Search Results: "reg"

24 June 2013

Vincent Sanders: A picture is worth a thousand words

When Sir Tim made a band the first image on the web back in 1992, I do not imagine for a moment he understood the full scope of what was to follow. I also do not imagine Marc Andreessen understood the technical debt he was about to introduce and that fateful day in 1993 when he proposed the img tag allowing inline images.

Many will argue of course that the old adage of my title may not apply to the web, where if it were true, every page view would be like reading a novel! and many of those novels would involve cats or one pixel tall colour gradients.

Leaving aside the philosophical arguments for a moment it takes web browser author a great deal of effort to quickly and efficiently put those cat pictures in front of your eyeballs.
NavigatingImages are navigated by a user in a selection of ways, including:
Whatever the method, the resulting object is subject to the same caching operations as any content object within a browser. These caching and storage operations are not specific to images however images are one of the most resource intensive objects a browser must regularly deal with (though javascript and stylesheet sources are starting to rival it at times) because they are relatively large and numerous.
Pre render processing
When the image object fetch is completed the browser must process the image for rendering which is where this gets even more complicated. I shall use how this works in NetSurf as I know that browsers internals best, but operation is pretty similar in many browsers.

The content fetch will have performed basic content sniffing to determine the received objects mime type. This is necessary because a great number of servers are misconfigured and a disturbingly large number of images served as png are really jpegs etc. Indeed sometimes you even get files served which are not images!

Upon receipt of enough data to decode the image header, for the detected mime type, the images metadata is extracted. This metadata usually includes things like size and colour depth.

If the img tag in the original source document omitted the width or height of the image the entire document render may have to be reflowed at this point to allow the correct spacing. The reflow process is often unsightly and should be avoided. Additionally at this stage if the image is too large to handle or an unhandled format the object will be replaced with the "broken" image icon.

Often that will be everything that is done with the image, when I added "lazy" image conversion to NetSurf we performed extensive profiling and discovered well over 40% of images on visited pages are simply never viewed by the user but that small (100 pixel on a side) images were almost always displayed.

This odd distribution comes down to how images are used in modern web pages, they broadly fall into two categories of "decoration" and "content" for example all the background gradients and sidebar images etc. are generally small images used as decoration whereas the cat picture above is part of the "content". A user may not scroll down a page to see content but almost always gets to "view" the decoration.
Rendering
Created by Andrea R used under CC Attribution-NonCommercial-ShareAlike 2.0 licence
The exact browser heuristics used differ as to when the render operation is performed but they all have a similar job to perform. When i say render here this may be possibly as an "off screen" view if they are actually on another tab etc. Regardless the image data must be converted from the source data (a PNG, JPEG etc.) into a format suitable for the browsers display plotting routines.

The browser will create a render bitmap in whatever format the plotting routines require (for example the GTK plotters use a Cairo image surface) , use an image library to unpack the source image data (PNG) into the render bitmap (possibly performing transforms such as scaling and rotation) and then use that bitmap to update the pixels on screen.

The most common transform at render time is that of scaling, this can be problematic as not all image libraries have output scaling capabilities which results in having to decode the entire source image and then scaling from that bitmap.

This is especially egregious if the source image is large (perhaps a multi megabyte jpeg) but the width and height are set to produce a thumbnail. The effect is amplified if the user has set the image cache size limit to a small value like 8 Megabytes (yes some users do this apparently their machines have 32MB of RAM and they browse the web)

In addition the image may well require tiling (for background gradients) and quite complex transforms (including rotation) thanks to CSS 3. Add in that javascript can alter the css style and hence the transform and you can imagine quite how complex the renderers can become.
CachingThe keen reader might spot that repeated renderings of the source image (e.g. because window is scrolled or clipped) result in this computationally expensive operation also being repeated. We solve this by interposing a render image cache between the source data and the render bitmaps.

By keeping the data in the preferred format, image rendering performance can be greatly increased. It should be noted that this cache is completely distinct from the source object cache and relates only to the rendered images.

Originally NetSurf used to perform the render conversion for every image as it was received without exception, rather than at render time, resulting in a great deal of unnecessary processing and memory usage. This was originally done for simplicity and optimising for "decoration" images.

The rules for determining what gets cached and for how long are somewhat involved and the majority of the code within the current implementation NetSurf uses is metrics and statistic generation to produce better decisions.

There comes a time at which this cache is no longer sufficient and rendering performance becomes unacceptable. The NetSurf renderer errs on the side of reducing resource usage (clearing the cache) at the expense of increased render times. Other browsers make different compromises based on the expected resources of the user base.
FinallyHopefully that gives a reasonable overview to the operations a browser performs just to put that cat picture in front of your eyeballs.

And maybe next time your browser is guzzling RAM to plot thousands of images you might have a bit more appreciation to exactly what it is up to.

23 June 2013

Gregor Herrmann: RC bugs 2013/24-25

thanks to lucas & his trainees, we're seeing archive rebuilds & tons of new RC bugs again. besides that, there are still some patches in the BTS. here goes my list of recently worked on bugs; most of them in the pkg-perl group

22 June 2013

Benjamin Mako Hill: Iceowl s Awesome New Icon

If you re a Debian user, you are probably already familiar with some of the awesome icons for IceWeasel (rebranded Mozilla Firefox), IceDove (rebranded Mozilla Thunderbird) and IceApe (rebranded Mozilla SeaMonkey).

iceweasel_icon-200pxicedove_icon-200px iceape_icon-200px I was pretty ambivalent about the decision to rebrand Firefox until I saw some of proposed the IceWeasel icons which in my humble opinion were just too cute, and awesome, to pass up.

iceweasel-old Until very recently however, IceOwl (rebranded Mozilla Sundbird) had no such awesome icon. Quite a while ago, I filed bug #658664 in Debian complaining that iceowl does not include awesome icy owl icons. I wrote:

I was extremely disappointed when I installed Iceowl and discovered that it does not ship with an awesome logo or icons showing a picture of an IceOwl. Instead, it seems to be represented by picture of a (boring) paper calendar which is very generic and not awesome at all. IceWeasel, IceDove, and IceApe each include extremely awesome logos/icons that have really cool looking white illustrations of icy weasels, doves, and apes. IceOwl needs a similarly awesome logo to use as its icon. This bug seems particularly egregious because owls actually live in icy climates and come in white versions! For example: https://commons.wikimedia.org/wiki/File:Snowy_Owl_-_Schnee-Eule.jpg While illustrators need to imagine what an ice ape or ice weasel might look like, there is no such need for imagination in the case of an ice owl! As far as I m concerned, this bug should be release critical. Hopefully, someone will upload a patch quickly!
Finally, after many months of all of us suffering in silence, Nick Morrott came along and fixed the bug with the creation of this new, incredibly awesome, icy owl logo!

iceowl_icon-350px

21 June 2013

Joachim Breitner: Haskell and Debian talk at HaL8

I just finished my Haskell und Debian talk at the Haskell-Workshop HaL8 in Leipzig. Unfortunately I was thrown a off track by time constraints and since there were much less beginners and interested visitors in the audience than I had anticipated, so I skipped some parts and improvised others somewhat chaotically, so the presentation was not up to the standards that I expect from my talks. If you have attended (or if you have not) I recommend you have a look at the extended abstract (in German), which contains what I skipped and is much clearer than what I said.

Dirk Eddelbuettel: Upcoming Rcpp talk in Sydney

The Sydney Users of R Forum (SURF) will be hosting me for a talk on July 10. The focus will be Rcpp for R and C++ integration, and the intent is to have this be really applied with lots of motivating examples. Organizers Louise and Eugene were able to move this to a slightly larger room as the initial capacity of 50 was filled almost immediately. As of right now, the talk page shows a few available slots. If you're in the Sydney are in early July, why not register and swing by? If you're not in the area, the Rcpp Events page lists other upcoming talks too.

19 June 2013

DebConf team: DebConf13 DebCamp confirmation and opening of the reconfirmation period (Posted by Didier Raboud)

Going to DebConf13!
DebConf13 DebCamp confirmed! The DebConf Team is very pleased to announce that DebCamp will be open for almost a full week in August. DebCamp will start on Tuesday 6 August 2013 at the main conference venue, Le Camp, and will be immediately followed by DebConf13, starting Sunday 11th August. Opening of the reconfirmation period As the DebConf Registration Team have announced on debconf-announce (to which you should really be subscribed), now is the time to reconfirm your attendance to DebConf13 (and actually register to DebCamp). This is really important for final calculations of food, room and costs, please read the announcement for all the important details. The reconfirmation period is open until the 30 June 2013. We look forward to seeing everyone in August in Vaumarcus. The DebConf team

Daniel Pocock: Australia's war on brains (and immigration)

Some weeks ago, our Prime Minister was slashdotted when she suspended her usual racist attacks on refugees to attack foreign IT workers and the companies that employ them with absurd accusations of "rorts" and "stealing" jobs. Today, she's introduced new laws in the parliament aiming to further bastardization of intelligent, skilled and educated workers and anybody who associates with them, including Australian employers. Unwarranted attention on a minority of IT workers This is not just some random bill before the parliament. There are just two weeks left before the parliament concludes and an election campaign begins. It is clear that what we are seeing now is the Real Julia coming though, choosing to make the small minority of foreign workers in our country at the center of people's thoughts as they go to vote in September. A debt of gratitude to foreign workers These verses from our national anthem, Advance Australia Fair say a lot about how Australia became what it is today:
For those who've come across the seas

We've boundless plains to share;

