stay in NEW for too long )

Even though I haven't had much time to dedicate to http.debian.net lately, it has been up and running, or should I say serving?

Part of its job is to detect mirrors that have temporary issues or are entirely gone, down, unavailable. It does so, and many other things, by monitoring the so-called "trace files". A very important one being the "master" (or "origin") trace file.

With the recent integration of backports into the main archive, the master trace file of the backports mirrors also changed. Long story short, this change caused backports mirrors to no longer be considered by the mirror redirector as candidates. As long as they were up to date.

After the usual mirror synchronisation delay, more and more mirrors were disabled and subsets of "up to date" candidates re-calculated. This reached a critical point when only one mirror was left in the database. The mirror had not been synchronised for a couple of weeks.

This mirror is located in Costa Rica, and as the only candidate left in the database it was the only one used to serve requests for the backports archive. No matter where the client was located in the world.

The issue was later noticed and the necessary updates to the mirrors master list made. Mirrors started to be re-considered as they were re-checked (with some delay due to the rate limiter) and the subsets re-calculated. In a few hours everything was back to normality.

Correctness and fault-tolerance don't always get together very well...

The GNOME Foundation started the Free & Open Source Software Outreach Program for Women, OPW, in 2010. In the January-April 2013 round, many other FOSS organizations joined the program. We are happy to announce that Debian will also join in the next round from June-September and we'll offer one internship. You can find more details about Debian's participation in the program at Debian OPW page. Call for mentors and projects OPW allows applicants to work on any kind of project, including coding, design, marketing, web development... The Debian Google Summer of Code projects will be offered also as possible projects for OPW, but GSoC only allows coding projects. If you have any idea of a non-coding project and you want to mentor it, please contact us in the soc-coordination mailing list adding [OPW] in subject. OPW works in the same way as GSoC except Google doesn't play a part here. The same advice that is provided for GSoC mentors works for OPW mentors. Call for participants The main goal of this program is to increase the number of women in FOSS, so all women who are not yet a Debian Developer or a Debian Maintainer are encouraged to apply. There are no age restrictions and applicants don't need to be a student. If you want to apply, you must follow three steps:

1. Choose a project from this list. There are two lists, one for GSoC and another with non-coding tasks that can be only offered by the OPW. Those lists may change and add or remove more projects in the next few weeks.
2. Make a small contribution to Debian. Projects will add a task the applicant must complete as part of the pre-selection process. If no task is provided, you are welcome to ask the mentors of the project. You can also make a different extra task of the one listed to show your skills and interest.
3. Create a page in the Debian wiki with your application. You can do so under pseudonym, but in that case, please give us information about yourself privately by email to the coordinators listed in the Debian OPW page!

This is my monthly summary of my free software related activities. If you re among the people who made a donation to support my work (114.19 , thanks everybody!), then you can learn how I spent your money. Otherwise it s just an interesting status update on my various projects. Simple-CDD and debian-cd I tried to use wheezy s version of debian-cd and simple-cdd to generate an automatic installer. In this process, I filed a couple of bugs on simple-cdd (#701963: type-handling package is gone and should not be listed in default.downloads, and #701998: the --keyboard parameter is not working with wheezy s debian-installer) and I commited fixes for a few issues in debian-cd:

• r2518: adjust Makefile for new xorriso requirement
• r2520: add missing depends on dosfstools
• r2521: use --no-check-gpg when querying debootstrap
• r2522: make debian-cd work with a mirror without sources)

Debian France I completed the new website for Debian France and I put it online. Later I merged some supplementary enhancements prepared by Tanguy Ortolo (and I gave him commits rights at the same time). I tried to update our Galette installation to the latest upstream version but I reverted to the former version after having encountered two problems (filed here and here). In the process, I created a Debian package for galette (you can grab it on git.debian.org). I also suggested an idea of improvement for Galette s paypal plugin and it has been quickly implemented. Thus I updated the plugin installed on france.debian.net. Kali related work It s been a few months that I have been helping the Kali team to prepare this new Debian derivative. Now that the derivative has gone public, I can attribute some of my Debian work to my collaboration with the Kali team. This month I contributed a few features and fixes to debian-installer and live-build:

• #702257: new preseed entry to disable CDROM entries
• #703072: hid-generic module is missing from input-modules udeb (affecting experimental kernel only)
• Fix win32-loader support in live-build

After the launch, we registered Kali in the derivative census. Paul Wise quickly reported some misfiled bugs from early Kali users and I discovered that reportbug was not behaving properly even though we correctly updated base-files (see #703678 on reportbug and #703677 on lsb-release). Misc packaging work

• I sponsored a new upstream version of dnsjava because it s required by Jitsi.
• I prepared rebuild 0.4.1.1 and uploaded it to testing-proposed-updates for a RC bug fix.
• I uploaded Publican 3.1.5 to experimental and filed #703514 to request a new upstream version of docbook-xsl that is needed by Publican.
• I filed #703995 to fix apt-setup s handling of the apt-setup/multiarch preseed option.

DPL election I also spent quite some time to read and participate to the discussions on debian-vote since it was campaigning time for the DPL candidates Thanks This was a rather active month if you take into account the fact that I got a second son Lucas on March 6th. See you next month for a new summary of my activities.

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