Yocto: mature or not?

This is a bit of fun spoiling post, but sometimes we need to become constructively critical in order to improve the situation. As you may already know, Yocto has been advertised as the relatively new technology for creating custom distributions for you. Although, people commonly use Poky, Arago, and so forth ready-made distributions on top of Open Embedded.

Yocto Project

Cross-compilation

So, here is the critical issue for embedded developers using the cross-toolchain provided by Code Sourcery why I personally think that Yocto might not be usable for the moment for commercial projects where reliability is a main concern.

In short: it does not work if you would like to build the distribution (for instance stock Poky) for your embedded board, like ARM with the sourcery toolchain.

What makes me worry a bit more, this cross-toolchain environment was working in the first half of 2012 yielding some regression in here. That opens up new concerns about QA, right? It is fundamentally broken and can be reproduced easily as acknowledged in the bug report above, yet the changes got in.

One could suggest to revert back to the very old and unsupported version. Well, it is unsupported first of all, so you cannot reliable base a commercial product on top of it. More importantly, that version has a lot more issues. I have tried to back port fixes to that release from master, but I have not had so much fun. I experienced many merge conflicts and so forth.

Cross compilation

Unsupported Archlinux

It is a bit disappointing that such a common distribution as Arch is not supported. Please do not write me that they do not enough manpower. I fully understand and appreciate that. Yet, it means Archlinux developers are in trouble.

Archlinux

Unsupported releases

They, kinda, support two releases back. They have a time based release cycle. One new release comes in every half a year. This brings us to the point that they only support your selected software version up to maximum one year. That is not so comfortable when you need a reliable product. I just faced the issue yesterday that there are fixes in old release branches, but no one has cared to release them for more than half a year. They will probably not be released either. I am now referring to the denzil version coming from April in 2012. So, it is not quite like the Linux kernel or Ubuntu LTS.

Long Term Support (LTS)

Error reporting

I think this is also a hard sell in Yocto as of now. There are issues that I could not simply figure out on my own as a newcomer without quite a bit of time with analyzing, especially when the public documentation is not up to the task either. There are several issues which made me spend a few days just to understand them, and that what is going on underneath.

The first bogus error reporting is about bblayers.conf file mismatch based on the generated file and the sample available. It was even hard for others to provide some help on IRC who have been experienced with the project. Here you can read the details about it.

Then, there is the issue of mismatching cross-compilation toolchain and MACHINE configuration. In my case, I would like to use the arm gnueabi toolchain from gcc for my omap board, particularly for the arm core. All fine, the external sourcery toolchain is setup, but the default config file generated for the build comes with "qemux86". When you try to generate the distribution, you will get weird toolchain issues about x86. I have been surprised because I explicitly specified the toolchain what to build with. Having spent 1-2 days with trying to understand the situation, it boils down to that the default MACHINE config generated, screwed this up. It would have been so much easier if it is reported up front with a warning that the toolchain and machine configurations are mismatching. Here you can find the bugreport about that one.

There are more to it, albeit the last, but not least I would like to mention here is the one when you get tab/space issues when migrating from an older poky version, or you just get those for some reason. Reporting those issues should be easy, shouldn't it? Theoretically yes, but in practice, all you will get a file having issues tab and space issues. I did not quite get the point what the issue is after checking the offending file for quite a while. It turned out that the real problem is in the include file which it was requiring. Again, a newbie would spend a lot of time with it without external and professional support. I would even go further than reporting the right file as in: it would be nice to get a report for the location as close as possible. That is, a function name, perhaps a list of offending line numbers, and so forth. Here you can find the relevant bugreport for this.

Please note that, I have been told for some of these that it is not an easy fix as the parser design is not prepared for such use cases. It unfortunately means, it is not just about adding a minor feature, but basically revamping the parser.

Error messages

Documentation

There are some issues here as well I hit. I had a DISTRO_FEATURE entry "--disable-zlib" that I inherited. I was looking into it, but I have not seen anything like that in the reference manual. I guessed respestively that, it is not a proper syntax, so I can remove it. Right, you would imagine it could be as simply as that?

