I am exploring on Embedded Linux for Mobile Development and Set top Box Application.
I need to do some R/D on Embedded Linux.
I found BusyBox is good for Set Top Box and Maemo for Mobile Development.
I wanted to know is there any Embedded Linux Distribution (open Source/free) which can be used for both Mobile Development and Set top Box Application.
I also wanted to know Other
Exclusively and widely used Embedded Linux For Mobile Development.
Exclusively and widely used Embedded Linux For Set Top Box.
thanks,
I'm not sure you understand the words you wrote. Set top box is a type of hardware, there are many of those being manufactured, each needs its own stack of software (at least the hardware porting layer, the drivers and the bootstrap). On top of the hardware-dependent stack you can put the BusyBox utilities or Maemo, or whatever else. An example of such hardware is Neuros OSD, with fully Open-Source software stack.
There's no one Linux distribution for embedded devices, as there's for PC's. Each device manufacturer tailors its own set of tools and drivers into the distribution they put on their devices. Most common examples are Android, BusyBox, etc., but it's not really a distribution in the sense you're used to in the PC world, because the actual kernel and drivers are hardware dependent and tailored.
Related
From my understanding, Qt and GTK on the Windows and OS X side are just wrappers around the native GUI libraries, like for OS X it wraps around Cocoa, and for Windows around Win32. However, my question is, how do they integrate with Linux? Do the Desktop Environment developers have to implement special libraries for either Qt or GTK or how does it work? I have looked around but I can't really find the answer.
A few further notes.
Neither GTK+ nor Qt use the native widgets of Windows and OS X. They approximate the look and feel using native APIs, but internally everything is all done custom.
GTK+ and Qt are responsible for, and define, the themes available to programs on Linux. Desktop environments typically provide a way to change the theme globally for all applications, but how this is done is defined by GTK+ and Qt. For example, GTK+ 3 typically uses ~/.config/gtk-3.0/settings.ini to store this information (and there is a programmatic API to this file).
Qt has a bridge for GTK+ 2 themes via QGtkStyle, and the KDE developers maintain versions of their Oxygen theme for GTK+ 2 and GTK+ 3. (The previous sentence may change in the future, especially now that GTK+ 2 is long dead.)
Update 1: Unix systems only provide a way to reserve a rectangular region of the screen to do what you want with it, including drawing (as in plotting a bitmap image) to it. Drawing (as in drawing shapes) is done by hand. GTK+ uses a library called cairo to do its drawing; I believe Qt wrote their own (QPainter?). Both Windows and OS X provide drawing APIs (Windows has several; OS X has Core Graphics). (X11 does have drawing primitives, but I assume they are not expressive enough to be used for modern 2D graphics; I wouldn't know...)
The same applies to font rendering, though modern Unix systems tend to base their font rendering on some generally accepted base libraries (freetype, fontconfig, fribidi, harfbuzz). GTK+ uses Pango to do text layout (actually arranging blocks of text into lines and paragraphs) and drawing (Pango integrates with cairo); I believe Qt also uses its own (this time I'm not sure).
I wrote about what X11 does do some time ago.
On Linux (desktops and laptops) the graphical screen is generally displayed (at least that was the case in beginning of 2015) by the X11 server. Your GUI app is communicating with that server thru sockets, often locally on a Unix socket like /tmp/.X11-unix/X0. The X11 server is generally Xorg.
For some embedded devices like Android mobile phones or some gadgets (GPS in cars, automotive or medical device industry) it is different (DirectFB, framebuffer devices -which is used by the X11 server on your desktop, ...)
Some distributions are switching to Wayland (or perhaps to Mir). Since I don't know these much, I cannot explain the gory details. AFAIU, there is still some server involved (which, like Xorg, is the only user-land software component talking to your graphics card) and some protocol, and major toolkits like Qt & GTK are been adapted to them (so if you code for Qt or for GTK, you don't care about those details, but you should upgrade your toolkit).
The graphical toolkits (Qt, Gtk) are interacting with the X11 server (or the Wayland one) thru some specific protocol(s), e.g. X Window System protocols for X11. For historical reasons, these protocols are quite complex, and practically require to follow some conventions like EWMH.