With courage let us all combine

To Advance Australia Fair.
The last 200 years of Australia's history has been a story of immigration. It is not something to be afraid of: our forefathers celebrated it. Foreign workers: why Australia needs you Australia has had some appalling flops in IT and engineering: There is no doubt in my mind that additional foreign workers would have made a positive contribution to all of these problems or can do so in the future. The sun never sets on IT Every day, I collaborate with dozens of IT specialists all over the world through the virtual workplace that is the Internet, particularly in the free and open source software community. Many of these people, I've never even met and in most cases I don't even know where they are, where they were born or what is the colour of their skin. Those details wouldn't make any difference to the way that we work in IT today. How many IT managers have time to waste dealing with more real world bureaucracy when they've experienced online, global productivity? How many IT workers feel demotivated by having to explain trivial details about their personal life to a Government bureaucrat who doesn't understand their skills and just looks at their colour? If you think about it, any immigration officer who really understands IT wouldn't be an immigration officer. They would be working in IT themselves. Immigration officers, who don't understand IT, are now going to be further empowered to bully companies away from employing some talented workers on the basis of race or nationality. Hiring managers will be intimidated into these prejudiced and biased decisions by delays, processing fees and invasive demands for sensitive documents about business planning and recruitment strategies. Australia's immigration system already has a horrendous reputation. Any visa application seems to take more than a year: no small company can keep a job position vacant that long. Families can't plan their children's schooling. Other life events come and go. There are exhorbitant fees, 1000% higher than in other western countries. Fewer and fewer self-respecting skilled workers are willing to put their spouses and children through the degrading medical examinations. Judging the impact of poor immigration policy While the economic impact of this immigration mess on industry is hard to quantify with an exact figure, we can take some insight from the education system. As the visa system has been hijacked by racists over the last 10 years, there has been a dramatic fall in participation (and revenues) from foreign students. In one year, enrolments (and revenue) fell 30%. This is not just bad for the balance sheets of the universities, it also means that in a future where commerce is global, Australians are more and more isolated and inexperienced culturally. IT workers and their employers have plenty of choices: Australia's close neighbor, Singapore, is one of them. Visas are granted in 2 weeks, no degrading medical exam required, low taxes and tropical sunshine all year round. Many companies that find it impractical to deal with Australia's bureaucracy end up moving their best Australian workers to places like Singapore to be part of a global team. This can't be good for the workforce that is left behind without jobs. The training delusion Government officials continue to rant and rave about companies failing to train Australian workers. The new laws supposedly force companies to "fix" this problem and train Australian workers. This, too, is a delusion: employers are not to blame. Some of the best Australian workers are already long gone to places like Singapore, London and the US. With talented foreign workers denied the opportunity to come and fill the void, there is less opportunity for skills to be acquired by more junior workers in Australian workplaces. It is also extremely difficult for more junior workers to get a foot in the door in the international job market and the primary reason for this is the Australian Government's failure to fund university programs beyond a bachelor's degree. Compare this to Europe and the US where all competent graduates are funded through to a Masters or PhD program. The bottom line is that more junior workers are denied the opportunity to get the best training either at home or abroad and in both cases it's not the foreign workers that can be blamed: it's the Government's own fault. Why do we need skilled foreign workers when Australians can win Nobel Prizes? The Australian press recently went into a frenzy when an Australian won the Nobel Prize for physics. There was a catch though: he's a migrant from the United States (just don't tell the Prime Minister). Dr. Schmidt migrated to Australia 20 years ago when the immigration system was not the same as today. Today, future Nobel Prize winners are being shown a brick wall - maybe we even have one of them rotting away in our death camps or left in the sea for sharks to eat. The BBC recently revealed that Britain's successor to Stephen Hawking may be a young girl who migrated from India - it is chilling to imagine where a child like this may be hidden away under Australia's immigration system. Bureaucracy leads to fraud and exploitation It's been clearly demonstrated that wherever you have elaborate, artificial systems of bureaucracy it leads to inefficiency, it suppresses innovation and in the worst cases it enables fraud and exploitation. The typical examples usually involve police in some third-world African nation setting up road blocks and collecting fees from travellers who want to pass the queues. This type of opportunism has also been found in Australia's immigration system, with one Federal politician already directly implicated and jailed for his role in a visa racket. Gillard's own bullet man A Queensland pensioner made international headlines recently when he was caught sending bullets in the mail to the Prime Minister. His demands were clear: stop immigration. While most world leaders refuse to let nutcases like this dictate their actions, Gillard appears to have been transcribing his racist letters directly into these newest immigration laws. It is a sad reality that Australian politics regularly seeks to appeal to the worst instincts in people like bullet man. The ultimate political failure When politicians stoop to the level of demonizing immigrants it is usually a clue that the politicians themselves are past their use-by dates and out of fresh policy ideas. When former French president Sarkozy tried to play the racist card in his campaign for re-election, it bit him in the bum and he was swept from power by the socialists. As always in politics, there is an element of hypocrisy at work: neither our Head of Government (the Prime Minister) nor our Head of State (the Queen) was born in Australia. Gillard was born in Wales and migrated to Australia as a child. If Australians don't vote for her in September, will she be given 28 days notice to pack her bags and go back home'? From the frying pan and into the fire Tony Abbott, Australia's would-be Prime Minister contemplating his colleague's statements on bestiality The scariest thing is that if Australians see through this racist charade and refuse to vote for it, we could end up with something equally obnoxious: the other major political party is now gaining worldwide attention for their campaign linking gay marriage and homosexuals to bestiality. Which prejudice is the lesser evil: racism or homophobia?

18 June 2013

Pietro Abate: Bootstrapping Software Distributions

The paper Bootstrapping Software Distributions , co-authored with Johannes Schauer has been accepted for publication in the proceedings of CBSE 2013, Vancouver, Canada, June 17-21, 2013.

AbstractNew hardware architectures and custom co-processor extensions are introduced to the market on a regular basis. While it is relatively easy to port a proprietary software stack to a new platform, FOSS distributions face major challenges. Bootstrapping distributions proved to be a yearlong manual process in the past due to a large amount of dependency cycles which had to be broken by hand. In this paper we propose an heuristic-based algorithm to remove build dependency cycles and to create a build order for automatically bootstrapping a binary based software distribution on a new platform.

Tollef Fog Heen: An otter, please (or, a better notification system)

Recently, there's been discussions on IRC and the debian-devel mailing list about how to notify users, typically from a cron script or a system daemon needing to tell the user their hard drive is about to expire. The current way is generally "send email to root" and for some bits "pop up a notification bubble, hoping the user will see it". Emailing me means I get far too many notifications. They're often not actionable (apt-get update failed two days ago) and they're not aggregated. I think we need a system that at its core has level and edge triggers and some way of doing flap detection. Level interrupts means "tell me if a disk is full right now". Edge means "tell me if the checksums have changed, even if they now look ok". Flap detection means "tell me if the nightly apt-get update fails more often than once a week". It would be useful if it could extrapolate some notifications too, so it could tell me "your disk is going to be full in $period unless you add more space". The system needs to be able to take in input in a variety of formats: syslog, unstructured output from cron scripts (including their exit codes), snmp, nagios notifications, sockets and fifos and so on. Based on those inputs and any correlations it can pull out of it, it should try to reason about what's happening on the system. If the conclusion there is "something is broken", it should see if it's something that it can reasonably fix by itself. If so, fix it and record it (so it can be used for notification if appropriate: I want to be told if you restart apache every two minutes). If it can't fix it, notify the admin. It should also group similar messages so a single important message doesn't drown in a million unimportant ones. Ideally, this should be cross-host aggregation. The notifications should be possible to escalate if they're not handled within some time period. I'm not aware of such a tool. Maybe one could be rigged together by careful application of logstash, nagios, munin/ganglia/something and sentry. If anybody knows of such a tool, let me know, or if you're working on one, also please let me know.

15 June 2013

Gregor Herrmann: should I feel dirty now?

I've set up a windows machine yesterday (& today since this takes so long). on my own old laptop. at home. & it's running in my apartment. feels strange after living in windows-free apartments for quite some years. & I'm still not sure how I feel about it. the purpose of resurrecting my old laptop is to run a CPAN smoke tester. there are constant complaints in the perl community about the low amount of test reports from windows installations (& for older distributions, so I'm running CPAN::Reporter::Smoker with 'reverse' => 1, at least once). for the time being, I'm using non-free software to improve free software. let's see how this develops ps: I'm also running a CPAN smoke tester on my raspberry pi (under raspbian with a perlbrewed perl) since a few days. it's a bit slow but well :)

13 June 2013

Bits from Debian: Remove unofficial debian-multimedia.org repository from your sources

The unofficial third party repository Debian Multimedia stopped using the domain debian-multimedia.org some months ago. The domain expired and it is now registered again by someone unknown to Debian. (If we're wrong on this point, please sent us an email so we can take over the domain! ;) ) This means that the repository is no longer safe to use, and you should remove the related entries from your sources.list file. After all, the need of an external repository for multimedia related packages has been greatly reduced with the release of Wheezy, which features many new and updated codecs and multimedia players. Not sure if you're using the debian-multimedia repository? You can easily check it by running: grep -i debian-multimedia.org /etc/apt/sources.list /etc/apt/sources.list.d/* If you can see debian-multimedia.org line in output, you should remove all the lines including it.

12 June 2013

Dominique Dumont: Improving error messages of Dpkg dependency parser

Hello Config::Model::Dpkg project (a Debian source package model based on Config::Model) is partly based on a ParseRec::Descent grammar. This grammar is used to parse the dependency of a Debian source package. This article will show how such a grammar is written, its limitation regarding error handling and how to improve the situation. Debian package main data is described in debian/control file. This file can feature a list of dependencies, i.e. a list of package that must be installed for the package to work. These dependencies are declared in fields like Build-Depends , or Depends as a list of package. For Dpkg model purpose, I needed only to parse one item of a dependency list at a time. This dependency item can be a simple package name: foo or a package name with a version requirement: foo ( > 1.24 ) or a package name with architectures restrictions: foo [alpha amd64 hurd-arm linux-armeb] or both: foo ( > 1.24 ) [alpha amd64 hurd-arm linux-armeb] or a list of alternate choices combining the possibilities above: foo ( > 1.24 ) bar [ linux-any] baz ( << 3.14 ) [ ! hurd-armel !hurd-armeb ] or a variable that is replaced during package build: $ perl-depends Writing a Parse::RecDescent grammar to parse this is relatively straightforward. The first production handles alternate dependencies separated by and raises an error if some text was not consumed by the dependencies: 
dependency_item: depend(s /\ /) eofile
A dependency as explained above is expressed as: 
depend: pkg_dep   variable
A variable like $ foo or $ bar -1.24~ is parsed with: 
variable: /\$ [\w:\-]+ [\w\.\-~+]*/
This rule handles a package name with optional version or arch restriction: 
pkg_dep: pkg_name dep_version(?) arch_restriction(?) 
pkg_name: /[a-z0-9][a-z0-9\+\-\.]+/
The remaining rules are quite simple: 
dep_version: '(' oper version ')' 
oper: '<<'   '<='   '='   '>='   '>>'
version: variable   /[\w\.\-~:+]+/
arch_restriction: '[' arch(s) ']'
arch:  /!?[\w-]+/
eofile: /^\Z/
The grammar above works well to parse the dependency. You can test it with this small Perl script: 
#!/usr/bin/perl
use strict;
use warnings;
use 5.010 ;
use Parse::RecDescent ;
my $parser = Parse::RecDescent->new(join('',));
my $dep = shift ;
say "parsing '$dep'";
my $ret = $parser->dependency_item($dep) ;
say "result is ", $ret if $ref ;
__DATA__
# insert grammar here !!!
Unfortunately, any error in the optional parts (i.e version requirements and arch restriction) leads to an error message which is not very helpful. The error message only mention that some text could not be parsed: 
parsing 'foo ( != 1.24 )   bar'
       ERROR (line 1): Invalid dependency item: Was expecting /\ / but found
                       "( != 1.24 )   bar" instead
or 
parsing 'foo [ arm & armel]   bar'
       ERROR (line 1): Invalid dependency item: Was expecting /\ / but found
                       "[ arm & armel]   bar" instead
The problem comes from the fact that version requirements or arch restrictions are optional. For instance if a version requirement has a syntax error, Parse::RecDescent will try to parse it as an arch restriction. This arch restriction rule will also fail and the last terminal ( eofile ) will fail. So the error message does not hint at the actual syntax problem. To generate better error messages, I improved the suggestion made in Parse::RecDescent FAQ. Instead of calling a plain subroutine, I use a sub reference that will store the error messages in a closure. This sub ref is declared in a start-up action. Note that the sub ref explicitly returns undef. I ll explain why later. 
 