The problem is that, yes, theoretically, but in practice: I have seen other undocumented DISTRO_FEATURES like "opengl". I opened up a bugreport for that, but the problem is that, once you find a feature not documented, how will you know what to do with another not represented. Is that a mistake, undocumented, or what exactly? :)

I would not like to bore the reader, so I will only give one more example in here. I have been told that external toolchains should work, yet, it is not documented in the released documentation properly. Even in the development version of the next generation documentation, it is a bit of sloppy. You get the documentation of 2-3 variables, but you do not have any concrete example at hand. Then, I have been told to use the meta-toolchain/sourcery layer. As for the latter, I do not even find any documentation that could be useful for me on github from Mentor Graphics. I created a bugreport for that one, too.

Dr. Documentation

Conclusion

I am objectively pessimistic with the current state as an Arch user who is looking for a reliable product in an embedded environment with cross-compilation. I have spent a couple of days to experiment with all this, and I just wanted to let you the limitations so that you do not need to go through the same issues. Oh, and please do not write that "It works for me" because yes, I heard people using git master or not even that with supported distributions, and very simple setups where cross-toolchain is not necessary, et cetera. I am now referring to Arch, embedded, and so forth scenarios. I of course appreciate the Yocto people's work a lot, and I hope they can put more effort into this project to address those issues in the, hopefully near, future.

Conclusion

aKademy mola (i.e. rocks)

Back in the UK!

While having a short discussion with David Edmundson at the Stansted airport in London, we realized that this has been one of the best annual KDE summits we attended to. We made a note that the organization team always kept us busy with awesome social programs.

One of those funny pictures

I think Milian summarizes it in his blog post well: "The reason why I didn’t write a single blog post in between is just that I never had a spare minute for that. "

Many thanks go to the sponsors, organizers and participants who made this vacation in Spain an unforgettable success. ;-)

Photos, blog posts and other information can be found on the official web page.

C++ and built-in range support for switch cases?

Worth adding? Details here: https://groups.google.com/a/isocpp.org/forum/#!topic/std-proposals/HZZ_t8abzU4

C++ and compile-time guaranteed pointer safety?

Personally, I would find this feature useful, but I am not a C++ expert by any means. ;-)

Do you think this would be a useful feature to add to the TR, and then later the standard after C++14? Let me know if you have any alternative suggestions within the currently available or already planned feature set to address this issue.

Oh, and if you do not know what this all means, here you can find the explanation of a good reference design: http://static.rust-lang.org/doc/tutorial.html#borrowed-pointers

C++ and header files

Just got into a conversation with my dear room mate, Ivan, here in Bilbao at aKademy about this.

My personal opinion seems to have leaned towards preferring to not have to write them myself. Rather, I am happy to have them generated by a util, for instance during the build process.

A real life example could be rustdoc, most probably. I also realize that it is a bit of an unrealistic wish at the moment, but as I am on vacation now I am entitled to dream a lot. ;-)

Mobile hotspot connection on Linux

Hi,

I always wanted to write a short blog post about connecting to a mobile hotspot like joikuspot on my N9 phone. The application uses ad-hoc mode, but it can be easily adapted to managed mode like on the Blackberry DevAlpha, Z10 and Q10 devices. Just replace the "ad-hoc" mode with "managed". Unfortunately, joikuspot does not support wpa and wpa2, so this command will be primarily useful for wep. If you leave the key option out, it is also useful for open (i.e. brief sanity checks, et cetera).

Here you can find a reference command which works fine across distributions and even without GUI:

iwconfig wlan0 mode ad-hoc essid Test key s:TestTestTests && dhclient wlan0

It is admittedly not a big thing. However, I lost this command several times in the past. Now, I would know what to do by heart, but what about this in half a year or later? :)

Also, netcfg and similar distribution specific utils kept being broken for some reason. This was always the fallback for me which worked off-hand. Hope it helps. :-)

QtSerialPort in Qt 5.1

Hi everyone,

I would like to introduce you to a project I have been working on lately under the Qt Project umbrella. Hope, you find it useful. :)

History

 

The serial port technology is quite old, but still in active use today. It is mostly used for communicating with modems, sending control commands and so forth where the universal serial bus is not necessary. I am sure many of you recall the time when soldering the pins and cable manually to get it right for the embedded boards. :-)

About a year ago, I was looking for a library for my project to handle the serial port communication with the modems I needed. As I had been about to make a touch friendly UI with QML, I thought it would have been nice to have a Qt solution. It would have been phantastic to communicate with the modem on my Windows, or Linux host.

