Search Results: "spa"

20 March 2017

Shirish Agarwal: Tale of two countries, India and Canada

Apologies the first blog post got sent out by mistake. Weather comparisons between the two countries Last year, I had come to know that this year s debconf is happening in Canada, a cold country. Hence, few weeks/month back, I started trying to find information online when I stumbled across few discussion boards where people were discussing about Innerwear and Outerwear and I couldn t understand what that was all about. Then somehow stumbled across this Video, which is of a game called the Long Dark and just seeing couple of episodes it became pretty clear to me why the people there were obsessing with getting the right clothes and everything about it. Couple of Debconf people were talking about the weather in Montreal, and surprise, surprise it was snowing there, in fact supposed to be near the storm of the century. Was amazed to see that they have a website to track how much snow has been lifted. If we compare that to Pune, India weather-wise we are polar opposites. There used to be a time, when I was very young, maybe 5 yrs. old that once the weather went above 30 degree celsius, rains would fall, but now its gonna touch 40 degrees soon. And April and May, the two hottest months are yet to come. China Gate Before I venture further, I was gifted the book China Gate written by an author named William Arnold. When I read the cover and the back cover, it seemed the story was set between China and Taiwan, later when I started reading it, it shares history of Taiwan going back 200 or so odd years. This became relevant as next year s Debconf, Debconf 2018 will be in Taiwan, yes in Asia very much near to India. I am ashamed to say that except for the Tiananmen Square Massacre and the Chinese High-Speed Rail there wasn t much that I knew. According to the book, and I m paraphrasing here the gist I got was that for a long time, the Americans promised Taiwan it will be an Independent country forever, but due to budgetary and other political constraints, the United States took the same stand as China from 1979. Interestingly, now it seems Mr. Trump wants to again recognize Taiwan as a separate entity from China itself but as is with Mr. Trump you can t be sure of why he does, what he does. Is it just a manoeuvrer designed to out-smart the chinese and have a trade war or something else, only time will tell. One thing which hasn t been shared in the book but came to know via web is that Taiwan calls itself Republic of China . If Taiwan wants to be independent then why the name Republic of China ? Doesn t that strengthen China s claim that Taiwan is an integral part of China. I don t understand it. The book does seduce you into thinking that the events are happening in real-time, as in happening now. That s enough OT for now. null Population Density As well in the game and whatever I could find on the web, Canada seems to be on the lower side as far as population is concerned. IIRC, few years back, Canadians invited Indian farmers and gave them large land-holdings for over 100 years on some small pittance. While the link I have shared is from 2006, I read it online and in newspapers even as late as in 2013/2014. The point being there seems to be lot of open spaces in Canada, whereas in India we fight for even one inch literally, due to overpopulation. This sharing reminded me of Mark of Gideon . While I was young, I didn t understand the political meaning of it and still struggle to understand about whom the show was talking about. Was it India, Africa or some other continent they were talking about ? This also becomes obvious when you figure out the surface area of the two countries. When I had started to learn about Canada, I had no idea, nor a clue that Canada is three times the size of India. And this is when I know India is a large country. but seeing that Canada is thrice larger just boggled my mind. As a typical urbanite, would probably become mad if in a rural area in Canada. Montreal, however seems to be something like Gwalior or Bangalore before IT stormed in, seems to be a place where people can work, play and have quite a few gardens as well. Rail This is one thing that is similar in both the great countries. India has Indian Railways and while the Canadians have their own mountain railway called viarail. India chugs on its 68k kilometre network, Canada is at fourth position with 52k network. With thrice the land size, it should have been somewhere where Russia is or even better than them. It would be interesting if a Canadian/s comment about their railway network and why it is so bad in terms of reach. As far as food is concerned, somebody shared this Also, have no idea if Canadian trains are as entertaining as Indian ones, in terms of diverse group of people as well as variety of food to eat as also shared a bit in the video. I am not aware whether Via Rail is the only network operator and there are other network operators unlike Indian Railways which has monopoly on most of the operations. Countries which have first past the post system - Wikipedia Business houses, Political Families This is again something that is similar in both the countries, it seems (from afar) that its only few business houses and more importantly political families which have governed for years. From what little I could understand, both India and Canada have first past the post system which as shared by its critics is unfair to new and small parties. It would be interesting to see if Canada does a re-think. For India, it would need a massive public education outreach policy and implementation. We just had elections in 5 states of India with U.P. (with respect to area-size and population density) and from the last several years, the EVM s (Electronic Voting Machines) tries to make sure that nobody could know which area which party got the most votes. This is to make sure the winning party is not able to take revenge on people or areas which did not vote for them. Instead you have general region counting of votes with probably even the Election Commission not knowing which EVM went to what area and what results are there in sort of double-blind methodology. As far as Business houses are concerned, I am guessing it s the same world-over, only certain people hold the wealth while majority of us are in hard-working, non-wealthy status. Northern Lights - Aurora Borealis Northern Lights, Aurora Borealis Apart from all the social activities that Montreal is famous for, somebody told/shared with me that it is possible to see the Northern Lights, Aurora Borealis can be seen in Canada. I dunno how true or not it is, while probably in Montreal it isn t possible to see due to light pollution, but maybe around 40-50 kms. from the city ? Can people see it from Canada ? IF yes, how far would you have to go ? Are there any companies or people who take people to see the Northern Lights. While I still have to apply for bursary, and if that gets ok, then try getting the visa, but if that goes through, apart from debconf and social activities happening in and around Montreal, Museums, Music etc. , this would be something I would like to experience if it s possible. While I certainly would have to be prepared for the cold that would be, if it s possible, no offence to debconf or anybody else but it probably would be the highlight of the entire trip if its possible. This should be called/labelled as the greatest show on earth TM.
Filed under: Miscellenous Tagged: # Population Density, #Area size, #Aurora Borealis, #Canada, #Trains, DebConf, India, politics

Shirish Agarwal: Canada and India, similarities and differences.