    my @dep_errors ;
    my $add_error = sub  
        my ($err, $txt) = @_ ;
        push @dep_errors, "$err: '$txt'" ;
        return ;
      ;
The following production always fails while ensuring that the error list is reset. This production is always run at the beginning of the dependency parsing: 
dependency:   @dep_errors = ();
Here s the actual dependency production that is run when dependency method is called on the parser. It will return an array ref containing (1, data) if the dependency is valid or (0, errors) otherwise: 
dependency: depend(s /\ /) eofile
   
    $return = [ 1 , @ $item[1]  ] ;
   
   
   
    push( @dep_errors, "Cannot parse: '$text'" ) unless @dep_errors ;
    $return =  [ 0, @dep_errors ];
The following productions don t change much: 
depend: pkg_dep   variable
variable: /\$ [\w:\-]+ [\w\.\-~+]*/
pkg_dep: pkg_name dep_version(?) arch_restriction(?) 
dep_version: '(' oper version ')'
The first rule of this production parses the package name which must be followed by a space, end of string ( or ['. A positive look-ahead assertion is used so only the package name is consumed. If the first rule fails, the second rule provides a meaningful error message. The second rule will match anything which is not a space and create an error message. Since $add_error returns undef, the second rule returns undef and the production fails. So the text stored in the error message is not consumed: 
pkg_name: /[a-z0-9][a-z0-9\+\-\.]+(?=\s \Z \( \[)/
      /\S+/   $add_error->("bad package name", $item[1]) ;
The same trick is used with these productions: 
oper: '<<'   '='   '>>'
      /\S+/   $add_error->("bad dependency version operator", $item[1]) ; 
version: variable   /[\w\.\-~:+]+(?=\s \) \Z)/
      /\S+/   $add_error->("bad dependency version", $item[1]) ;
The action of this production is a little bit more tricky. The action ensures that '!' are either added before all arch or not at all. Otherwise an error message is generated and added to the list of errors: 
arch_restriction: '[' osarch(s) ']'
     
        my $mismatch = 0;
        # $ref contains ['!',os,arch] or ['',os,arch]
        my $ref = $item[2] ;
        for (my $i = 0; $i < $#$ref -1 ; $i++ )  
            $mismatch  = ($ref->[$i][0] xor $ref->[$i+1][0]) ;
         
        my @a = map   ($_->[0]   '') . ($_->[1]   '') . $_->[2]   @$ref ;
        if ($mismatch)  
            $add_error->("some names are prepended with '!' while others aren't.", "@a") ;
         
        else  
            $return = 1 ;
The check above is possible only if the "osarch" production returns an array ref containing something like ('!','linux','any') for "!linux-any' or ('','linux','any') for "linux-any": 
osarch: not(?) os(?) arch
     
        $return =  [ $item[1][0], $item[2][0], $item[3] ];
     
      /.?(?=\s \] \Z)/   $add_error->("bad arch specification: ", $item[1]) ;  
not: '!'
Here's the remaining of the grammar: 
os: /(any uclibc-linux linux kfreebsd knetbsd etc...)-/
     /\w+/ '-'   $add_error->("bad os in architecture specification", $item[1]) ; 
arch: / (any  alpha amd64  arm\b  arm64  etc... )
        (?=(\]  ))
      /x
        /\w+/   $add_error->("bad arch in architecture specification", $item[1]) ; 
eofile: /^\Z/
That's all for grammar 2.0... Before someone yells: "Show me the message ! ", here are some example of bad dependencies and their error message generated by the parser: 
parse 'foo ( != 1.24 )   bar'
result is: 0 bad dependency version operator: '!='
parsing 'foo [ arm & armel]   bar'
result is: 0 bad arch specification: : '&'
parsing 'foo [ arm armel ]   bar [!moo]'
result is: 0 bad arch specification: : ']' bad arch in architecture specification: 'moo'
The 2 first error messages are spot on the actual error. The second one has a false positive (']' is correct) but correctly highlights the wrong arch name ('moo'). Mission accomplished. In order to keep this post (relatively) simple, I've removed the part that actually store parsed data. They don't really matter for error handling. Nevertheless, you may see the whole grammar in Config::Model::Dpkg::Dependency module. All the best
Tagged: Config::Model, debian, dpkg, package, Parse::RecDescent, Perl