See also this answer to a related question. I explain there that X11 is not used today as it was in the previous century; in particular the server-side drawing abilities of X11 (e.g. Xlib's XDrawLine or XDrawText) are rarely used today, because the toolkit is drawing a pixmap image client side and sending it to the server.
Notice that you might consider giving not a GUI interface, but a Web interface, to your application (e.g. using libraries like libonion, Wt, ....); then your application becomes a specialized Web server, and the user would go thru his browser (in his desktop/laptop/tablet/phone) to interact with your app.
Practically speaking, user interfaces are so complex that you really should use some toolkit for them (Qt if coding in C++). Coding from scratch (even above Xlib or XCB for X11) would requires years of work.
There exist several other widget toolkits above X11, e.g. FOX toolkit, FLTK (but most of them have much less features than Qt or GTK).
There's no clear answer. There's no native GUI on Linux, as there is on Windows and OSX. X11, which is windowing system used on Linux (this applies to Wayland and Mir too), is very basic and low level and is responsible mainly for handling input devices and allocating windows to applications. It does not provide any GUI components such as buttons or text fields. In that sense, both Qt and GTK+ can be seen as "native" Linux GUI libraries. To make matters worse, desktop environment plays a part too. On Gnome, GTK+ can be seen as more "native", whereas on KDE QT is more "native".
Background
In our company we cooperate with manufacturer of machinery, we are developing C++/Qt crossplatform control applications for devices that they produce. In the past, we used to communicate with their devices through USB (virtual COM port). Now we were informed that this manufacturer plans to switch to LabVIEW (USB Data acquisition). Of cause we will receive relevant information in the future, nevertheless I would like to get some information about it and ask you question which i could not find on internet easily.
I am sorry for noob questions.
Questions
1) What is LabVIEW? Am I right that it is not a single piece of device, but bunch of hardware components, drivers and standards?
2) Who is LabVIEW developer? I have read How much time do I need to learn LabVIEW, but I am not sure. Is it a person who puts LabVIEW components together and makes firmware for them. Or a person who develops toplevel user applications that communicate with LabVIEW?
3) I assume that first part from Question2 would be done by our partner company. Second part will be upon us. But who creates communication protocol? Is there any standard way how DAQ communicates with its PC drivers, or is it upon programmer to develop communication protocol?
4) I have found there is driver for linux at National Instruments. Contains this driver some API/libraries that can be included in C++ code in a standard way and utilized to communicate with DAQ?
LabVIEW is a development environment for creating custom applications that interact with real-world data or signals in fields such as science and engineering. LabVIEW itself is a software development environment that contains numerous components:
G Programming: flowchart-like dataflow programming model
Hardware support: Support for thousands of hardware devices like scientific instruments, data acquisition devices, sensors, cameras, ...
Analysis and technical code libraries: Libraries for signal processing, communication, file I/O, control algorithms, ...
UI components and reporting tools: controls such as graphs, gauges, and tables to view your acquired data and tools to save data to file or databases, or automatically generate reports
Technology abstraction: Using technologies such as FPGAs, multicore CPUs, ...
Models of computation: When G is not appropriate simulation syntax, textual math, statecharts, component-level IP (CLIP) nodes, DLL calls, ... are available
LabVIEW is developed and maintained by National Instruments. It stands behind LabVIEW with comprehensive support, training, and certification options.
LabVIEW makes the process of integrating hardware much easier by using a consistent programming approach no matter what hardware you are using. LabVIEW has freely available drivers for thousands of NI and third-party hardware. In the rare case that a LabVIEW driver does not already exist, you have tools to create your own, reuse a DLL or other driver not related to LabVIEW, or use low-level communication mechanisms to operate hardware without a driver.
LabVIEW is also cross-platform and allows you to deploy your code to many different computing platforms like popular desktop OSs (Windows, Mac, and Linux), embedded real-time controllers, ARM microprocessors, and field-programmable gate arrays (FPGAs).
By the sounds of it you don't need to learn LabVIEW (which is a pity), but you need to learn daq-mx the hardware driver suite by National Instruments. I have no experience with the Linux version (which is a trimmed down or base version of the Windows one), but it basically is a set of dll's or so's that allow you to communicate with their hardware. Try to find out what hardware they are going to use and see if daq-mx base supports simulated devices.