Weather comparisons between the two countries Few days/weeks back, I had come to know that Canada, where this year s debconf is happening is cold country. I started trying to find information online when I stumbled across few boards where people were discussing about innerwear and outerwear and I couldn t understand what that was all about. Then somehow stumbled across this game, it s called the Long Dark and just seeing couple of episodes it became pretty clear to me why the people there were obsessing with getting the right clothes and everything about it. Couple of Debconf people were talking about weather in Montreal, and surprise, surprise it was snowing there, in fact supposed to be near the storm of the century. Was amazed to see that they have a website to track how much snow has been lifted. If we compare that to Pune, India weather-wise we are polar opposites. There used to be a time, when I was very young, maybe 5 yrs. old that once the weather went above 30 degree celcius, rains would fall, but now its gonna touch 40 degrees soon. And April and May, the two hottest months are yet to come. China Gate Before I venture further, I was gifted the book China Gate written by an author named William Arnold. When I read the cover and the backcover, it seemed the story was set between China and Taiwan, later when I started reading it, it shares history of Taiwan going back 200 or so odd years. This became relevant as next year s Debconf, Debconf 2018 will be in Taiwan, yes in Asia very much near to India. I am ashamed to say that except for the Tiananmen Square Massacre and the Chinese High-Speed Rail there wasn t much that I knew. According to the book, and I m paraphrasing here the gist I got was that for a long time, the Americans promised Taiwan it will be an Independent country forever, but due to budgetary and other political constraints, the United States took the same stand as China from 1979 and now it seems Mr. Trump wants to again recognize Taiwan as a separate entity from China itself. One thing which hasn t been shared in the book but came to know via web is that Taiwan calls itself Republic of China . If Taiwan wants to be independent then why the name Republic of China ? Doesn t that strengthen China s claim that Taiwan is an integral part of China. I don t understand it. The book does seduce you into thinking that the events are happening in real-time, as in happening now. That s enough OT for now. null Population Density As well in the game and whatever I could find on the web, Canada seems to be on the lower side as far as population is concerned. IIRC, few years back, Canadians invited Indian farmers and gave them large land-holdings for over 100 years on some small pittance. While the link I have shared is from 2006, I read it online and in newspapers even as late as in 2013/2014. The point being there seems to be lot of open spaces in Canada, whereas in India we fight for even one inch literally, due to overpopulation. This sharing reminded me of Mark of Gideon . While I was young, I didn t understand the political meaning of it and still struggle to understand about whom the show was talking about. Was it India, Africa or some other continent they were talking about ? This also becomes obvious when you figure out the surface area of the two countries. When I had started to learn about Canada, I had no idea, nor a clue that Canada is three times the size of India. And this is when I know India is a large country. but seeing that Canada is thrice larger just boggled my mind. As a typical urbanite, would probably become mad if in a rural area in Canada. Montreal, however seems to be something like Gwalior or Bangalore before IT stormed in, seems to be a place where people can work, play and have quite a few gardens as well. Rail This is one thing that is similar in both the great countries. India has Indian Railways and while the Canadians have their own mountain railway called viarail. India chugs on its 68k kilometre network, Canada is at fourth position with 52k network. With thrice the land size, it should have been somewhere where Russia is or even better than them. It would be interesting if Canadians comment about their railway network and why it is so bad in terms of reach. Business houses, Political Families This is again something that is similar in both the countries, it seems (from afar) that its only few business houses and more importantly political families which have governed for years.
Filed under: Miscellenous

18 March 2017

Vincent Sanders: A rose by any other name would smell as sweet

Often I end up dealing with code that works but might not be of the highest quality. While quality is subjective I like to use the idea of "code smell" to convey what I mean, these are a list of indicators that, in total, help to identify code that might benefit from some improvement.

Such smells may include:
I am most certainly not alone in using this approach and Fowler et al have covered this subject in the literature much better than I can here. One point I will raise though is some programmers dismiss code that exhibits these traits as "legacy" and immediately suggest a fresh implementation. There are varying opinions on when a rewrite is the appropriate solution from never to always but in my experience making the old working code smell nice is almost always less effort and risk than a re-write.
TestsWhen I come across smelly code, and I decide it is worthwhile improving it, I often discover the biggest smell is lack of test coverage. Now do remember this is just one code smell and on its own might not be indicative, my experience is smelly code seldom has effective test coverage while fresh code often does.

Test coverage is generally understood to be the percentage of source code lines and decision paths used when instrumented code is exercised by a set of tests. Like many metrics developer tools produce, "coverage percentage" is often misused by managers as a proxy for code quality. Both Fowler and Marick have written about this but sufficient to say that for a developer test coverage is a useful tool but should not be misapplied.

Although refactoring without tests is possible the chances for unintended consequences are proportionally higher. I often approach such a refactor by enumerating all the callers and constructing a description of the used interface beforehand and check that that interface is not broken by the refactor. At which point is is probably worth writing a unit test to automate the checks.

Because of this I have changed my approach to such refactoring to start by ensuring there is at least basic API code coverage. This may not yield the fashionable 85% coverage target but is useful and may be extended later if desired.

It is widely known and equally widely ignored that for maximum effectiveness unit tests must be run frequently and developers take action to rectify failures promptly. A test that is not being run or acted upon is a waste of resources both to implement and maintain which might be better spent elsewhere.

For projects I contribute to frequently I try to ensure that the CI system is running the coverage target, and hence the unit tests, which automatically ensures any test breaking changes will be highlighted promptly. I believe the slight extra overhead of executing the instrumented tests is repaid by having the coverage metrics available to the developers to aid in spotting areas with inadequate tests.
ExampleA short example will help illustrate my point. When a web browser receives an object over HTTP the server can supply a MIME type in a content-type header that helps the browser interpret the resource. However this meta-data is often problematic (sorry that should read "a misleading lie") so the actual content must be examined to get a better answer for the user. This is known as mime sniffing and of course there is a living specification.

The source code that provides this API (Linked to it rather than included for brevity) has a few smells:
While some of these are obvious the non-use of the global string table and the API complexity needed detailed knowledge of the codebase, just to highlight how subjective the sniff test can be. There is also one huge air freshener in all of this which definitely comes from experience and that is the modules author. Their name at the top of this would ordinarily be cause for me to move on, but I needed an example!

First thing to check is the API use

$ git grep -i -e mimesniff_compute_effective_type --or -e mimesniff_init --or -e mimesniff_fini
content/hlcache.c:              error = mimesniff_compute_effective_type(handle, NULL, 0,
content/hlcache.c:              error = mimesniff_compute_effective_type(handle,
content/hlcache.c:              error = mimesniff_compute_effective_type(handle,
content/mimesniff.c:nserror mimesniff_init(void)
content/mimesniff.c:void mimesniff_fini(void)
content/mimesniff.c:nserror mimesniff_compute_effective_type(llcache_handle *handle,
content/mimesniff.h:nserror mimesniff_compute_effective_type(struct llcache_handle *handle,
content/mimesniff.h:nserror mimesniff_init(void);
content/mimesniff.h:void mimesniff_fini(void);
desktop/netsurf.c:      ret = mimesniff_init();
desktop/netsurf.c:      mimesniff_fini();

This immediately shows me that this API is used in only a very small area, this is often not the case but the general approach still applies.

After a little investigation the usage is effectively that the mimesniff_init API must be called before the mimesniff_compute_effective_type API and the mimesniff_fini releases the initialised resources.

A simple test case was added to cover the API, this exercised the behaviour both when the init was called before the computation and not. Also some simple tests for a limited number of well behaved inputs.

By changing to using the global string table the initialisation and finalisation API can be removed altogether along with a large amount of global context and pre-processor macros. This single change removes a lot of smell from the module and raises test coverage both because the global string table already has good coverage and because there are now many fewer lines and conditionals to check in the mimesniff module.

I stopped the refactor at this point but were this more than an example I probably would have:
ConclusionThe approach examined here reduce the smell of code in an incremental, testable way to improve the codebase going forward. This is mainly necessary on larger complex codebases where technical debt and bit-rot are real issues that can quickly overwhelm a codebase if not kept in check.

This technique is subjective but helps a programmer to quantify and examine a piece of code in a structured fashion. However it is only a tool and should not be over applied nor used as a metric to proxy for code quality.