Marc 'Zugschlus' Haber: How to amd64 an i386 Debian installation with multiarch

Migrating a Debian installation between architectures has always been difficult. The recommended way to crossgrade an i386 Debian to amd64 Debian was to reinstall the system, move over data and configuration. For the more brave, in-place crossgrades usually involved chroots, rescue CDs, a lot of ar p tar xf - data.tar.gz and luck. I have never been brave when it comes to system administration, have done a lot of architecture migrations with reinstallation, and have always taken the opportunity to clear out the contamination that accumulates itself when a system is running for a long time. I would even recommend doing this to most people even now. However, I have a few very ugly systems in place that are still on i386 because I didn t dare going the reinstallation path. Doing in-place crossgrades has become a lot easier since wheezy s release, since once now can have both i386 and amd64 libraries installed in parallel, which allows to replace foo:i386 with foo:amd64 without influencing the other parts of the system. The process is still full of pitfalls: I have only tried this yet with a freshly installed minimal wheezy server system. I do not, however, expect surprises when it comes to using this process with real life systems. I will document other pitfalls I have fallen into here at a later time. My minimal wheezy system was running in a KVM VM with its virtual disk as a LVM LV in the host system. I took a snapshot before beginning and used lvconvert --merge numerous time to return my LV to the original state. Be aware that lvconvert --merge removes the snapshot after merging it, so you ll need to re-create the snapshot before trying again. During the process, I discussed things with Paul Tagliamonte, who has done this before, but on a live system and with a slightly more invasive approach. He has blogged about this. Thank you very much, your hints were very helpful. Here is a commented typescript of what I have done. Be warned: This was a lab setting with a rather minimal system. If you re going to try this with a production system, have a backup, or, if you re on snapshottable infrastructure, take snapshots and be prepared to roll back if anything goes wrong. First let s see what we have and save a list of installed packages. 
mh@swivel:~$ ssh wheezyarch.zugschlus.de
$ uname -a
Linux wheezyarch 3.9.4-zgsrv2008064 #2 SMP PREEMPT Wed Jun 5 12:57:51 UTC 2013 x86_64 GNU/Linux
$ dpkg --print-architecture
i386
$ dpkg --print-foreign-architectures
$ dpkg --list   grep i386   wc -l
175
$ dpkg --list   grep amd64   wc -l
0
$ sudo dpkg --get-selections   grep install   awk  print $1    sed  s/:.*//;s/$/:amd64
install/;  > get-selections.pre
So we have an i386 system running an x86_64 kernel. Next, we add amd64 as an additional architecture which allows us to install amd64 packages. We download the amd64 packages files. Note that dpkg still considers this an i386 system with amd64 as a foreign arch. 
$ sudo dpkg --add-architecture amd64
$ sudo apt-get update
Get:1 http://security.debian.org wheezy/updates Release.gpg [836 B]
( )
Fetched 6.155 kB in 4s (1.400 kB/s)
Reading package lists... Done
$ dpkg --print-architecture
i386
$ dpkg --print-foreign-architectures
amd64
$ dpkg --list   grep i386   wc -l
175
$ dpkg --list   grep amd64   wc -l
0
Next, download everything that is necessary to migrate dpkg and apt from i386 and amd64. We cannot directly apt things as the remove-install cycle used by apt will leave us without working dpkg. One could work around this by un-aring the dpkg.deb and directly forcing the amd64 files upon the system, but I think this approach is much cleaner. apt-get download will not resolve dependices while apt-get --download install does. After the download, dpkg --install the packages. dpkg is not particularly smart about installation order, so Pre-Depends may fail or not. If they fail, dpkg will give a list of deb files that were affected, which is an easy help to finish their installation. One could also choose the easy way (which I did here) and repeat the dpkg --install *.deb command. Since the Pre-Depends will already be installed, the second install run will succeed. 
$ sudo apt-get --download-only install dpkg:amd64 apt:amd64
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  gcc-4.7-base:amd64 libapt-pkg4.12:amd64 libbz2-1.0:amd64 libc6:amd64
  libgcc1:amd64 liblzma5:amd64 libselinux1:amd64 libstdc++6:amd64
  zlib1g:amd64
Suggested packages:
  aptitude:amd64 synaptic:amd64 wajig:amd64 dpkg-dev:amd64 apt-doc:amd64
  python-apt:amd64 glibc-doc:amd64 locales:amd64
The following packages will be REMOVED:
  apt cron-apt dpkg
The following NEW packages will be installed:
  apt:amd64 dpkg:amd64 gcc-4.7-base:amd64 libapt-pkg4.12:amd64
  libbz2-1.0:amd64 libc6:amd64 libgcc1:amd64 liblzma5:amd64 libselinux1:amd64
  libstdc++6:amd64 zlib1g:amd64
0 upgraded, 11 newly installed, 3 to remove and 0 not upgraded.
Need to get 10,0 MB of archives.
After this operation, 14,9 MB of additional disk space will be used.
Do you want to continue [Y/n]? 
Get:1 http://debian.debian.zugschlus.de/debian/ wheezy/main gcc-4.7-base amd64 4.7.2-5 [144 kB]
( )
Fetched 10,0 MB in 2s (3.535 kB/s)
Download complete and in download only mode
$ sudo dpkg --install /var/cache/apt/archives/*.deb
(Reading database ... 16586 files and directories currently installed.)
Preparing to replace apt 0.9.7.8 (using .../archives/apt_0.9.7.8_amd64.deb) ...
Unpacking replacement apt ...
dpkg: regarding .../dpkg_1.16.10_amd64.deb containing dpkg, pre-dependency problem:
 dpkg pre-depends on libbz2-1.0
dpkg: error processing /var/cache/apt/archives/dpkg_1.16.10_amd64.deb (--install):
 pre-dependency problem - not installing dpkg
Selecting previously unselected package gcc-4.7-base:amd64.
( )
Errors were encountered while processing:
 /var/cache/apt/archives/dpkg_1.16.10_amd64.deb
$ sudo dpkg --install /var/cache/apt/archives/*.deb
(Reading database ... 16905 files and directories currently installed.)
Preparing to replace apt 0.9.7.8 (using .../archives/apt_0.9.7.8_amd64.deb) ...
Unpacking replacement apt ...
( )
$
From dpkg s point of view, the system is now already amd64, with i386 being a foreign arch. However, the majory of packages is still i386. 
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
173
$ dpkg --list   grep amd64   wc -l
11
$
The apt resolver is currently in a very bad broken state since the system is missing most essential packages in its native architecture. This is not easily solved by apt-get -f install, as this would zap most of the existing system . We let apt-get --download-only -f install download the packages that it wants to replace with its amd64 counterparts and their dependencies, and, again, use dpkg --install *.deb to install them. 
$ sudo apt-get --download-only -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  cpio gettext-base:i386 klibc-utils libapt-inst1.5 libasprintf0c2:i386
  libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386 libklibc
  libreadline5:i386
Use  apt-get autoremove  to remove them.
The following extra packages will be installed:
  acpid aide bsd-mailx cpio cron curl daemon dctrl-tools exim4-base
  exim4-daemon-light initscripts insserv kbd klibc-utils less libbsd0
  libcomerr2 libcurl3 libdb5.1 libexpat1 libgcrypt11 libgdbm3 libgnutls26
  libgpg-error0 libgssapi-krb5-2 libidn11 libk5crypto3 libkeyutils1 libklibc
  libkmod2 libkrb5-3 libkrb5support0 libldap-2.4-2 liblockfile1 libncursesw5
  libnewt0.52 libp11-kit0 libpam-modules libpam0g libpcre3 libpopt0
  libreadline6 librtmp0 libsasl2-2 libslang2 libsqlite3-0 libssh2-1
  libssl1.0.0 libtasn1-3 libterm-readkey-perl libtinfo5 openssl perl
  perl-base python2.7 python2.7-minimal sysvinit-utils whiptail
Suggested packages:
  libarchive1 anacron logrotate checksecurity debtags mail-reader eximon4
  exim4-doc-html exim4-doc-info spf-tools-perl swaks bootchart2 rng-tools
  krb5-doc krb5-user libpam-doc perl-doc make python2.7-doc binutils
  binfmt-support bootlogd sash
Recommended packages:
  exim4 postfix mail-transport-agent psmisc mailx ca-certificates
  krb5-locales libgpm2 libfribidi0 libsasl2-modules libpng12-0
The following packages will be REMOVED:
  acpid:i386 aide:i386 aptitude:i386 bsd-mailx:i386 cpio:i386 cron:i386
  curl:i386 daemon:i386 dctrl-tools:i386 debsecan dmsetup:i386 e2fsprogs:i386
  exim4-base:i386 exim4-daemon-light:i386 git:i386 grub-common:i386
  grub-pc:i386 grub-pc-bin:i386 grub2-common:i386 ifupdown:i386
  initramfs-tools initscripts:i386 insserv:i386 ippl:i386 jed:i386 kbd:i386
  klibc-utils:i386 less:i386 libdevmapper-event1.02.1:i386
  libdevmapper1.02.1:i386 libklibc:i386 libnewt0.52:i386
  libparted0debian1:i386 libterm-readkey-perl:i386 lsof:i386 lvm2:i386
  molly-guard ntp:i386 openssh-server:i386 openssl:i386 parted:i386 perl:i386
  perl-base:i386 procps:i386 python-apt:i386 python2.7:i386
  python2.7-minimal:i386 rsyslog:i386 sysvinit:i386 sysvinit-utils:i386
  udev:i386 util-linux:i386 whiptail:i386
The following NEW packages will be installed:
  acpid aide bsd-mailx cpio cron curl daemon dctrl-tools exim4-base
  exim4-daemon-light initscripts insserv kbd klibc-utils less libbsd0
  libcomerr2 libcurl3 libdb5.1 libexpat1 libgcrypt11 libgdbm3 libgnutls26
  libgpg-error0 libgssapi-krb5-2 libidn11 libk5crypto3 libkeyutils1 libklibc
  libkmod2 libkrb5-3 libkrb5support0 libldap-2.4-2 liblockfile1 libncursesw5
  libnewt0.52 libp11-kit0 libpam-modules libpam0g libpcre3 libpopt0
  libreadline6 librtmp0 libsasl2-2 libslang2 libsqlite3-0 libssh2-1
  libssl1.0.0 libtasn1-3 libterm-readkey-perl libtinfo5 openssl perl
  perl-base python2.7 python2.7-minimal sysvinit-utils whiptail
0 upgraded, 58 newly installed, 53 to remove and 0 not upgraded.
Need to get 23,4 MB of archives.
After this operation, 17,5 MB disk space will be freed.
Do you want to continue [Y/n]? Y
Get:1 http://security.debian.org/debian-security/ wheezy/updates/main libgnutls26 amd64 2.12.20-7 [619 kB]
( )
Fetched 23,4 MB in 11s (2.038 kB/s)                                           
Download complete and in download only mode
$ sudo dpkg --install /var/cache/apt/archives/*.deb
(Reading database ... 16905 files and directories currently installed.)
Preparing to replace acpid 1:2.0.16-1+deb7u1 (using .../acpid_1%3a2.0.16-1+deb7u1_amd64.deb) ...
( )
Selecting previously unselected package libpam-modules:amd64.
dpkg: regarding .../libpam-modules_1.1.3-7.1_amd64.deb containing libpam-modules:amd64, pre-dependency problem:
 libpam-modules pre-depends on libdb5.1
  libdb5.1:amd64 is unpacked, but has never been configured.
dpkg: error processing /var/cache/apt/archives/libpam-modules_1.1.3-7.1_amd64.deb (--install):
 pre-dependency problem - not installing libpam-modules:amd64
Selecting previously unselected package libpcre3:amd64.
Unpacking libpcre3:amd64 (from .../libpcre3_1%3a8.30-5_amd64.deb) ...
( )
Errors were encountered while processing:
 /var/cache/apt/archives/libpam-modules_1.1.3-7.1_amd64.deb
$ sudo dpkg --install /var/cache/apt/archives/libpam-modules_1.1.3-7.1_amd64.deb
(Reading database ... 17007 files and directories currently installed.)
Unpacking libpam-modules:amd64 (from .../libpam-modules_1.1.3-7.1_amd64.deb) ...
Setting up libpam-modules:amd64 (1.1.3-7.1) ...
$ sudo apt-get clean
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
151
$ dpkg --list   grep amd64   wc -l
66
$
The concluding apt-get clean prevents packages from being reinstalled again in the next dpkg --install *.deb run. Now, the apt resolver is kind of fixed, but apt will still want to remove most of the system. I haven t found a way to get out of this mess short of allowing apt to de-install those packages and to manually install their amd64 counterparts later. First, we see what apt wants to do, and paste the The following packages will be removed part of apt-get s output into a sed expression which fixes the architecture strings for us so that we can use the resulting file as input for the following installation procedure. After that, we let apt-get do what itself considers a bad thing and requires us to type a consent sentence. The key is that this deinstallation of essential packages breaks the system, but not apt and dpkg, which allows us to un-break the system afterwards. 
$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  gettext-base:i386 libapt-inst1.5 libasprintf0c2:i386 libcurl3-gnutls:i386
  libfreetype6:i386 libfuse2:i386 libreadline5:i386
Use  apt-get autoremove  to remove them.
The following extra packages will be installed:
  sysvinit-utils:i386