Both Windows (Win32 API) and OS X (Cocoa) have their own APIs to handle windows, events and other OS stuff. I have never really got a clear answer as to what Linux’s equivalent is?
I have heard some people say GTK+, but GTK+ being cross platform. How can it be native?
In Linux the graphical user interface is not a part of the operating system. The graphical user interface found on most Linux desktops is provided by software called the X Window System, which defines a device independent way of dealing with screens, keyboards and pointer devices.
X Window defines a network protocol for communication, and any program that knows how to "speak" this protocol can use it. There is a C library called Xlib that makes it easier to use this protocol, so Xlib is kind of the native GUI API. Xlib is not the only way to access an X Window server; there is also XCB.
Toolkit libraries such as GTK+ (used by GNOME) and Qt (used by KDE), built on top of Xlib, are used because they are easier to program with. For example they give you a consistent look and feel across applications, make it easier to use drag-and-drop, provide components standard to a modern desktop environment, and so on.
How X draws on the screen internally depends on the implementation. X.org has a device independent part and a device dependent part. The former manages screen resources such as windows, while the latter communicates with the graphics card driver, usually a kernel module. The communication may happen over direct memory access or through system calls to the kernel. The driver translates the commands into a form that the hardware on the card understands.
As of 2013, a new window system called Wayland is starting to become usable, and many distributions have said they will at some point migrate to it, though there is still no clear schedule. This system is based on OpenGL/ES API, which means that in the future OpenGL will be the "native GUI API" in Linux. Work is being done to port GTK+ and QT to Wayland, so that current popular applications and desktop systems would need minimal changes. The applications that cannot be ported will be supported through an X11 server, much like OS X supports X11 apps through Xquartz. The GTK+ port is expected to be finished within a year, while Qt 5 already has complete Wayland support.
To further complicate matters, Ubuntu has announced they are developing a new system called Mir because of problems they perceive with Wayland. This window system is also based on the OpenGL/ES API.
Linux is a kernel, not a full operating system. There are different windowing systems and gui's that run on top of Linux to provide windowing. Typically X11 is the windowing system used by Linux distros.
Wayland is also worth mentioning as it is mostly referred as a "future X11 killer".
Also note that Android and some other mobile operating systems don't include X11 although they have a Linux kernel, so in that sense X11 is not native to all Linux systems.
Being cross-platform has nothing to do with being native. Cocoa has also been ported to other platforms via GNUStep but it is still native to OS X / macOS.
Strictly speaking, the API of Linux consists of its system calls. These are all of the kernel functions that can be called by a user-mode (non-kernel) program. This is a very low-level interface that allows programs to do things like open and read files. See http://en.wikipedia.org/wiki/System_call for a general introduction.
A real Linux system will also have an entire "stack" of other software running on it, in order to provide a graphical user interface and other features. Each element of this stack will offer its own API.
To aid in what has already been mentioned there is a very good overview of the Linux graphics stack at this blog: http://blog.mecheye.net/2012/06/the-linux-graphics-stack/
This explains X11/Wayland etc and how it all fits together. In addition to what has already been mentioned I think it's worth adding a bit about the following API's you can use for graphics in Linux:
Mesa - "Mesa is many things, but one of the major things it provides that it is most famous for is its OpenGL implementation. It is an open-source implementation of the OpenGL API."
Cairo - "cairo is a drawing library used either by applications like Firefox directly, or through libraries like GTK+, to draw vector shapes."
DRM (Direct Rendering Manager) - I understand this the least but its basically the kernel drivers that let you write graphics directly to framebuffer without going through X
I suppose the question is more like "What is linux's native GUI API".
In most cases X (aka X11) will be used for that: http://en.wikipedia.org/wiki/X_Window_System.
You can find the API documentation here
XWindows is probably the closest to what could be called 'native' :)
The linux kernel graphical operations are in /include/linux/fb.h as struct fb_ops. Eventually this is what add-ons like X11, Wayland, or DRM appear to reference. As these operations are only for video cards, not vector or raster hardcopy or tty oriented terminal devices, their usefulness as a GUI is limited; it's just not entirely true you need those add-ons to get graphical output if you don't mind using some assembler to bypass syscall as necessary.
Wayland
As you might hear, wayland is the featured choice of many distros these days, because of its protocol is simpler than the X.