17 March 2017

Antonio Terceiro: Patterns for Testing Debian Packages

At the and of 2016 I had the pleasure to attend the 11th Latin American Conference on Pattern Languages of Programs, a.k.a SugarLoaf PLoP. PLoP is a series of conferences on Patterns (as in Design Patterns ), a subject that I appreciate a lot. Each of the PLoP conferences but the original main big conference has a funny name. SugarLoaf PLoP is called that way because its very first edition was held in Rio de Janeiro, so the organizers named it after a very famous mountain in Rio. The name stuck even though a long time has passed since it was held in Rio for the last time. 2016 was actually the first time SugarLoaf PLoP was held outside of Brazil, finally justifying the Latin American part of its name. I was presenting a paper I wrote on patterns for testing Debian packages. The Debian project funded my travel expenses through the generous donations of its supporters. PLoP s are very fun conferences with a relaxed atmosphere, and is amazing how many smart (and interesting!) people gather together for them. My paper is titled Patterns for Writing As-Installed Tests for Debian Packages , and has the following abstract:
Large software ecosystems, such as GNU/Linux distributions, demand a large amount of effort to make sure all of its components work correctly invidually, and also integrate correctly with each other to form a coherent system. Automated Quality Assurance techniques can prevent issues from reaching end users. This paper presents a pattern language originated in the Debian project for automated software testing in production-like environments. Such environments are closer in similarity to the environment where software will be actually deployed and used, as opposed to the development environment under which developers and regular Continuous Integration mechanisms usually test software products. The pattern language covers the handling of issues arising from the difference between development and production-like environments, as well as solutions for writing new, exclusive tests for as-installed functional tests. Even though the patterns are documented here in the context of the Debian project, they can also be generalized to other contexts.
In practical terms, the paper documents a set of patterns I have noticed in the last few years, when I have been pushing the Debian Continous Integration project. It should be an interesting read for people interested in the testing of Debian packages in their installed form, as done with autopkgtest. It should also be useful for people from other distributions interested in the subject, as the issues are not really Debian-specific. I have recently finished the final version of the paper, which should be published in the ACM Digital Library at any point now. You can download a copy of the paper in PDF. Source is also available, if you are into markdown, LaTeX, makefiles and this sort of thing. If everything goes according to plan, I should be presenting a talk on this at the next Debconf in Montreal.

16 March 2017

Joey Hess: end of an era

I'm at home downloading hundreds of megabytes of stuff. This is the first time I've been in position of "at home" + "reasonably fast internet" since I moved here in 2012. It's weird! Satellite internet dish with solar panels in foreground While I was renting here, I didn't mind dialup much. In a way it helps to focus the mind and build interesting stuff. But since I bought the house, the prospect of only dialup at home ongoing became more painful. While I hope to get on the fiber line that's only a few miles away eventually, I have not convinced that ISP to build out to me yet. Not enough neighbors. So, satellite internet for now. 9.1 dB SNR speedtest results: 15 megabit down / 4.5 up with significant variation Dish seems well aligned, speed varies a lot, but is easily hundreds of times faster than dialup. Latency is 2x dialup. The equipment uses more power than my laptop, so with the current solar panels, I anticipate using it only 6-9 months of the year. So I may be back to dialup most days come winter, until I get around to adding more PV capacity. It seems very cool that my house can capture sunlight and use it to beam signals 20 thousand miles into space. Who knows, perhaps there will even be running water one day. Satellite dish

Raphaël Hertzog: Freexian s report about Debian Long Term Support, February 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In January, about 154 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly thanks to Bearstech and LiHAS joining us. The security tracker currently lists 45 packages with a known CVE and the dla-needed.txt file 39. The number of open issues continued its slight increase, this time it could be explained by the fact that many contributors did not spend all the hours allocated (for various reasons). There s nothing worrisome at this point. Thanks to our sponsors New sponsors are in bold.

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Enrico Zini: Django signing signs, does not encrypt

As is says in the documentation. django.core.signing signs, and does not encyrpt. Even though signing.dumps creates obscure-looking tokens, they are not encrypted, and here's a proof: 
>>> from django.core import signing
>>> a = signing.dumps( "action":"set-password", "username": "enrico", "password": "SECRET" )
>>> from django.utils.encoding import force_bytes
>>> print(signing.b64_decode(force_bytes(a.split(":",1)[0])))
b' "action":"set-password","password":"SECRET","username":"enrico" '
I'm writing it down so one day I won't be tempted to think otherwise.

15 March 2017

Dirk Eddelbuettel: RcppEigen 0.3.2.9.1

A new maintenance release 0.3.2.9.1 of RcppEigen, still based on Eigen 3.2.9 is now on CRAN and is now going into Debian soon. This update ensures that RcppEigen and the Matrix package agree on their #define statements for the CholMod / SuiteSparse library. Thanks to Martin Maechler for the pull request. I also added a file src/init.c as now suggested (soon: requested) by the R CMD check package validation. The complete NEWS file entry follows.

Changes in RcppEigen version 0.3.2.9.1 (2017-03-14)
  • Synchronize CholMod header file with Matrix package to ensure binary compatibility on all platforms (Martin Maechler in #42)
  • Added file init.c with calls to R_registerRoutines() and R_useDynamicSymbols(); also use .registration=TRUE in useDynLib in NAMESPACE

Courtesy of CRANberries, there is also a diffstat report for the most recent release.

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

14 March 2017

Keith Packard: Valve

Consulting for Valve in my spare time Valve Software has asked me to help work on a couple of Linux graphics issues, so I'll be doing a bit of consulting for them in my spare time. It should be an interesting diversion from my day job working for Hewlett Packard Enterprise on Memory Driven Computing and other fun things. First thing on my plate is helping support head-mounted displays better by getting the window system out of the way. I spent some time talking with Dave Airlie and Eric Anholt about how this might work and have started on the kernel side of that. A brief synopsis is that we'll split off some of the output resources from the window system and hand them to the HMD compositor to perform mode setting and page flips. After that, I'll be working out how to improve frame timing reporting back to games from a composited desktop under X. Right now, a game running on X with a compositing manager can't tell when each frame was shown, nor accurately predict when a new frame will be shown. This makes smooth animation rather difficult.

Reproducible builds folks: Reproducible Builds: week 98 in Stretch cycle

Here's what happened in the Reproducible Builds effort between Sunday March 5 and Saturday March 11 2017: Upcoming events Reproducible Builds Hackathon Hamburg The Reproducible Builds Hamburg Hackathon 2017, or RB-HH-2017 for short, is a 3 day hacking event taking place in the CCC Hamburg Hackerspace located inside the Frappant, which is collective art space located in a historical monument in Hamburg, Germany. The aim of the hackathon is to spent some days working on Reproducible Builds in every distribution and project. The event is open to anybody interested on working on Reproducible Builds issues in any distro or project, with or without prio experience! Packages filed Chris Lamb: Toolchain development Reviews of unreproducible packages 39 package reviews have been added, 7 have been updated and 9 have been removed in this week, adding to our knowledge about identified issues. 2 issue types have been added: Weekly QA work During our reproducibility testing, FTBFS bugs have been detected and reported by: buildinfo.debian.net development reproducible-website development tests.reproducible-builds.org Misc. This week's edition was written by Chris Lamb, Holger Levsen, Vagrant Cascadian & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