Suggested packages:
  bootlogd:i386 sash:i386
The following packages will be REMOVED:
  adduser aide-common aptitude:i386 bsd-mailx console-common console-data
  console-log cron curl debian-goodies debsecan dmsetup:i386 e2fsprogs:i386
  exim4-base exim4-config exim4-daemon-light git:i386 grub-common:i386
  grub-pc:i386 grub-pc-bin:i386 grub2-common:i386 ifupdown:i386
  initramfs-tools initscripts ippl:i386 jed:i386 libcurl3
  libdevmapper-event1.02.1:i386 libdevmapper1.02.1:i386 liberror-perl
  libfile-find-rule-perl libnumber-compare-perl libparted0debian1:i386
  libswitch-perl libterm-readkey-perl libterm-readline-perl-perl
  libtext-glob-perl libtimedate-perl locales lsof:i386 lvm2:i386 molly-guard
  ntp:i386 openssh-client:i386 openssh-server:i386 openssl openssl-blacklist
  openssl-blacklist-extra parted:i386 perl perl-modules procps:i386
  python-apt:i386 rsyslog:i386 stow sysv-rc sysvinit:i386 sysvinit-utils
  tzdata ucf udev:i386 util-linux:i386
The following NEW packages will be installed:
  sysvinit-utils:i386
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  e2fsprogs:i386 util-linux:i386 (due to e2fsprogs:i386) sysvinit:i386
  sysvinit-utils tzdata (due to util-linux:i386)
0 upgraded, 1 newly installed, 62 to remove and 0 not upgraded.
Need to get 97,1 kB of archives.
After this operation, 131 MB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase  Yes, do as I say!  ? (abort with Ctrl-C)
$ sed  s/:i386//g  > removedpkg (paste  The following packages will be REMOVED:  stanza here and
type Ctrl-D afterwards)
  adduser aide-common aptitude:i386 bsd-mailx console-common console-data
  console-log cron curl debian-goodies debsecan dmsetup:i386 e2fsprogs:i386
  exim4-base exim4-config exim4-daemon-light git:i386 grub-common:i386
  grub-pc:i386 grub-pc-bin:i386 grub2-common:i386 ifupdown:i386
  initramfs-tools initscripts ippl:i386 jed:i386 libcurl3
  libdevmapper-event1.02.1:i386 libdevmapper1.02.1:i386 liberror-perl
  libfile-find-rule-perl libnumber-compare-perl libparted0debian1:i386
  libswitch-perl libterm-readkey-perl libterm-readline-perl-perl
  libtext-glob-perl libtimedate-perl locales lsof:i386 lvm2:i386 molly-guard
  ntp:i386 openssh-client:i386 openssh-server:i386 openssl openssl-blacklist
  openssl-blacklist-extra parted:i386 perl perl-modules procps:i386
  python-apt:i386 rsyslog:i386 stow sysv-rc sysvinit:i386 sysvinit-utils
  tzdata ucf udev:i386 util-linux:i386
$ cat removedpkg 
  adduser aide-common aptitude bsd-mailx console-common console-data
  console-log cron curl debian-goodies debsecan dmsetup e2fsprogs
  exim4-base exim4-config exim4-daemon-light git grub-common
  grub-pc grub-pc-bin grub2-common ifupdown
  initramfs-tools initscripts ippl jed libcurl3
  libdevmapper-event1.02.1 libdevmapper1.02.1 liberror-perl
  libfile-find-rule-perl libnumber-compare-perl libparted0debian1
  libswitch-perl libterm-readkey-perl libterm-readline-perl-perl
  libtext-glob-perl libtimedate-perl locales lsof lvm2 molly-guard
  ntp openssh-client openssh-server openssl openssl-blacklist
  openssl-blacklist-extra parted perl perl-modules procps
  python-apt rsyslog stow sysv-rc sysvinit sysvinit-utils
  tzdata ucf udev util-linux
$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  gettext-base:i386 libapt-inst1.5 libasprintf0c2:i386 libcurl3-gnutls:i386
  libfreetype6:i386 libfuse2:i386 libreadline5:i386
Use  apt-get autoremove  to remove them.
The following extra packages will be installed:
  sysvinit-utils:i386
Suggested packages:
  bootlogd:i386 sash:i386
The following packages will be REMOVED:
  adduser aide-common aptitude:i386 bsd-mailx console-common console-data
  console-log cron curl debian-goodies debsecan dmsetup:i386 e2fsprogs:i386
  exim4-base exim4-config exim4-daemon-light git:i386 grub-common:i386
  grub-pc:i386 grub-pc-bin:i386 grub2-common:i386 ifupdown:i386
  initramfs-tools initscripts ippl:i386 jed:i386 libcurl3
  libdevmapper-event1.02.1:i386 libdevmapper1.02.1:i386 liberror-perl
  libfile-find-rule-perl libnumber-compare-perl libparted0debian1:i386
  libswitch-perl libterm-readkey-perl libterm-readline-perl-perl
  libtext-glob-perl libtimedate-perl locales lsof:i386 lvm2:i386 molly-guard
  ntp:i386 openssh-client:i386 openssh-server:i386 openssl openssl-blacklist
  openssl-blacklist-extra parted:i386 perl perl-modules procps:i386
  python-apt:i386 rsyslog:i386 stow sysv-rc sysvinit:i386 sysvinit-utils
  tzdata ucf udev:i386 util-linux:i386
The following NEW packages will be installed:
  sysvinit-utils:i386
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  e2fsprogs:i386 util-linux:i386 (due to e2fsprogs:i386) sysvinit:i386
  sysvinit-utils tzdata (due to util-linux:i386)
0 upgraded, 1 newly installed, 62 to remove and 0 not upgraded.
Need to get 97,1 kB of archives.
After this operation, 131 MB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase  Yes, do as I say! 
 ?] Yes, do as I say! (actually type this!)
Get:1 http://debian.debian.zugschlus.de/debian/ wheezy/main sysvinit-utils i386 2.88dsf-41 [97,1 kB]
Fetched 97,1 kB in 0s (687 kB/s)    
(Reading database ... 17050 files and directories currently installed.)
Removing aide-common ...
( )
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing e2fsprogs ...
Removing sysv-rc ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing sysvinit ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing sysvinit-utils ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing ucf ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing libdevmapper1.02.1:i386 ...
Removing libswitch-perl ...
Removing perl ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing dmsetup ...
Removing perl-modules ...
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
Removing util-linux ...
Removing tzdata ...
Processing triggers for mime-support ...
Selecting previously unselected package sysvinit-utils.
(Reading database ... 9802 files and directories currently installed.)
Unpacking sysvinit-utils (from .../sysvinit-utils_2.88dsf-41_i386.deb) ...
Setting up sysvinit-utils (2.88dsf-41) ...
$ sudo apt-get install $(cat removedpkg)
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libasprintf0c2:i386 libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386
  libreadline5:i386
Use  apt-get autoremove  to remove them.
The following extra packages will be installed:
  e2fslibs gettext-base libapt-inst1.5 libasprintf0c2 libattr1 libblkid1
  libboost-iostreams1.49.0 libcap2 libcurl3-gnutls libcwidget3 libedit2
  libept1.4.12 libfreetype6 libfuse2 libgpm2 libncurses5 libopts25 libprocps0
  libreadline5 libsepol1 libsigc++-2.0-0c2a libss2 libudev0 libuuid1 libwrap0
  libxapian22 logrotate
Suggested packages:
  liblocale-gettext-perl tasksel debtags unicode-data anacron checksecurity
  popularity-contest xdg-utils zenity gpart e2fsck-static mail-reader eximon4
  exim4-doc-html exim4-doc-info spf-tools-perl swaks git-daemon-run
  git-daemon-sysvinit git-doc git-el git-arch git-cvs git-svn git-email
  git-gui gitk gitweb multiboot-doc grub-emu xorriso desktop-base
  isc-dhcp-client dhcp-client ppp rdnssd net-tools gpm libcwidget-dev fuse
  libparted0-dev libparted0-i18n xapian-tools ntp-doc ssh-askpass libpam-ssh
  keychain monkeysphere rssh ufw parted-doc perl-doc make libpod-plainer-perl
  python-apt-dbg python-gtk2 python-vte python-apt-doc rsyslog-mysql
  rsyslog-pgsql rsyslog-doc rsyslog-gnutls rsyslog-gssapi rsyslog-relp
  doc-base sysv-rc-conf bum bootlogd sash util-linux-locales dosfstools
Recommended packages:
  aptitude-doc-en aptitude-doc apt-xapian-index libparse-debianchangelog-perl
  exim4 postfix mail-transport-agent psmisc mailx patch rsync ssh-client
  os-prober busybox busybox-initramfs busybox-static ca-certificates
  uuid-runtime xauth ncurses-term iso-codes usbutils
The following packages will be REMOVED:
  gettext-base:i386 libboost-iostreams1.49.0:i386 libcwidget3:i386
  libept1.4.12:i386 libopts25:i386 libxapian22:i386 logrotate:i386
  sysvinit-utils:i386
The following NEW packages will be installed:
  adduser aide-common aptitude bsd-mailx console-common console-data
  console-log cron curl debian-goodies debsecan dmsetup e2fslibs e2fsprogs
  exim4-base exim4-config exim4-daemon-light gettext-base git grub-common
  grub-pc grub-pc-bin grub2-common ifupdown initramfs-tools initscripts ippl
  jed libapt-inst1.5 libasprintf0c2 libattr1 libblkid1
  libboost-iostreams1.49.0 libcap2 libcurl3 libcurl3-gnutls libcwidget3
  libdevmapper-event1.02.1 libdevmapper1.02.1 libedit2 libept1.4.12
  liberror-perl libfile-find-rule-perl libfreetype6 libfuse2 libgpm2
  libncurses5 libnumber-compare-perl libopts25 libparted0debian1 libprocps0
  libreadline5 libsepol1 libsigc++-2.0-0c2a libss2 libswitch-perl
  libterm-readkey-perl libterm-readline-perl-perl libtext-glob-perl
  libtimedate-perl libudev0 libuuid1 libwrap0 libxapian22 locales logrotate
  lsof lvm2 molly-guard ntp openssh-client openssh-server openssl
  openssl-blacklist openssl-blacklist-extra parted perl perl-modules procps
  python-apt rsyslog stow sysv-rc sysvinit sysvinit-utils tzdata ucf udev
  util-linux
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  sysvinit-utils:i386
0 upgraded, 89 newly installed, 8 to remove and 0 not upgraded.
Need to get 55.3 MB of archives.
After this operation, 134 MB of additional disk space will be used.
You are about to do something potentially harmful.
To continue type in the phrase  Yes, do as I say! 
 ?] Yes, do as I say! (actually type this!)
Get:1 http://debian.debian.zugschlus.de/debian/ wheezy/main e2fslibs amd64 1.42.5-1.1 [197 kB]
( )
Fetched 55.3 MB in 20s (2648 kB/s)                                            
perl: warning: Setting locale failed.
( )
This process may re-ask some debconf questions that you have already answered during initial system setup. I find it comforting to actually see that my answers were preserved, but you can always export DEBIAN_FRONTEND=noninteractive if you want installation to be silent. If you know how this step can be done more elegantly, please comment. We now, finally, have the resolver in a consistent state. 
$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libasprintf0c2:i386 libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386
  libreadline5:i386
Use  apt-get autoremove  to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
121
$ dpkg --list   grep amd64   wc -l
119
$
Now we can force-crossgrade all i386 packages that are still left on the system. Again, we use the apt-get --download install, dpkg --install stunt as coreutils gets crossgraded at this step and dpkg is less than happy if it finds itself without /bin/rm. Remember, with --download, nothing is actually removed during this step even if apt-get claims to remove things. Apt will also complain that many of these packages are already installed. Those are libs that were pulled in previously. The first dpkg --install run in this step will complain about gazillions of dependency problems, which will all be resolved in concluding apt-get -f install after the second dpkg --install run, this time a manual one. 
$ sudo apt-get --download-only install $(dpkg --list   awk  if( $1 ==  ii  && $4 ==
 i386  )   print $2     sed  s/:i386// )
Reading package lists... Done
Building dependency tree       
Reading state information... Done
( )
The following packages were automatically installed and are no longer required:
  libasprintf0c2:i386 libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386
  libreadline5:i386
Use  apt-get autoremove  to remove them.
Suggested packages:
  powermgmt-base bash-doc bzip2-doc diffutils-doc wdiff mlocate locate
  gnupg-doc xloadimage imagemagick eog libpcsclite1 iproute-doc resolvconf
  avahi-autoipd nfs-common ncompress indent
Recommended packages:
  bsdmainutils gnupg-curl libatm1
The following packages will be REMOVED:
  anacron:i386 apt-utils:i386 base-files:i386 base-passwd:i386 bash:i386
( )
The following NEW packages will be installed:
  anacron apt-utils base-files base-passwd bash bsdutils busybox bzip2
( )
0 upgraded, 56 newly installed, 49 to remove and 0 not upgraded.
Need to get 24,1 MB of archives.
After this operation, 2.030 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://debian.debian.zugschlus.de/debian/ wheezy/main kmod amd64 9-3 [60,5 kB]
( )
Fetched 24,1 MB in 11s (2.120 kB/s)                                           
Download complete and in download only mode
$ sudo dpkg --install /var/cache/apt/archives/*.deb
(Reading database ... 17098 files and directories currently installed.)
Preparing to replace adduser 3.113+nmu3 (using .../adduser_3.113+nmu3_all.deb) ...