Toolkits of wayland
Toolkits or gui libraries that wayland suggests are:
QT 5
GTK+
LSD
Clutter
EFL
The closest thing to Win32 in linux would be the libc, as you mention not only the UI but events and "other os stuff"
GUI is a high level abstraction of capability, so almost everything from XOrg server to OpenGL is ported cross-platform, including for Windows platform. But if by GUI API you mean *nix graphics API then you might be wandering around "Direct Rendering Infrastructure".
Are there any out there that are easy to get ahold of? Preferably free, as I don't have any money to spend right now.
What I'm trying to Accomplish
Basically, I'm writing a multi-platform application in native C/C++, and now that I have Linux installed, I feel as though I'm truly ready to make the "multi-platform" development go. Before anyone says "use SDL" or "Qt", note that I'm doing this for an application which I plan to go commercial with (Qt costs money for commercial applications). While SDL is good, I'm also looking to learn about window managers in general. I feel as though the best way to learn how to communicate directly with the operating system is to write the application yourself.
So, are there any resources out there?
First of all X-Windows has nothing to do with Linux.
X-Windows is both a graphical protocol and a GUI system built up around it. X runs on most OSes including Windows and Mac. The most typical scenario is for an X application to run on a multiuser computer running a UNIX-like OS (for instance Linux) and for the users to interact with it using an X-server which runs on either an X-terminal or a desktop OS. The X-Server is a standard piece of the X-System. If you install an X-Server on Windows then you will be able to interact with graphical applications running on one or more other computers.
It sounds like you want to focus on building the X applications, not the device drivers or the server or any other part of the X-system. Linux is as good a choice as any, but the books and documents that you need were likely written using Solaris or BSD UNIX. But it's the same API.
Since X has been widespread since at least the early 90's, look for books in secondhand shops and university jumble sales. Advertise on Craigslist for X related books.
The lowest level API for X is called Xlib. Toolkits like GTK and QT are layered on top of this so studying their code is a good way to learn how to do things. But there is also something called the X-Toolkit that runs over Xlib and used to be the foundation layer for GUI toolkits like Motif and others. If I were you I would start with X-Toolkit, to get familiar with all the component parts of X and how they interact. For instance, it will take you a while to get used to the fact that a window manager which manages the windows on an X-Server display, doesn't run on the X-server but runs on a remote system. Or that you can have apps running on Linux and OS/X and Solaris all displaying their windows on the X-server on a single Windows box.
Google X Toolkit intrinsics to get all kinds of info including free reference manuals.
As you read more about it you will come across a lot of other unique terms that you can google to get additional info and a broader perspective. Don't spend too much time with old toolkits like Athena Widgets or Motif.
Since there were more people programming X in the early days of the Internet than today, the USENET FAQs are still a good source of introductory tips, e.g. http://www.faqs.org/faqs/Xt-FAQ/
You can write your app as a server in C. Call it Engine. No need to think about the User Interface. After that you can create interface in Qt. The communication protocol will be public (or private) and your Qt application will be open-source. Later if you like you can create many more interface to your application. Such as web interface, Gnome interface, C#.NET interface etc.
I want to know what operating system NOKIA smart-phones use? Which programming language is used to write it and is it possible to do kernel level programming for these systems? Can we use C codes to change the system software? Libraries are available or not? I have never coded for mobile phones. So if possible give me a link to the pages where these topics are discussed in detail. Thanks in advance.
EDIT: I want the details for NOKIA s60 v3 and v5.
From http://en.wikipedia.org/wiki/Nokia_S60:
The S60 Platform (formerly Series 60 User Interface) is a software platform for
mobile phones that runs on Symbian OS.
The S60 software is a multivendor standard for smartphones that supports
application development in Java MIDP, C++, Python and Adobe Flash.
Note that you'll have to register as a developer or jailbreak the phone:
(S60v3) uses a hardened version of Symbian OS (v9.1), which has mandatory
code signing. In S60v3, a user may install only programs that have a
certificate from a registered developer, unless the user disables that
feature or modify the phone's firmware through third-party hacks that
circumvent the mandatory signing restrictions.
Nokia has Symbian kernel (i don't know about them much) and LINUX kernel like the one in N900 (using maemo and meego) though N900 is considered as a tablet-pc more than a smartphone and it has lots of modified kernels .