12 March 2017

Iustin Pop: A recipe for success

It is said that with age comes wisdom. I would be happy for that to be true, because today I must have been very very young then. For example, if you want to make a long bike ride in order to hit some milestone, like your first metric century, it is not indicated to follow ANY of the following points: For bonus points, if you somehow manage to reach the third peak in the above ride, and have mostly only flat/down to the destination, do the following: be so glad you're done with climbing, that you don't pay attention to the map and start a wrong descent, on a busy narrow road, so that you can't stop immediately as you realise you've lost the track; it will cost you only an extra ~80 meters of height towards the end of the ride. Which are pretty cheap, since all the food is gone and the water almost as well, so the backpack is light. Right. However, if you do follow all the above, you're rewarded with a most wonderful thing for the second half of the ride: your will receive a +5 boost on your concentration skill. You will be able to focus on, and think about a single thing for hours at a time, examining it (well, its contents) in minute detail. Plus, when you get home and open that thing I mean, of course, the FRIDGE with all the wonderful FOOD it contains everything will taste MAGICAL! You can now recoup the roughly 1500 calories deficit on the ride, and finally no longer feel SO HUNGRY. That's all. Strava said "EXTREME" suffer score, albeit less than 20% points in the red, which means I was just slugging through the ride (total time confirms it), like a very very very old man. But definitely not a wise one.

Mike Hommey: When the memory allocator works against you

Cloning mozilla-central with git-cinnabar requires a lot of memory. Actually too much memory to fit in a 32-bits address space. I hadn t optimized for memory use in the first place. For instance, git-cinnabar keeps sha-1s in memory as hex values (40 bytes) rather than raw values (20 bytes). When I wrote the initial prototype, it didn t matter that much, and while close(ish) to the tipping point, it didn t require more than 2GB of memory at the time. Time passed, and mozilla-central grew. I suspect the recent addition of several thousands of commits and files has made things worse. In order to come up with a plan to make things better (short or longer term), I needed data. So I added some basic memory resource tracking, and collected data while cloning mozilla-central. I must admit, I was not ready for what I witnessed. Follow me for a tale of frustrations (plural). I was expecting things to have gotten worse on the master branch (which I used for the data collection) because I am in the middle of some refactoring and did many changes that I was suspecting might have affected memory usage. I wasn t, however, expecting to see the clone command using 10GB(!) memory at peak usage across all processes. (Note, those memory sizes are RSS, minus shared ) It also was taking an unexpected long time, but then, I hadn t cloned a large repository like mozilla-central from scratch in a while, so I wasn t sure if it was just related to its recent growth in size or otherwise. So I collected data on 0.4.0 as well. Less time spent, less memory usage ok. There s definitely something wrong on master. But wait a minute, that slope from ~2GB to ~4GB on the git-remote-hg process doesn t actually make any kind of sense. I mean, I d understand it if it were starting and finishing with the Import manifest phase, but it starts in the middle of it, and ends long before it finishes. WTH? First things first, since RSS can be a variety of things, I checked /proc/$pid/smaps and confirmed that most of it was, indeed, the heap. That s the point where you reach for Google, type something like python memory profile and find various tools. One from the results that I remembered having used in the past is guppy s heapy. Armed with pdb, I broke execution in the middle of the slope, and tried to get memory stats with heapy. SIGSEGV. Ouch. Let s try something else. I reached out to objgraph and pympler. SIGSEGV. Ouch again. Tried working around the crashes for a while (too long while, retrospectively, hindsight is 20/20), and was somehow successful at avoiding them by peaking at a smaller set of objects. But whatever I did, despite being attached to a process that had 2.6GB RSS, I wasn t able to find more than 1.3GB of data. This wasn t adding up. It surely didn t help that getting to that point took close to an hour each time. Retrospectively, I wish I had investigated using something like Checkpoint/Restore in Userspace. Anyways, after a while, I decided that I really wanted to try to see the whole picture, not smaller peaks here and there that might be missing something. So I resolved myself to look at the SIGSEGV I was getting when using pympler, collecting a core dump when it happened. Guess what? The Debian python-dbg package does not contain the debug symbols for the python package. The core dump was useless. Since I was expecting I d have to fix something in python, I just downloaded its source and built it. Ran the command again, waited, and finally got a backtrace. First Google hit for the crashing function? The exact (unfixed) crash reported on the python bug tracker. No patch. Crashing code is doing: 
((f)->f_builtins != (f)->f_tstate->interp->builtins)
And (f)->f_tstate is NULL. Classic NULL deref. Added a guard (assessing it wouldn t break anything). Ran the command again. Waited. Again. SIGSEGV. Facedesk. Another crash on the same line. Did I really use the patched python? Yes. But this time (f)->f_tstate->interp is NULL. Sigh. Same player, shoot again. Finally, no crash but still stuck on only 1.3GB accounted for. Ok, I know not all python memory profiling tools are entirely reliable, let s try heapy again. SIGSEGV. Sigh. No debug info on the heapy module, where the crash happens. Sigh. Rebuild the module with debug info, try again. The backtrace looks like heapy is recursing a lot. Look at %rsp, compare with the address space from /proc/$pid/maps. Confirmed. A stack overflow. Let s do ugly things and increase the stack size in brutal ways. Woohoo! Now heapy tells me there s even less memory used than the 1.3GB I found so far. Like, half less. Yeah, right. I m not clear on how I got there, but that s when I found gdb-heap, a tool from Red Hat s David Malcolm, and the associated talk Dude, where s my RAM? A deep dive into how Python uses memory (slides). With a gdb attached, I would finally be able to rip python s guts out and find where all the memory went. Or so I thought. The gdb-heap tool only found about 600MB. About as much as heapy did, for that matter, but it could be coincidental. Oh. Kay. I don t remember exactly what went through my mind then, but, since I was attached to a running process with gdb, I typed the following on the gdb prompt: 
gdb> call malloc_stats()
And that s when the truth was finally unvealed: the memory allocator was just acting up the whole time. The ouput was something like: 
Arena 0:
system bytes    =  some number above (but close to) 2GB
in use bytes    =  some number above (but close to) 600MB
Yes, the glibc allocator was just telling it had allocated 600MB of memory, but was holding onto 2GB. I must have found a really bad allocation pattern that causes massive fragmentation. One thing that David Malcolm s talk taught me, though, is that python uses its own allocator for small sizes, so the glibc allocator doesn t know about them. And, roughly, adding the difference between RSS and what glibc said it was holding to to the use bytes it reported somehow matches the 1.3GB I had found so far. So it was time to see how those things evolved in time, during the entire clone process. I grabbed some new data, tracking the evolution of system bytes and in use bytes . There are two things of note on this data: In fact, the latter is exactly how git-cinnabar is supposed to work: It reads changesets and manifests chunks, and holds onto them while importing files. Then it throws away those manifests and changesets chunks one by one while it imports them. There is, however, some extra bookkeeping that requires some additional memory, but it s expected to be less memory consuming than keeping all the changesets and manifests chunks in memory. At this point, I thought a possible explanation is that since both python and glibc are mmap()ing their own arenas, they might be intertwined in a way that makes things not go well with the allocation pattern happening during the Import manifest phase (which, in fact, allocates and frees increasingly large buffers for each manifest, as manifests grow in size in the mozilla-central history). To put the theory at work, I patched the python interpreter again, making it use malloc() instead of mmap() for its arenas. Aha! I thought. That definitely looks much better. Less gap between what glibc says it requested from the system and the RSS size. And, more importantly, no runaway increase of memory usage in the middle of nowhere. I was preparing myself to write a post about how mixing allocators could have unintended consequences. As a comparison point, I went ahead and ran another test, with the python allocator entirely disabled, this time. Heh. It turns out glibc was acting up all alone. So much for my (plausible) theory. (I still think mixing allocators can have unintended consequences.) (Note, however, that the reason why the python allocator exists is valid: without it, the overall clone took almost 10 more minutes) And since I had been getting all this data with 0.4.0, I gathered new data without the python allocator with the master branch. This paints a rather different picture than the original data on that branch, with much less memory use regression than one would think. In fact, there isn t much difference, except for the spike at the end, which got worse, and some of the noise during the Import manifests phase that got bigger, implying larger amounts of temporary memory used. The latter may contribute to the allocation patterns that throw glibc s memory allocator off. It turns out tracking memory usage in python 2.7 is rather painful, and not all the tools paint a complete picture of it. I hear python 3.x is somewhat better in that regard, and I hope it s true, but at the moment, I m stuck with 2.7. The most reliable tool I ve used here, it turns out, is pympler. Or rebuilding the python interpreter without its allocator, and asking the system allocator what is allocated. With all this data, I now have some defined problems to tackle, some easy (the spike at the end of the clone), and some less easy (working around glibc allocator s behavior). I have a few hunches as to what kind of allocations are causing the runaway increase of RSS. Coincidentally, I m half-way through a refactor of the code dealing with manifests, and it should help dealing with the issue. But that will be the subject of a subsequent post.