Unpacking replacement adduser ...
( )
Errors were encountered while processing:
 /var/cache/apt/archives/bash_4.2+dfsg-0.1_amd64.deb
 /var/cache/apt/archives/coreutils_8.13-3.5_amd64.deb
 initscripts
 lvm2
 procps
 rsyslog
 sysvinit
 sysv-rc
 udev
 util-linux
 aide-common
 dmsetup
 e2fsprogs
 ifupdown
 initramfs-tools
 libdevmapper1.02.1:amd64
 libdevmapper-event1.02.1:amd64
 libparted0debian1:amd64
 molly-guard
 openssh-server
 parted
 grub-common
 grub-pc
 grub-pc-bin
 grub2-common
$ sudo dpkg --install /var/cache/apt/archives/bash_4.2+dfsg-0.1_amd64.deb
/var/cache/apt/archives/coreutils_8.13-3.5_amd64.deb
(Reading database ... 17129 files and directories currently installed.)
Preparing to replace bash 4.2+dfsg-0.1 (using .../bash_4.2+dfsg-0.1_amd64.deb) ...
Unpacking replacement bash ...
Preparing to replace coreutils 8.13-3.5 (using .../coreutils_8.13-3.5_amd64.deb) ...
Unpacking replacement coreutils ...
Setting up bash (4.2+dfsg-0.1) ...
update-alternatives: using /usr/share/man/man7/bash-builtins.7.gz to provide /usr/share/man/man7/builtins.7.gz
(builtins.7.gz) in auto mode
Setting up coreutils (8.13-3.5) ...
$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  libasprintf0c2:i386 libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386
  libreadline5:i386
Use  apt-get autoremove  to remove them.
The following extra packages will be installed:
  sysvinit-utils
Suggested packages:
  bootlogd sash
The following packages will be REMOVED:
  libslang2-modules:i386 sysvinit-utils:i386
The following NEW packages will be installed:
  sysvinit-utils
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  sysvinit-utils:i386
0 upgraded, 1 newly installed, 2 to remove and 0 not upgraded.
23 not fully installed or removed.
Need to get 0 B/99,5 kB of archives.
After this operation, 328 kB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase  Yes, do as I say! 
 ?] Yes, do as I say! (actually type this!)
dpkg: warning: overriding problem because --force enabled:
 This is an essential package - it should not be removed.
(Reading database ... 17129 files and directories currently installed.)
Removing sysvinit-utils ...
Selecting previously unselected package sysvinit-utils.
(Reading database ... 17105 files and directories currently installed.)
Unpacking sysvinit-utils (from .../sysvinit-utils_2.88dsf-41_amd64.deb) ...
Setting up sysvinit-utils (2.88dsf-41) ...
Setting up sysv-rc (2.88dsf-41) ...
Setting up initscripts (2.88dsf-41) ...
Setting up util-linux (2.20.1-5.3) ...
Setting up e2fsprogs (1.42.5-1.1) ...
Setting up sysvinit (2.88dsf-41) ...
sysvinit: restarting... done.
(Reading database ... 17129 files and directories currently installed.)
Removing libslang2-modules:i386 ...
Setting up ifupdown (0.7.8) ...
Setting up procps (1:3.3.3-3) ...
[ ok ] Setting kernel variables ... /etc/sysctl.conf...done.
Setting up udev (175-7.2) ...
[ ok ] Stopping the hotplug events dispatcher: udevd.
[ ok ] Starting the hotplug events dispatcher: udevd.
update-initramfs: deferring update (trigger activated)
Setting up rsyslog (5.8.11-3) ...
[ ok ] Stopping enhanced syslogd: rsyslogd.
[ ok ] Starting enhanced syslogd: rsyslogd.
Setting up aide-common (0.15.1-8) ...
Setting up initramfs-tools (0.109.1) ...
update-initramfs: deferring update (trigger activated)
Setting up openssh-server (1:6.0p1-4) ...
[ ok ] Restarting OpenBSD Secure Shell server: sshd.
Setting up molly-guard (0.4.5-1) ...
Setting up libdevmapper1.02.1:amd64 (2:1.02.74-7) ...
Setting up libdevmapper-event1.02.1:amd64 (2:1.02.74-7) ...
Setting up libparted0debian1:amd64 (2.3-12) ...
Setting up grub-common (1.99-27+deb7u1) ...
Setting up grub2-common (1.99-27+deb7u1) ...
Setting up grub-pc-bin (1.99-27+deb7u1) ...
Setting up grub-pc (1.99-27+deb7u1) ...
Installation finished. No error reported.
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.9.4-zgsrv2008064
Found initrd image: /boot/initrd.img-3.9.4-zgsrv2008064
done
Setting up parted (2.3-12) ...
Setting up dmsetup (2:1.02.74-7) ...
update-initramfs: deferring update (trigger activated)
Setting up lvm2 (2.02.95-7) ...
[ ok ] Setting up LVM Volume Groups...done.
update-initramfs: deferring update (trigger activated)
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.9.4-zgsrv2008064
Found 12 processes using old versions of upgraded files
( )
$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libasprintf0c2:i386 libcurl3-gnutls:i386 libfreetype6:i386 libfuse2:i386
  libreadline5:i386
Use  apt-get autoremove  to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
72
$ dpkg --list   grep amd64   wc -l
175
$
We have completed the actual crossgrade. All non-multiarch packages are now amd64. The resolver is now fine as well. At this current state, all i386 packages that are still installed should be unneeded libs. We can safely nuke them. Careful minds may inspect the list of packages to be removed for important or non-lib items. After completion of the command, a second call of the same command verifies that we were successful. 
$ sudo apt-get remove $(dpkg --list   awk  if( $1 ==  ii  && $4 ==  i386  )   print $2
  )
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  e2fslibs:i386 gcc-4.7-base:i386 libacl1:i386 libapt-inst1.5:i386
  libapt-pkg4.12:i386 libasprintf0c2:i386 libattr1:i386 libblkid1:i386
  libbsd0:i386 libbz2-1.0:i386 libc6:i386 libcap2:i386 libcomerr2:i386
  libcurl3:i386 libcurl3-gnutls:i386 libdb5.1:i386 libedit2:i386
  libexpat1:i386 libfreetype6:i386 libfuse2:i386 libgcc1:i386
  libgcrypt11:i386 libgdbm3:i386 libgnutls26:i386 libgpg-error0:i386
  libgpm2:i386 libgssapi-krb5-2:i386 libidn11:i386 libk5crypto3:i386
  libkeyutils1:i386 libkmod2:i386 libkrb5-3:i386 libkrb5support0:i386
  libldap-2.4-2:i386 liblockfile1:i386 liblzma5:i386 libmagic1:i386
  libncurses5:i386 libncursesw5:i386 libp11-kit0:i386 libpam-modules:i386
  libpam0g:i386 libpci3:i386 libpcre3:i386 libpng12-0:i386 libpopt0:i386
  libprocps0:i386 libreadline5:i386 libreadline6:i386 librtmp0:i386
  libsasl2-2:i386 libselinux1:i386 libsemanage1:i386 libsepol1:i386
  libsigc++-2.0-0c2a:i386 libslang2:i386 libsqlite3-0:i386 libss2:i386
  libssh2-1:i386 libssl1.0.0:i386 libstdc++6:i386 libtasn1-3:i386
  libtinfo5:i386 libudev0:i386 libusb-0.1-4:i386 libustr-1.0-1:i386
  libuuid1:i386 libwrap0:i386 linux-image-3.9.4-zgsrv2008064:i386 zlib1g:i386
0 upgraded, 0 newly installed, 70 to remove and 0 not upgraded.
After this operation, 67,5 MB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 17111 files and directories currently installed.)
Removing e2fslibs:i386 ...
( )
$ sudo apt-get remove $(dpkg --list   awk  if( $1 ==  ii  && $4 ==  i386  )   print $2
  )
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
70
$ dpkg --list   grep amd64   wc -l
175
$
To finally make the packages really vanish from the system, we purge all packages that dpkg --list still reports in state rc , which means removed, configuration still present . Thankfully, dpkg seems to handle the case where a dpkg-conffile belongs to a transitioned package gracefully. 
$ sudo dpkg --purge $(dpkg --list   awk  if ($1 ==  rc )   print $2  )
(Reading database ... 15868 files and directories currently installed.)
Removing e2fslibs:i386 ...
Purging configuration files for e2fslibs:i386 ...
( )
$ dpkg --print-architecture
amd64
$ dpkg --print-foreign-architectures
i386
$ dpkg --list   grep i386   wc -l
0
$ dpkg --list   grep amd64   wc -l
175
$
We now verify that all packages we have are either arch all or arch amd64. 
$ dpkg --list   grep -v  \(amd64 all\) 
Desired=Unknown/Install/Remove/Purge/Hold
  Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
 / Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
 / Name                            Version                   Architecture Description
+++-===============================-=========================-============-========================================================================
As I found myself suddenly without e2fsprogs during one of my experiments, I check for e2fsprogs being present. If this package is missing, you ll only find out after rebooting. 
$ dpkg --list e2fsprogs
Desired=Unknown/Install/Remove/Purge/Hold
  Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
 / Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
 / Name           Version      Architecture Description
+++-==============-============-============-=================================
ii  e2fsprogs      1.42.5-1.1   amd64        ext2/ext3/ext4 file system utilit
My locally built amd64 kernel with 32 bit support was an arch i386 package as well, so it got zapped in the migration process. Replace it with a real amd64 kernel. This step will vary if you use Debian kernels. Do not forget the firmwares. 
$ sudo apt-get -t wheezy-zg-experimental install kernel-image-zgserver linux-firmware-image
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  cpio initramfs-tools kernel-image-zgsrv20080 klibc-utils libklibc
  linux-image-3.9.4-zgsrv20080
Suggested packages:
  libarchive1
The following NEW packages will be installed:
  cpio initramfs-tools kernel-image-zgserver kernel-image-zgsrv20080
  klibc-utils libklibc linux-firmware-image linux-image-3.9.4-zgsrv20080
0 upgraded, 8 newly installed, 0 to remove and 0 not upgraded.
Need to get 11,2 MB of archives.
After this operation, 30,5 MB of additional disk space will be used.
Do you want to continue [Y/n]? 
Get:1 http://zg20110.debian.zugschlus.de/ wheezy-zg-experimental/main linux-image-3.9.4-zgsrv20080 amd64
3.9.4.20130605.0 [10,4 MB]
( )
I now make sure that the initrd I have built contains all file system modules and is of the right architecture: 
$ cd /tmp
$ < /boot/initrd.img-3.9.4-zgsrv20080 gunzip   cpio -i
32053 blocks
$ find . -name  *ext*.ko 
./lib/modules/3.9.4-zgsrv20080/kernel/fs/ext3/ext3.ko
./lib/modules/3.9.4-zgsrv20080/kernel/fs/ext2/ext2.ko
./lib/modules/3.9.4-zgsrv20080/kernel/fs/ext4/ext4.ko
$ file ./lib/modules/3.9.4-zgsrv20080/kernel/fs/ext4/ext4.ko
./lib/modules/3.9.4-zgsrv20080/kernel/fs/ext4/ext4.ko: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV),
BuildID[sha1]=0x259a642448805c9597932ee25c62c8e6a00a32ad, not stripped
$ cd
As the last step, remove i386 as an architecture and reboot into the newly migrated system. We verify that the system considers itself amd64 with no foreign architectures. 
$ sudo dpkg --remove-architecture i386
$ dpkg --print-architecture
amd64
$ 
$ dpkg --print-foreign-architectures
$ dpkg --list   grep i386   wc -l
0
$ dpkg --list   grep amd64   wc -l
181
$ sudo shutdown -r now
Broadcast message from root@wheezyarch (pts/0) (Wed Jun 12 16:09:24 2013):
The system is going down for reboot NOW!
$ Connection to wheezyarch.zugschlus.de closed by remote host.
Connection to wheezyarch.zugschlus.de closed.
$ ssh wheezyarch.zugschlus.de
Linux wheezyarch 3.9.4-zgsrv20080 #2 SMP PREEMPT Wed Jun 5 13:12:04 UTC 2013 x86_64
$ dpkg --print-architecture
amd64
$
We now check whether we have lost any packages in this process: 
$ sudo dpkg --get-selections   grep install   awk  print $1    sed  s/:.*//;s/$/:amd64
install/;  > get-selections.post
$ wc -l get-selections.*
  234 get-selections.post
  226 get-selections.pre
$ diff --unified=0 get-selections.pre get-selections.post 
--- get-selections.pre  2013-06-12 19:47:40.278176000 +0200
+++ get-selections.post 2013-06-12 20:28:51.389874000 +0200
@@ -22,0 +23 @@
+cpio:amd64 install
@@ -58,0 +60 @@
+initramfs-tools:amd64 install
@@ -68,0 +71,3 @@
+kernel-image-zgserver:amd64 install
+kernel-image-zgsrv20080:amd64 install
+klibc-utils:amd64 install
@@ -108,0 +114 @@
+libklibc:amd64 install
@@ -163,0 +170,2 @@
+linux-firmware-image:amd64 install
+linux-image-3.9.4-zgsrv20080:amd64 install
So we have not actually lost things, but we have gained the pure amd64 kernel and the packages that are needed to build a proper initrd. These were missing from the initial install of the i386 test VM. The downside of the process is that we have lost most of the automatically installed markers in aptitude which make sure to remove a library once nothing depends on it any more. If you make a point in having those markers correctly set, as I do, this is tedious work to set it on every package in the aptitude curses interface, making aptitude suggest removing the entire system, and then again remove it from the packages you actually intend to keep. This should not result in anything being removed, otherwise you have goofed previously. All Done! I am now off perfecting my upgrade process so that the i386 lenny and squeeze machines can first be moved to wheezy and then to amd64.