There has been an old library around for a while, called QExtSerialPort. Unfortunately, its API looked weird and the project had been abandoned for a while without people contributing to it. Then, a chinese person began to fix certain issues, but still: the design had been carried for long from the old ages.

Serial Port Cable

Qt Project Playground

The Qt Project established a nice opportunity for contributors to start a new project, or move an existing to the Playground area. There was a discussion on the development mailing list to figure out the rules for handling this. Around the time, when I requested the QtAudio3D project into the Playground area of the Qt Project, there was a russian person, Denis, who initiated a community project into Playground in his own pastime to make a great developer experience for serial port based projects across platforms.

The library was supporting only Qt5 back then, and my project was based on Qt4. This is understandable as Qt5 was not realeased for the time, so we were unable to take the risks of the moving target. I decided to give the project a go and make support for Qt4. Not much later (i.e. 1-2 weeks), I got the first changes into the Qt Project, following the Gerrit workflow. By that time, it was more or less possible to use QtSerialPort with Qt4.

Gerrit - Code Review Tool

Our work has been achieved by using the Qt instance of the awesome Gerrit codereview tool. Almost every commit got at least one review, but many times two, or sometimes even more. I think that is nice, and helped to guarantee the quality of the work even without having a Continous Integration (CI) in place for the time.


As time time had flied, I had more and more feature requests and own changes for those to implement. That is how the library kept rolling, getting new features and bugfixes. The API was also a bit too low-level, and I began to send patchs to refactor the API to be more Qt style'ish. As I am a geek, I instantly wrote a command line based example to enumerate the devices. It was necessary for me to get the project tested on my pandaboard where the UI was not available. There were also important features added like support for gadget serial driver on Linux and so forth.

The command line enumerator example

The initial plan was to make QtSerialPort available as an add-on module for Qt 5.0. This had been proposed on the development mailing list last year. You can read the platforms and environment supported in that threa. Unfortunately, the Qt Project did not have enough capacity for this integration. Likely, it was also good for us because we were able to clean up the remaining uncertain bits of the API. I am not claiming it is now perfect, but it looks much better than it used to be. :-)

Future plans

 

As you can read in the topic of this post, QtSerialPort makes it for Qt 5.1. This has been approved by Lars, the Qt Project Chief Maintainer, in the aforementioned thread. This is a really great and exciting news for us. It is also a very good prove for the Qt Project that the idea actually works. Community people can contribute with new modules under the same umbrella with the companies behind the Qt Project.

The main short term plan is to get the integration right in terms of Jira and Gerrit to move out of the Playground scope. As the CI integration has happened lately, the project is now also covered for build tests, so we cannot end up in situations like having regressions as before. It is not so simple to maintain such a project like this without proper CI integration because we experienced many regressions on one platform when we tried to fix issues or add new features.

FTDI USB-Serial adapter

As you may already know, it is not simple to test the serial port projects automatically. There had been an initiation for a Qt Mock project from me last April, but it did not yet manage to reach any progress. Nevertheless, we are working on making tests available as much as possible.

My personal plan is to write a KDE frontend for the library, preferrably also a terminal emulator. We already have a terminal emulator example in place to represent the developer and user experience for the project. It is not full-fledged, but it has been working nice for the basic needs. You can set the baudrate, parity and stop bits, flow control et cetera. Something like that would be nice in the KDE project, or perhaps even a plasmoid. There has been a CuteCom around for a while, but when I briefly discussed the project with Alexander Neundorf last summer at aKademy in Tallin, it did not support all the platforms we need.

Terminal example

As you may already know, the QNX platform is also getting closer to a Tier 1 stage in the Qt Project. Blackberry, formerly known as Research In Motion, and KDAB made an excellent job in that area. I have been considering to add a QNX backend support for the project at some point.

Kudos

 

First of all, many thanks to the Qt Project!

Secondly, many thanks to all the contributors to QtSerialPort!

Authors

The reviewer statistic is generated by the following command: git log --grep '^ *Reviewed-by:' | sed -n 's/^ *Reviewed-by: *//p' |  sed 's/ *<.*>//' | sort | uniq -c -i | sort -n -r

Reviewers