Steve Kemp: How I started programming

I've written parts of this story in the past, but never in one place and never in much detail. So why not now? In 1982 my family moved house, so one morning I went to school and at lunch-time I had to walk home to a completely different house. We moved sometime towards the end of the year, and ended up spending lots of money replacing the windows of the new place. For people in York I was born in Farrar Street, Y010 3BY, and we moved to a place on Thief Lane, YO1 3HS. Being named as it was I "ironically" stole at least two street-signs and hung them on my bedroom wall. I suspect my parents were disappointed. Anyway the net result of this relocation, and the extra repairs meant that my sisters and I had a joint Christmas present that year, a ZX Spectrum 48k. I tried to find pictures of what we received but unfortunately the web doesn't remember the precise bundle. All together though we received: I know we also received Horace and the Spiders, and I have vague memories of some other things being included, including a Space Invaders clone. No doubt my parents bought them separately. Highlights of my Spectrum-gaming memories include R-Type, Strider, and the various "Dizzy" games. Some of the latter I remember very fondly. Unfortunately this Christmas was pretty underwhelming. We unpacked the machine, we cabled it up to the family TV-set - we only had the one, after all - and then proceeded to be very disappointed when nothing we did resulted in a successful game! It turns out our cassette-deck was not good enough. Being back in the 80s the shops were closed over Christmas, and my memory is that it was around January before we received a working tape-player/recorder, such that we could load games. Happily the computer came with manuals. I read one, skipping words and terms I didn't understand. I then read the other, which was the spiral-bound orange book. It contained enough examples and decent wording that I learned to write code in BASIC. Not bad for an 11/12 year old. Later I discovered that my local library contained "computer books". These were colourful books that promised "The Mystery of Silver Mounter", or "Write your own ADVENTURE PROGRAMS". But were largely dry books that contained nothing but multi-page listings of BASIC programs to type in. Often with adjustments that had to be made for your own computer-flavour (BASIC varying between different systems).
If you want to recapture the magic scroll to the foot of this Osbourne page and you can download them!
Later I taught myself Z80 Assembly Language, partly via the Spectrum manual and partly via such books as these two (which I still own 30ish years later): Pretty much the only reason I continued down this path is because I wanted infinite/extra lives in the few games I owned. (Which were largely pirated via the schoolboy network of parents with cassette-copiers.) Eventually I got some of my l33t POKES printed in magazines, and received free badges from the magazines of the day such as Your Sinclair & Sinclair User. For example I was "Hacker of the Month" in the Your Sinclair issue 67 , Page 32, apparently because I "asked so nicely in my letter". Terrible scan is terrible: Anyway that takes me from 1980ish to 1984. The only computer I ever touched was a Spectrum. Friends had other things, and there were Sega consoles, but I have no memories of them. Suffice it to say that later when I first saw a PC (complete with Hercules graphics, hard drives, and similar sourcery, running GEM IIRC) I was pleased that Intel assembly was "similar" to Z80 assembly - and now I know the reason why. Some time in the future I might document how I got my first computer job. It is hillarious. As was my naivete.

10 March 2017

Mart n Ferrari: SunCamp happening again this May!

As I announced in mailing lists a few days ago, the Debian SunCamp (DSC2017) is happening again this May. SunCamp different to most other Debian events. Instead of a busy schedule of talks, SunCamp focuses on the hacking and socialising aspect, without making it just a Debian party/vacation.
DSC2016 - Hacking and discussing
The idea is to have 4 very productive days, staying in a relaxing and comfy environment, working on your own projects, meeting with your team, or presenting to fellow Debianites your most recent pet project.
DSC2016 - Tincho talking about Prometheus
We have tried to make this event the simplest event possible, both for organisers and attendees. There will be no schedule, except for the meal times at the hotel. But these can be ignored too, there is a lovely bar that serves snacks all day long, and plenty of restaurants and caf s around the village. DSC2016 - Hacking and discussing The SunCamp is an event to get work done, but there will be time for relaxing and socialising too.
DSC2016 - Well deserved siesta
DSC2016 - Playing P tanque
Do you fancy a hack-camp in a place like this? Swimming pool Caf Caf terrace One of the things that makes the event simple, is that we have negotiated a flat price for accommodation that includes usage of all the facilities in the hotel, and optionally food. We will give you a booking code, and then you arrange your accommodation as you please, you can even stay longer if you feel like it! The rooms are simple but pretty, and everything has been renovated very recently. Room Room view We are not preparing a talks programme, but we will provide the space and resources for talks if you feel inclined to prepare one. You will have a huge meeting room, divided in 4 areas to reduce noise, where you can hack, have team discussions, or present talks. Hacklab Hacklab Do you want to see more pictures? Check the full gallery
Debian SunCamp 2017 Hotel Anabel, LLoret de Mar, Province of Girona, Catalonia, Spain May 18-21, 2017
Tempted already? Head to the wikipage and register now, it is only 2 months away! Please try to reserve your room before the end of March. The hotel has reserved a number of rooms for us until that time. You can reserve a room after March, but we can't guarantee the hotel will still have free rooms. Comment

7 March 2017

Daniel Stender: Remotely deploy a WSGI application (as a Debian package) with Ansible