Petter Reinholdtsen: Debian Edu interview: Jonathan Carter

There is a certain cross-over between the Debian Edu / Skolelinux project and the Edubuntu project, and for example the LTSP packages in Debian are a joint effort between the projects. One person with a foot in both camps is Jonathan Carter, which I am now happy to present to you. Who are you, and how do you spend your days? I'm a South-African free software geek who lives in Cape Town. My days vary quite a bit since I'm involved in too many things. As I'm getting older I'm learning how to focus a bit more :) I'm also an Edubuntu contributor and I love when there are opportunities for the Edubuntu and Debian Edu projects to benefit from each other. How did you get in contact with the Skolelinux / Debian Edu project? I've been somewhat familiar with the project before, but I think my first direct exposure to the project was when I met Petter [Reinholdtsen] and Knut [Yrvin] at the Edubuntu summit in 2005 in London. They provided great feedback that helped the bootstrapping of Edubuntu. Back then Edubuntu (and even Ubuntu) was still very new and it was great getting input from people who have been around longer. I was also still very excitable and said yes to everything and to this day I have a big todo list backlog that I'm catching up with. I think over the years the relationship between Edubuntu and Debian-Edu has been gradually improving, although I think there's a lot that we could still improve on in terms of working together on packages. I'm sure we'll get there one day. What do you see as the advantages of Skolelinux / Debian Edu? Debian itself already has so many advantages. I could go on about it for pages, but in essence I love that it's a very honest project that puts its users first with no hidden agendas and also produces very high quality work. I think the advantage of Debian Edu is that it makes many common set-up tasks simpler so that administrators can get up and running with a lot less effort and frustration. At the same time I think it helps to standardise installations in schools so that it's easier for community members and commercial suppliers to support. What do you see as the disadvantages of Skolelinux / Debian Edu? I had to re-type this one a few times because I'm trying to separate "disadvantages" from "areas that need improvement" (which is what I originally rambled on about) The biggest disadvantage I can think of is lack of manpower. The project could do so much more if there were more good contributors. I think some of the problems are external too. Free software and free content in education is a no-brainer but it takes some time to catch on. When you've been working with the same proprietary eco-system for years and have gotten used to it, it can be hard to adjust to some concepts in the free software world. It would be nice if there were more Debian Edu consultants across the world. I'd love to be one myself but I'm already so over-committed that it's just not possible currently. I think the best short-term solution to that large-scale problem is for schools to be pro-active and share their experiences and grow their skills in-house. I'm often saddened to see how much money educational institutions spend on 3rd party solutions that they don't have access to after the service has ended and they could've gotten so much more value otherwise by being more self-sustainable and autonomous. Which free software do you use daily? My main laptop dual-boots between Debian and Windows 7. I was Windows free for years but started dual-booting again last year for some games which help me focus and relax (Starcraft II in particular). Gaming support on Linux is improving in leaps and bounds so I suppose I'll soon be able to regain that disk space :) Besides that I rely on Icedove, Chromium, Terminator, Byobu, irssi, git, Tomboy, KVM, VLC and LibreOffice. Recently I've been torn on which desktop environment I like and I'm taking some refuge in Xfce while I figure that out. I like tools that keep things simple. I enjoy Python and shell scripting. I went to an Arduino workshop recently and it was awesome seeing how easy and simple the IDE software was to get up and running in Debian compared to the users running Windows and OS X. I also use mc which some people frown upon slightly. I got used to using Norton Commander in the early 90's and it stuck (I think the people who sneer at it is just jealous that they don't know how to use it :p) Which strategy do you believe is the right one to use to get schools to use free software? I think trying to force it is unproductive. I also think that in many cases it's appropriate for schools to use non-free systems and I don't think that there's any particular moral or ethical problem with that. I do think though that free software can already solve so so many problems in educational institutions and it's just a shame not taking advantage of that. I also think that some curricula need serious review. For example, some areas of the world rely heavily on very specific versions of MS Office, teaching students to parrot menu items instead of learning the general concepts. I think that's very unproductive because firstly, MS Office's interface changes drastically every few years and on top of that it also locks in a generation to a product that might not be the best solution for them. To answer your question, I believe that the right strategy is to educate and inform, giving someone the information they require to make a decision that would work for them.

11 June 2013

Daniel Pocock: Interrupt-free computing

On debian-devel, there has been a discussion about the security issues of "spontaneously" appearing popups demanding the root password to make immediate security updates. There is a much more general issue related to this: computing without interruptions. Most of us have probably seen some friend or acquaintance with a (usually non-Linux) PC that is constantly beeping and flashing with chat notifications, new email popups, Adobe update this, Java update that, etc. In one recent case I came across somebody who had experienced a dramatic drop in his productivity as a consequence - giving him a laptop with a freshly installed copy of Linux made a dramatic difference to his work. I can already hear people insisting that security trumps everything (which isn't an original argument either) and that popups can't be avoided. A search on the web for "computing without interruptions" reveals users have a particular distaste for these things appearing while watching a video. Websites responding to that complaint fill the search results. With many types of interactive real-time content (video, WebRTC phone/video calls and so on) deployed within browsers, it is even more important for UI designers to contemplate when it is not appropriate to interrupt a user and to do everything possible to avoid interrupting the user. Preparing for disaster On the other hand, just ignoring security updates and not telling the user their disk is filling until 0 bytes remain available could only shift the problem down the road (from constant annoyance to periodic crisis). That said, sometimes you can still fill the disk very suddenly (especially with fast SSDs) and rather than relying on popups to keep users away from the precipice, applications (particularly the core desktop and daemon processes) could be tested more regularly to ensure they remain resilient in full disk situations. Managing information overload Popups are just part of a wider problem of information overload. There are emails too: some applications, such as Drupal, will send daily or weekly emails to a user if their system is not up to date. For many virtual-hosted sites, this starts to resemble a small flood. There is a flaw in this design: applications are competing for attention by sending more and more emails and popups or making them more annoying (e.g. the security updates in Debian 6 were ignorable popups in the top right-hand corner of the screen, Debian 7's Gnome Classic mode displays a big password prompt in the middle of the screen). The solution would be to develop a mechanism for unifying, de-duplicating and then prioritising these information/event flows. Some fault alerting systems already do this for their own events - these are niche solutions that aren't always applicable to the average PC-owner, although the principles are well tested. Some email organisation tools have similar features, but only for email. I'm not currently aware of any solution that synthesizes such an experience for all possible information sources. Setting priorities One well-read work on this subject in the business world is The 7 Habits of Highly Effective People (Stephen R. Covey, 1989). Of particular interest for the problem at hand is the priority matrix (borrowed from the Eisenhower Method): The left column, Urgent items, typically must be executed by a certain date (e.g. buying a gift before a birthday or installing a new SSL certificate before the old one expires). A security update or Acrobat reader update does not have this same characteristic. Under this model:
Urgent Non-urgent
Important Replace SSL certificate
Buy birthday gift		 Security update
Run backup job
Not important Register for conference before deadline for free gift Non-security update for Acrobat reader
Covey even released an Outlook plugin, Plan Plus to help people organise their tasks (and their lives) using his methodology. Unfortunately it is closed-source software with a terrible set of ratings on Amazon - this review from a customer stands out: "My take is that Franklin does not consider robust software nor customer support to be either Urgent or Important." Could this be replicated more successfully with an open-source plugin for Mozilla Lightning or a similar productivity tool, and could the concept be extended across the range of data sources, including email, calendar items, system notifications and more to provide a unified approach to both the computing platform and general productivity (real-life) time management? Would this help solve the same problem in a more effective manner? In other words, would such an effort to help users integrate the demands of technology with the other demands of life make them more likely to keep their systems up to date? The wider community experience Going beyond the desktop/user experience, could this model be extended to automatically integrate external tasks, such as handling bug reports, moderating mailing lists and other slightly tedious things that have to be given regular attention to keep the free-software world moving along smoothly? Managing down-time For people who work in computing, there is almost no down-time any more. Even when on holiday, checking in for a flight might involve navigating through a buggy wifi access control system and an annoying set of advertisements from your low-cost airline as you try to print a boarding pass. These things often trigger thoughts about similar issues on client projects. Glancing at your email to find the booking number could awaken thoughts of a whole lot of projects you had tried to put out of your mind for a week. This is another area where excessive popups and emails can only compound the problem. Who really wants to download and install security updates while on holiday using an intermittent wifi connection? Managing all these events through a common mechanism may also finally make it possible to have an "ordinary user" experience with your PC. In practice, this might mean being able to view information/events through a time-of-day filter or "holiday mode" - and only on demand. A worthy design goal? Would any free software operating system make it a design goal to give their users a 100% interrupt-free experience? Of course there would still be things like chat notifications - but those would only be possible when a user has signed-in to a chat application. The distinction for the interrupt-free experience would only need to apply to default system behavior and not to every application.

Ben Hutchings: Updating the Linux kernel for Debian 7.1

The first point release for Debian 'wheezy', 7.1, is due next weekend. The Linux kernel should be updated with: The new package, version 3.2.46-1, is available for most architectures in stable-proposed-updates. Please test it now if you can, so we can catch any serious regressions.

9 June 2013

Gregor Herrmann: RC bugs 2013/23

I know, I'm starting to repeat myself but: this week was again characterized more be RC bug prevention than by actual RC bug fixing. in other words: I was mostly dealing with not-yet release-critical bugs around the perl 5.18 transition. actual RC bugs I've worked on (also mostly pkg-perl related):

8 June 2013

Michael Stapelberg: Survey answers part 1: systemd has too many dependencies, or it is bloated, or it does too many things, or is too complex

This blog post is the first of a series of posts dealing with the results of the Debian systemd survey. I intend to give a presentation at DebConf 2013, too, so you could either read my posts, or watch the talk, or both :-). The top concern shared by most people is:
systemd has too many dependencies, or it is bloated, or it does too many things, or is too complex
Now this concern actually has a lot of different facets, and I am trying to share my opinion on each of them. systemd has too many dependencies First, let s start with too many dependencies , because that is easy to check and reason about. I have created a document which lists all dependencies of the systemd binary itself (pid 1) and all the binaries which are currently shipped by the systemd Debian package. If you don t want to take my word for granted, please read that document. Have you read the document? Very nice! As you can see, the systemd binary itself has 10 dependencies (excluding libc). Now, the question is, what is bad about dependencies? Why do people list dependencies as a top concern?
  1. Cyclic dependencies. When you hear that your init system depends on DBus, you might argue that there is a cyclic dependency here, because DBus needs to be started by the init system. However, systemd does NOT depend on dbus-daemon (!) to boot your machine. Instead of using the system bus, it uses a private UNIX socket. Therefore, systemd uses DBus merely as a serialization format for IPC between its different processes. Only when you want to access systemd via its API as a user (non-root), you actually use the system bus. Since we are talking about DBus: DBus provides a well-tested serialization format and IPC mechanism so that systemd doesn t have to reinvent the wheel and instead benefits from wide support within languages.
  2. Complicated code. I feel like there is the implicit assumption that lots of dependencies correlate with complicated code that is easy to break. I encourage you to have a look at systemd s source code: look for the places where specific libraries are used, e.g. enforce_user which uses libcap. You ll notice that the code is not complex and usage of the libraries is clear.
  3. Software dragging in lots of library packages. The libraries which systemd uses are already in widespread use (e.g. DBus, udev, selinux, libcap, pcre, ). On a typical Debian installation, only very few of them will be dragged in by systemd, if at all. As an example, on a fresh Debian Wheezy installation, less than 10 packages will end up on your machine when running apt-get install systemd .
  4. More memory use. The Linux kernel maps libraries into memory only once, no matter how many processes use them. As stated in the dependency list, on machines where the libraries are not already loaded, systemd brings in about 500 KiB of additional memory-mapped libraries in the worst case. On the machines we have these days, this is a reasonable cost to pay for all the benefits systemd gets us. This holds true on embedded systems with only a few MiB of RAM and especially on typical workstations with 8+ GiB of RAM.
systemd is bloated Now, let s talk about bloat. Again, this is a point which has many facets. I d like to quote the Wikipedia definition of software bloat:
Software bloat is a process whereby successive versions of a computer program become perceptibly slower, use more memory or processing power, or have higher hardware requirements than the previous version whilst making only dubious user-perceptible improvements.
The first part of the definition certainly does not match systemd it is measurably faster than sysvinit. As for memory usage: systemd s RSS is 1.8 MiB, whereas sysvinit uses 0.8 MiB. As I argued on the More memory use point in the dependencies section, I think the additional resource cost is well worth the benefits. Also note that systemd s features are NOT all implemented in the binary which is PID 1. As explained in the dependency list, systemd consists of many cleanly separated binaries. So if a new version of systemd gathers an additional feature, this does not mean that your PID 1 will be bigger. While systemd runs on any hardware, it has an indirect hardware requirement: it requires some Linux kernel features (which are all enabled in Debian kernels). That might rule out usage of systemd on really old embedded hardware where you don t have a chance to update the kernel. While it is sad that those machines cannot profit from systemd, switching to systemd as a default has no downside either: Debian continues to support sysvinit for quite some time, so these machines will continue to work even with upcoming Debian versions. systemd does too many things The Wikipedia definition continues:
[ ] perceived bloat can occur from the software servicing a large, diverse marketplace with many differing requirements. Most end users will feel they only need some limited subset of the available functions and will regard the others as unnecessary bloat, even if people with different requirements do use them.
I think the last part of the Wikipedia definition applies to systemd: it does service a large and diverse marketplace . That marketplace is the entirety of existing software which is started by an init system. Also, systemd can be used on a wide range of hardware (embedded devices, tablets, phones, notebooks, desktops, servers) which requires different features. As an example: on a desktop system you typically don t care strongly about a watchdog feature, but on embedded or servers that feature is very handy. Similarly, on a tablet, forward secure sealing of logfiles is not as important as on a server. Therefore, I can understand if you feel that you don t need many of the features systemd provides. But please think of other users and maintainers who are very happy with systemd s benefits. Also note that while systemd supports many things (in separate binaries!), you don t have to use them all. It still makes sense to ship them all in the same package. Take coreutils as another example in that area. The binaries belong together, even though you most likely haven t used all of them (e.g. od, pr, ptx, :-)). systemd is too complex The remaining concern is that systemd is too complex. In my experience, complexity is often inherent to a specific area and one cannot simply make it go away. Instead, there are different models of how that complexity is represented. Think of the monolithic Linux kernel versus the MINIX microkernel. The latter has a very small amount of lines of source in the kernel, but puts the complexity into userspace. The former uses a different approach with more source in the kernel. The arguments between both camps show that neither is clearly right or clearly wrong. In a way, sysvinit represents the MINIX model: it has a small core (the init binary itself), but a lot of complexity in shell scripts and external programs. The fact that solutions are copied from one init script to another leads to lots of subtle errors and makes code reuse really hard. systemd however has more source code in the binaries, but requires only very simple, descriptive, textual configuration instead of complex init scripts. To me, it seems preferable to have the complexity in a single place instead of distributed across lots of people and projects. Conclusion In a way, you are right. systemd centralizes complexity from tons of init scripts into a single place. However, it therefore makes it very easy for maintainers to write service files (equivalent of an init script) and provides a consistent and reliable interface for service management. Furthermore, it is different than sysvinit, and different solutions often seem complex at first. While systemd consumes more resources than sysvinit, it uses them to make more information available about services; its finer-grained service management requires more state-keeping, but in turn offers you more control over your services.

Daniel Pocock: Rendition link to PRISM

The Guardian is reporting that Britain's GCHQ first started getting produtive with PRISM early 2012. It was about the same time that their buddies down under, ASIO revised their earlier assessment of a refugee, Ranjini, and scooped her up in Australia's domestic rendition program. This may be more than a notable co-incidince, because it adds further support to the hypothesis that Ranjini is a victim of Big Data and PRISM. If ASIO first gained access to PRISM at the same time as GCHQ, then they may have used some tenuous PRISM data to form their revised assessment of her suitability for a visa. Making such inferences, and using them as the basis for a cruel program of indefinite detention is a gross violation of human rights and goes far beyond the claim that PRISM is about catching real terrorists. I've previously mentioned the systematic persecution of coloured people in my own country. Like many honest people, I'm utterly ashamed of it. The Government also has similar programs for indigineous people (they cooked one aboriginal elder alive on our national holiday) and they've also toyed with outlawing homosexuality. Having seen first hand some of the prejudiced, Government-sanctioned evil that exists in Australia, it's not hard to imagine small-minded members of the public service using PRISM data to target these classes of people for an unhealthy dose of bastardisation. Ranjini was ripped away from her husband by the rendition program and dumped in Sydney's Villawood death camp. Twenty-four hours after the gestapo got their hands on her, it was discovered she was pregnant - her child, an Australian citizen, was recently born and confined to the same concentration camp. Ranjini has racked up more than 12 months in captivity now, most of it while pregnant, and the Government has still not made any official charges against this woman. They say they can't comment on her case for fear of revealing their sources: once again, they don't want to talk about programs like PRISM that they share with the US. Maybe she just had one of the wrong people in her facebook friends list? That is not the sort of evidence that can be used to convict somebody in court, especially if the Government wants to avoid public questioning about their access to a close ally's secret database. Various rapists and murderers have made multiple court appearances in the last 12 months, tried and convicted in accordance with the procedures of justice. Ranjini has not been brought into a court room even once because the spooks don't want to reveal their sinister sources like PRISM.
Potential PRISM victim Ranjini Australia's close ties with the US Australia has had particularly close ties with the US for many years and just as the British GCHQ has been linked to PRISM, it seems Australia's ASIO is also in on the act. For those not familiar with the depth of this alliance, it is worth checking up on Pine Gap, the ECHELON program and the recent exposure (by Wikileaks) of one of our senators with unauthorised US spy connections - he quietly resigned for family reasons'. Pine Gap
Pine Gap, Australia This is not to say that the US is universally bad or that the strategic alliance is undesirable: rather, it is simply to demonstrate the strength of these links and the real risk that data-sharing is used for inappropriate purposes. While many of us in a technical field treat large volumes of data from a very theoretical perspective, it is worth remembering that in the wrong hands, data can be very dangerous and there are real human victims.

Steve Kemp: Migrations and movements

Recently I wanted to cleanup my "main" remote machine. It is a system I've had for many years, which started off as a i386 KVM-guest and was later migrated in place to an AMD64 installation. These days the host runs: The plan was originally to move the "mail stuff" to a new (wheezy) guest. I aborted that after discovering that the mutt-patched package has (IMHO) regressed. So today I spun up a new virtual machine, and configured it to host websites. Thus far I've migrated steve.org.uk, and lumail.org to the new host. Both simple sites that are built via my static-site-generator. Migration mostly involved configuring the proxy and the thttpd instances - then using rsync to migrate the content. I've renamed my current host, which was previously www.steve.org.uk and is now ssh.steve.org.uk, and pushed DNS changes. If all is smooth and happy I'll slowly migrate the rest of the sites. Fingers crossed this will be painless and I'll have a clean split between "login + mail" and "websites".

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