This is a mini workshop as an introduction into using Ansible for the administration of Debian systems. As an example it s shown how this configuration management tool can be used to remotely set up a simple WSGI application running on an Apache web server on a Debian installation to make it available on the net. The application which is used as an example is httpbin by Runscope. This is an useful HTTP request service for the development of web software or any other purposes which features a number of specific endpoints that can be used for different testing matters. For example, the address http://<address>/user-agent of httpbin returns the user agent identification of the client program which has been used to query it (that s taken from the header of the request). There are official instances of this request server running on the net, like the one at http://httpbin.org/. WSGI is a widespread standard for programming web application in Python, and httpbin is implemented in Python using the Flask web framework. The basis of the workshop is a simple base installation of an up-to-date Debian 8 Jessie on a demonstration host, and the latest official release of that is 8.7. As a first step, the installation has to be switched over to the testing branch of Debian, because the Debian packages of httpbin are comparatively new and are going to be introduced into the stable branch of the archive the first time with the upcoming major release number 9 Stretch . After that, the Apache packages which are needed to make it available (apache2 and libapache2-mod-wsgi other web servers of course could be used instead), and which are not part of a base installation, are installed from the archive. The web server then gets launched remotely, and the httpbin package will be also pulled and the service is going to be integrated into Apache to run on that. To achieve that, two configuration files must be deployed on the target system, and a few additional operations are needed to get everything working together. Every step is preconfigured within Ansible so that the whole process could be launched by a single command on the control node, and could be run on a single or a number of comparable target machines automatically and reproducibly. If a server is needed for trying this workshop out, straightforward cloud server instances are available on the net for example at DigitalOcean, but let me underline this there are other cloud providers which offer the same things, too! If it s needed for experiments or other purposes only for a limited time, low priced droplets are available here which are billed by the hour. After being registered, the machine(s) which is/are wanted could be set up easily over the web interface (choose Debian 8.7 as OS), but there are also command line clients available like doctl (which is not yet available as a Debian package). For the convenient use of a droplet the user should generate a SSH key pair on the local machine, first: 
$ ssh-keygen -t rsa -b 4096 -C "john@doe.com" -f ~/.ssh/mykey
The public part of the key ~/.ssh/mykey.pub then can be uploaded into the user account before the droplet is going to be created, it then could be integrated automatically. There is a good introduction on the whole process available in the excellent tutorial series serversforhackers.com, here. Ansible then can use the SSH keypair to login into a droplet without the need to type in the password every time. On a cloud server like this carrying a Debian base system, the examples in this workshop can be tried well. Ansible works client-less and doesn t need to be installed on the remote system but only on the control node, however a Python 2.7 interpreter is needed there (the base system of DigitalOcean includes that). For that Ansible can do anything on them, remote servers which are going to be controlled must be added to /etc/ansible/hosts. This is a configuration file in the INI format for DNS names and IP addresses. For a flexible organisation of the server inventory it s possible to group hosts here, IP ranges could be given, and optional variables can be used among other useful things (the default file contains a couple of examples). One or a couple of servers (in Ansible they are called hosts ) on which something particular is going to be happening (like httpbin is going to be installed) could be added like this (the group name is arbitrary): 
[httpbin]
192.0.2.0
Whether Ansible could communicate with the hosts in the group and actually can operate on them can be verified by just pinging them like this: 
$ ansible httpbin -m ping -u root --private-key=~/.ssh/mykey
192.0.2.0   SUCCESS =>  
    "changed": false, 
    "ping": "pong"
The command succeeded well, so it appears there isn t no significant problem regarding this machine. The return value changed:false indicates that there haven t been any changes on that host as a result of the execution of this command. Next to ping there are several other modules which could be used with the command line tool ansible the same way, and these modules are actually something like the core components of Ansible. The module shell for example can be used to execute shell commands on the remote machine like uname to get some system information returned from the server: 
$ ansible httpbin -m shell -a "uname -a" -u root --private-key=~/.ssh/mykey
192.0.2.0   SUCCESS   rc=0 >>
Linux debian-512mb-fra1-01 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u2 (2016-10-19) x86_64 GNU/Linux
In the same way, the module apt could be used to remotely install packages. But with that there s no major advantage over other software products that offer a similar functionality, and using those modules on the command line is just the basics of Ansible usage. Playbooks in Ansible are YAML scripts for the manipulation of the registered hosts in /etc/ansible/hosts. Different tasks can be defined here for successive processing, like a simple playbook for changing the package source from stable to testing for example goes like this: 
---
 - hosts: httpbin
   tasks:
   - name: remove "jessie" package source
     apt_repository: repo='deb http://mirrors.digitalocean.com/debian jessie main' state=absent
   - name: add "testing" package source
     apt_repository: repo='deb http://httpredir.debian.org/debian testing main contrib non-free' state=present
   - name: upgrade packages
     apt: update_cache=yes upgrade=dist
First, like used with the CLI tool ansible above, the targeted host group httpbin is chosen. The default user root and the SSH key could be fixed here, too, to spare the need to give them on the command line. Then there are three tasks defined to get worked down consecutively: With the module apt_repository the preset package source jessie is removed from /etc/apt/sources.list. Then, a new package source for the testing archive gets added to /etc/apt/sources.list.d/ by using the same module (by the way, mirrors.digitalocean.org also provides testing, though, and that might be faster). After that, the apt module is used to upgrade the package inventory (it performs apt-get dist-upgrade), after an update of the package cache has taken place (by running apt-get update) A playbook like this (the filename is arbitrary, but commonly carries the suffix .yml) can be run by the CLI tool ansible-playbook, like this: 
$ ansible-playbook httpbin.yml -u root --private-key=~/.ssh/mykey
Ansible then works down the individual plays of the tasks on the remote server(s) top-down, and due to a high speed net connection and SSD block device hardware the change of the system to being a Debian Testing base installation only takes around a minute to complete in the cloud. While working, Ansible puts out status reports for the individual operations. If certain changes on the base system have been taken place already like when a playbook is run through one more time, the modules of course sense that and return just the information that the system haven t been changed because it s already there what have been wanted to change to. Beyond the basic playbook which is shown here there are more advanced features like register and when available to bind the execution of a play to the error-free result of a previous one. The apt module then can be used in the playbook to install the three needed binary packages one after another: 
   - name: install apache2
     apt: pkg=apache2 state=present
   - name: install mod_wsgi
     apt: pkg=libapache2-mod-wsgi state=present
   - name: install httpbin
     apt: pkg=python-httpbin state=present
The Debian packages are configured in a way that the Apache web server is running immediately after installation, and the Apache module mod_wsgi is automatically integrated. If that would be otherwise desired, there are Ansible modules available for operating on Apache which can reverse this if that is wanted. By the way, after the package have been installed the httpbin server can be launched with python -m httpbin.core, but this runs only a mini web server which is not suitable for productive use. To get httpbin running on the Apache web server two configuration files are needed. They could be set up in the project directory on the control node and then uploaded onto the remote machine with another Ansible module. The file httpbin.wsgi (the name is again arbitrary) contains only a single line which is the starter for the WSGI application to run: 
from httpbin import app as application
The module copy can be used to deploy that script on the host, while the target folder /var/www/httpbin must be set up before that by the module file. In addition to that, a separate user account like httpbin (the name is also arbitrary but picked up in the other config file) is needed to run it, and the module user can set this up. The demonstrational playbook continues, and the plays which are performing these three operations are going like this: 
   - name: mkdir /var/www/httpbin
     file: path=/var/www/httpbin state=directory
   - name: set up user "httpbin"
     user: name=httpbin
   - name: copy WSGI starter
     copy: src=httpbin.wsgi dest=/var/www/httpbin/httpbin.wsgi owner=httpbin group=httpbin mode=0644
Another configuration script httpbin.conf is needed for Apache on the remote server to include the WSGI application httpbin running as a virtual host. It goes like this: 
<VirtualHost *>
 WSGIDaemonProcess httpbin user=httpbin group=httpbin threads=5
 WSGIScriptAlias / /var/www/httpbin/httpbin.wsgi
 <Directory /var/www/httpbin>
  WSGIProcessGroup httpbin
  WSGIApplicationGroup % GLOBAL 
  Order allow,deny
  Allow from all
 </Directory>
</VirtualHost>
This file needs to be copied into the folder /etc/apache2/sites-available on the host, which already exists when the apache2 package is installed. The remaining operations which are missing to get anything running together are: The default welcome screen of Apache blocks anything else and should be disabled by Apache s CLI tool a2dissite. And after that, the new virtual host needs to be activated with the complementary tool a2ensite both could be run remotely by the module command. Then the Apache server on the remote machine must be restarted to read in the new configuration. You ve guessed it already, that s all easy to perform with Ansible: 
   - name: deploy configuration script
     copy: src=httpbin.conf dest=/etc/apache2/sites-available owner=root group=root mode=0644
   - name: deactivate default welcome screen
     command: a2dissite 000-default.conf
     
   - name: activate httpbin virtual host
     command: a2ensite httpbin.conf
   - name: restart Apache
     service: name=apache2 state=restarted
That s it. After this playbook has been performed by Ansible on a (or several) freshly set up remote Debian base installation completely, then the httpbin request server is available running on the Apache web server and could be queried from anywhere by a web browser, or for example by curl: 
$ curl http://192.0.2.0/user-agent
 
  "user-agent": "curl/7.50.1"
With the broad set of Ansible modules and the playbooks a lot of tasks can be accomplished like the example problem which has been explained here. But the range of functions of Ansible however is still even more comprehensive, but to discuss that would have blown the frame of this blog post. For example the playbooks offer more advanced features like event handler which can be used for recurring operations like the restart of Apache in more extensive projects. And beyond playbooks, templates could be set up in the roles which can behave differently on selected machine groups Ansible uses Jinja2 as template engine for that. And the scope of functions of the basic modules could be expanded by employing external tools. To drop a word on why it could be useful in certain situations to run own instances of the httpbin request server instead of using the official ones which are provided on the net by Runscope: Like some people would prefer to run a private instance for example in the local network instead of querying the one on the internet. Or for some development reasons a couple or even a large number of identical instances might be needed Ansible is ideal for setting them up automatically. Anyway, the Javascript bindings to the tracking services like Google Analytics in httpbin/templates/trackingscripts.html are patched out in the Debian package. That could be another reason to prefer to set up an own instance on a Debian server.

5 March 2017

Dirk Eddelbuettel: RcppGSL 0.3.2

The RcppGSL package provides an interface from R to the GNU GSL using the Rcpp package. RcppGSL release 0.3.2 is one of several maintenance releases this weekend to fix an issue flagged by CRAN: calls to .Call() sometimes used package= where PACKAGE= was meant. This came up now while the registration mechanism is being reworked. So RcppGSL was updated too, and we took the opportunity to bring several packaging aspects up to the newest standards, including support for the soon-to-be required registration of routines. No new code or features were added. The NEWS file entries follow below:

Changes in version 0.3.2 (2017-03-04)
  • In the fastLm function, .Call now uses the correct PACKAGE= argument
  • Added file init.c with calls to R_registerRoutines() and R_useDynamicSymbols(); also use .registration=TRUE in useDynLib in NAMESPACE
  • The skeleton configuration for created packages was updated.

Courtesy of CRANberries, a summary of changes to the most recent release is available. More information is on the RcppGSL page. Questions, comments etc should go to the issue tickets at the GitHub repo.

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

Dirk Eddelbuettel: RcppSMC 0.1.5

RcppSMC provides Rcpp-based bindings to R for them Sequential Monte Carlo Template Classes (SMCTC) by Adam Johansen described in his JSS article. RcppSMC release 0.1.5 is one of several maintenance releases this weekend to fix an issue flagged by CRAN: calls to .Call() sometimes used package= where PACKAGE= was meant. This came up now while the registration mechanism is being reworked. Hence RcppSMC was updated, and we took the opportunity to bring several packaging aspects up to the newest standards, including support for the soon-to-be required registration of routines. No new code or features were added. The NEWS file entries follow below:

Changes in RcppSMC version 0.1.5 (2017-03-03)
  • Correct .Call to use PACKAGE= argument
  • DESCRIPTION, NAMESPACE, README.md changes to comply with current R CMD check levels
  • Added file init.c with calls to R_registerRoutines() and R_useDynamicSymbols()
  • Updated .travis.yml file for continuous integration

Courtesy of CRANberries, there is a diffstat report for this release. More information is on the RcppSMC page. Issues and bugreports should go to the GitHub issue tracker.

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

Julien Viard de Galbert: Raspberry Pi 3 as desktop computer

For about six months I ve been using a Raspberry Pi 3 as my desktop computer at home. The overall experience is fine, but I had to do a few adjustments.
First was to use KeePass, the second to compile gcc for cross-compilation (ie use buildroot).
KeePass I m using KeePass + KeeFox to maintain my passwords on the various websites (and avoid reusing the same everywhere).
For this to work on the Raspberry Pi, one need to use mono from Xamarin: 
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb http://download.mono-project.com/repo/debian wheezy main"   sudo tee /etc/apt/sources.list.d/mono-xamarin.list
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install mono-runtime
The install instruction comes from mono-project and the initial pointer was found on raspberrypi forums, stackoverflow and Benny Michielsen s blog.
And for some plugin to work I think I had to apt-get install mono-complete. Compiling gcc Using the Raspberry Pi 3, I recovered an old project based on buildroot for the raspberry pi 2. And just for building the tool-chain I had a few issues. First the compilation would stop during mnp compilation: 
 /usr/bin/gcc -std=gnu99 -c -DHAVE_CONFIG_H -I. -I.. -D__GMP_WITHIN_GMP -I.. -DOPERATION_divrem_1 -O2 -Wa,--noexecstack tmp-divrem_1.s -fPIC -DPIC -o .libs/divrem_1.o
tmp-divrem_1.s: Assembler messages:
tmp-divrem_1.s:129: Error: selected processor does not support ARM mode  mls r1,r4,r8,r11'
tmp-divrem_1.s:145: Error: selected processor does not support ARM mode  mls r1,r4,r8,r11'
tmp-divrem_1.s:158: Error: selected processor does not support ARM mode  mls r1,r4,r8,r11'
tmp-divrem_1.s:175: Error: selected processor does not support ARM mode  mls r1,r4,r3,r8'
tmp-divrem_1.s:209: Error: selected processor does not support ARM mode  mls r11,r4,r12,r3'
Makefile:768: recipe for target 'divrem_1.lo' failed
make[]: *** [divrem_1.lo] Error 1
I Googled the error and found this post on the Raspberry Pi forum not really helpful
But I finally found an explanation on Jan Hrach s page on the subject.
The raspbian distribution is still optimized for the first Raspberry Pi so basically the compiler is limited to the old raspberypi instructions. While I was compiling gcc for a Raspberry Pi 2 so needed the extra ones. The proposed solution is to basically update raspbian to debian proper. While this is a neat idea, I still wanted to get some raspbian specific packages (like the kernel) but wanted to be sure that everything else comes from debian. So I did some apt pinning. First I experienced that pinning is not sufficient so when updating source.list with plain debian Jessie, make sure to add theses lines before the raspbian lines: 
# add official debian jessie (real armhf gcc)
deb http://ftp.fr.debian.org/debian/ jessie main contrib non-free
deb-src http://ftp.fr.debian.org/debian/ jessie main
deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main
deb http://ftp.fr.debian.org/debian/ jessie-updates main
deb-src http://ftp.fr.debian.org/debian/ jessie-updates main
Then run the following to get the debian gpg keys, but don t yet upgrade your system: 
apt update
apt install debian-archive-keyring
Now, let s add the pinning.
First if you were using APT::Default-Release "stable"; in your apt.conf (as I did) remove it. It does not mix well with fine grained pinning we will then implement. Then, fill your /etc/apt/preferences file with the following: 
# Debian
Package: *
Pin: release o=Debian,a=stable,n=jessie
Pin-Priority: 700
# Raspbian
Package: *
Pin: release o=Raspbian,a=stable,n=jessie
Pin-Priority: 600
Package: *
Pin: release o=Raspberry Pi Foundation,a=stable,n=jessie
Pin-Priority: 600
# Mono
Package: *
Pin: release v=7.0,o=Xamarin,a=stable,n=wheezy,l=Xamarin-Stable,c=main
Pin-Priority: 800
Note: You can use apt-cache policy (no parameter) to debug pinning.
The pinning above is mainly based on the origin field of the repositories (o=)
Finally you can upgrade your system: 
apt update 
apt-cache policy gcc 
rm /var/cache/apt/archives/* 
apt upgrade 
apt-cache policy gcc
Note: Removing the cache ensure we download the packages from debian as raspbian is using the exact same naming but we now they are not compiled with a real armhf tool-chain. Second issue with gcc The build stopped on recipe for target 's-attrtab' failed. There are many references on the web, that one was easy, it just need more memory, so I added some swap on the external SSD I was already using to work on buildroot. Conclusion That s it for today, not bad considering my last post was more that 3 years ago

Vincent Bernat: Netops with Emacs and Org mode

Org mode is a package for Emacs to keep notes, maintain todo lists, planning projects and authoring documents . It can execute embedded snippets of code and capture the output (through Babel). It s an invaluable tool for documenting your infrastructure and your operations. Here are three (relatively) short videos exhibiting Org mode use in the context of network operations. In all of them, I am using my own junos-mode which features the following perks: Since some Junos devices can be quite slow, commits and remote executions are done asynchronously1 with the help of a Python helper. In the first video, I take some notes about configuring BGP add-path feature (RFC 7911). It demonstrates all the available features of junos-mode.
Youtube video cover e9sjhbxWJNE
In the second video, I execute a planned operation to enable this feature in production. The document is a modus operandi and contains the configuration to apply and the commands to check if it works as expected. At the end, the document becomes a detailed report of the operation.
Youtube video cover jCH-gO7RfFE
In the third video, a cookbook has been prepared to execute some changes. I set some variables and execute the cookbook to apply the change and check the result.
Youtube video cover L0G72g7R-xY
  1. This is a bit of a hack since Babel doesn t have native support for that. Also have a look at ob-async which is a language-independent implementation of the same idea.

4 March 2017

intrigeri: Contribute your skills to Debian in Paris, May 13-14 2017

(There is a French translation of this announcement.) Join us in Paris, on May 13-14 2017, and we will find a way in which you can help Debian with your current set of skills! You might even learn one or two things in passing (but you don't have to). Debian is a free operating system for your computer. An operating system is the set of basic programs and utilities that make your computer run. Debian comes with dozens of thousands of packages, precompiled software bundled up for easy installation on your machine. A number of other operating systems, such as Ubuntu and Tails, are based on Debian. The upcoming version of Debian, called Stretch, will be released later this year. We need you to help us make it awesome :) Whether you're a computer user, a graphics designer, or a bug triager, there are many ways you can contribute to this effort. We also welcome experience in consensus decision-making, anti-harassment teams, and package maintenance. No effort is too small and whatever you bring to this community will be appreciated. Here's what we will be doing: Goals and principles Before diving into the exact content of this event, a few words from the organization team. This is a work in progress, and a statement of intent. Not everything is organized and confirmed yet. We want to bring together a heterogeneous group of people. This goal will guide our handling of sponsorship requests, and will help us make decisions if more people want to attend than we can welcome properly. In other words: if you're part of a group that is currently under-represented in computer communities, we would like you to be able to attend. We are committed to providing a friendly, safe and welcoming environment for all, regardless of level of experience, gender, gender identity and expression, sexual orientation, disability, personal appearance, body size, race, ethnicity, age, religion, nationality, or other similar personal characteristic. Attending this event requires reading and respecting our Code of Conduct, that sets the standards in terms of behaviour for the whole event, including communication (public and private) before, while and after. There will be a team ready to act if you feel you have been or are being harassed or made uncomfortable by an attendee. We believe that money should not be a blocker for contributing to Debian. We will sponsor travel and find a place to sleep for as many enthusiastic attendees as possible. The space where this event will take place is accessible to wheelchairs. We are trying to organize a translation into (probably French) sign language. Vegan food should be provided for lunch. If you have any specific needs regarding food, please let us know when registering, and we will do our best. What we will be doing There will be a number of stations, i.e. physical space dedicated to people with a given set of skills, hosted by someone who is ready to make this space welcoming and productive. A few stations are already organized, and are described below. If you want to host a station yourself, or would like us to organize another one, please let us know. For example, you may want to assess the state of Debian Stretch for a specific field of interest, be it audio editing, office work, network auditing or whatever you are doing with Debian :) Test the upcoming version of Debian We will test Debian Stretch and gather feedback. We are particularly interested in: Experienced Debian contributors will be ready to relay this feedback to the relevant teams so it is put to good use. Hypra collaborators will be there to bring a focus on universal access technologies. Design and graphics Truth be told, Debian lacks people who are good at design and graphics. There are definitely a good number of low-hanging fruits that can be tackled in a week-end, either in Debian per-se, or in upstream) projects, or in Debian derivatives. This station will be hosted by Juliette Belin. She designed the themes for the last two versions of Debian. Triage Release Critical bugs Bugs flagged as Release Critical are blocking the release of the upcoming version of Debian. To fix them, it helps to make sure the bug report documents the up-to-date status of the bug, and of its resolution. One does not need to be a programmer to do this work! For example, you can try and reproduce bugs in software you use... or in software you will discover. This helps package maintainers better focus their work. This station will be hosted by Solveig. She has experience in bug triaging, in Debian and elsewhere. Cyril Brulebois, a long-time Debian developer, will provide support and advice upon request. Fix Release Critical bugs There will be a Bug Squashing Party. Where? When? How to register? See https://wiki.debian.org/BSP/2017/05/fr/Paris for the exact address and time. Please register by the end of March if you want to attend this event! If you have any questions, please get in touch with us.

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