I am New to VxWorks. First of all Can I use VxWorks OS as Normal OS on my PC? I mean Can I run my application software on VxWorks OS?
While VxWorks can run on PC hardware, it is not a general-purpose OS for running independent executables. VxWorks is an RTOS library; you statically link it to your application and the whole runs as a monolithic executable.
It does support a command line interface (intended primarily for development and debug), and from that it is possible to dynamically load and link object files, but these are not independent executables in the sense they are in a GPOS; they essentially become part of the monolithic application.
An RTOS such as OS/9 or QNX would be more suited as these can operate more like a GPOS in the sense of loading and executing independently linked executables.
In any event, application software must be specifically built for these targets.
For versions of VxWorks prior to VxWorks 6, the answer by clifford provides a good explanation of why this is not really possible.
VxWorks 6 introduced Real Time Processes (RTPs). These are independant, user mode applications, running on top of the VxWorks OS. Dependant on how the VxWorks OS has been configured and built, these RTP applications may have access to POSIX libraries, and so you may be able to run POSIX applications (eg linux programs) with little modification.
However, these must still be built for VxWorks, ideally linked against your own VxWorks Source Build.
You cannot, however, just pick up any old application and expect it to run. You are never going to get Word or Excel to run.
Related
I've heard that Smalltalk is also an OS.
How can I install Smalltalk on my X86 instead of Linux or windows?
What are the steps to do that?
Any tutorials on installing Smalltalk on a bare-metal machine ?
I don't know if there is a standalone smalltalk environment, but you can try squeak, which runs above your os (linux, windows or mac). Not just an os but a complete working environment.
There was a project called SqueakNOS. That was the only post-PARC experiment to use Smalltalk directly loaded over the hardware, with no other operating system. It had even a version to work on an OLPC.
I don't know if currently someone follows that development, but it's very interesting and an excellent place to learn about hardware, in human-readable (but executable) terms. You can see and debug how a device driver works, for instance.
Smalltalk Virtual Machine is handling memory allocation, access to file systems, network connections, process (green thread)...
So viewed from Smalltalk world, it is very similar to an OS.
But how to implement the virtual machine without an underlying OS?
There is a project SqueakNOS and a fork PharoNOS meaning No Operating System, whose goal is to completely bypass the OS, and have Squeak/Pharo running on bare hardware.
So yes, it's possible.
But what you'll get with this is still a Smalltalk world, maybe not what you expect from a linux or windows distribution...
The questions I would like to ask are:
1) What exactly does hypervisor do? Why is it needed?
2) What is the difference between hypervisor and Java Virtual mMchine?
3) Does JVM use a hypervisor?
4) When a host operating system like linux can handle multiple guest operating system,why use hypervisor?
Would be great help if someone shed light on this
A Hypervisor also known as hardware virtualization are a virtualization layer that allows running one or more native operating system on top of it, as if they run on a physical machine. It is similar to emulation but only runs operating systems that would be able to run without the Hyperviser, which are much faster.
Both are virtualization layers. However Java are optimized for performance and portability. While Java are technicaly an emulator, it are much faster than an hyperviser. This can be achieved because the emulated platform are designed for fast emulation. Java do not run x86 or x86_64/amd64 code, it runs something called Bytecode. The technical term for Bytecode are Intermediate Language (IL). It are compiled to code that are native to your processor when you run it, by the Just In Time compiler (JIT). As the JIT do a compilation process it can make sure that the program follows Java:s security constraints, by simply not generating code that violates such constraints. The Hyperviser enforce security constraints by intercepting so called privileged instructions and by emulating devices such as disk drives. This are done because native x86 or x86_64/amd64 code are very hard for a program to understand, and changing it so that it self-enforce security constraints are next to impossible. Java on the other hand runs Bytecode which are easy for a program to understand and chance so that it self-enforce security rules.
The short answer: An hyperviser are slower than Java but allows you to run a multitude of complete operating systems, and all the software available for them. This while Java are faster, but you can only run Java software on it. If you want to run Windows and Office in your virtual machine, you can't do that in Java.
I think I answered this above but no, it use code inspection and modifies the program so that it self-enforce security rules. This can be done because runnable Java application are in a intermediate state called Bytecode, which are easy for Java to understand, inspect, find code that may violate the rules and modify it in order to obey them. This are a rather complex process that have several advantage over hypervisor. The first advantage are "compile once run everywhere", as Java are compiled and distributed as bytecode. The second advantage are speed, JIT:ed code have the same speed as non-virtualized code even when strict security are enforced. The disadvantage are that only Bytecode programs can run, so you for example cannot run Windows or Linux inside the virtual machine.
If you are running another operating system like Windows or another Linux distribution - you are running an Hyperviser. KVM, Xen and VirtualBox are examples of Hypervisors. You can also run multiple instances of Linux with one shared kernel, known as OS-based virtualization or "Container". But a Container share the kernel and therefor you can only virtual machines with the OS you are running. The advantage with Containers it are more lightweight as you do not need to run multiple kernels on top of each other...
Hypervisor or virtual machine manager, is a program that allows multiple operating systems to share a single hardware host.
JVM or Java Virtual Machine interprets bytecode for a computers processor so that it can perform Java program instructions.
No JVM does not use hypervisor as it is not an virtual machine that runs an OS rather it is just a interpreter.
A host operating system manages different VMs using Hypervisor or virtual machine manager
Before answering your questions, I would recommend you search related entries in wikipedia. A hypervisor is used to run multiple guest OSes while JVM is used to interpret java byte code. JVM runs on top of OS and it doesn't care whether the OS runs on top of bare metal or on a hypervisor. Actually, linux can handle multiple guest operating systems with KVM which is part of the linux kernel. So the description of the last question is totally wrong.
I just want know why some games are only Windows-based and won't run on other OSs like Mac OS X and Linux. What makes them different, and how does the program know that the OS is Windows, Linux, or Mac?
Also, similarly, why won't a Windows 7 32-bit driver work on 64-bit and vice versa?
Besides how Mac and Linux use a different executable type (they use Mach-O and ELF, as far as I've seen) than Windows (PE), if the executable loader was able to parse everything and load it into memory, many things can go wrong. Library calls, such as printf(3) rely on underlying system calls, which calls the kernel of the OS. In the case of printf(3), it calls fstat(2), sbrk(2) and write(2). (Note that this is the case under the newlib library; I am unsure about the other standard C libraries.) As far as you know, the system call interface for Windows can be very different from the one Linux uses, and Windows may even be missing a few system calls that Linux has (like fork(2))
I am an ASP.NET developer, but now I want to build a software that can be installed on my PC. Software built in .NET platform only works when the .NET Framework is installed, and software written in Java only works if the JDK is installed. When I install programs like Firefox, uTorrent, etc., I don't need to have any frameworks (.NET, JDK, etc.) installed. How do I write software that doesn't depend on a framework?
You will have to use a language that isn't dependent on a framework or otherwise only target clients that are already have your framework installed.
If you chose C or C++ for example, you would distribute binaries to your client that contained machine code. This code would not be dependent on a runtime environment (like C# or Java) or an interpreter (like Python or Ruby). This is the way that applications like Firefox and uTorrent are written.
"When I install programs like Firefox, uTorrent, etc., I don't need to have any frameworks."
Actually, you do. They just tend to use the C++ frameworks, such as MFC, some of which are already installed. Even then, there are installers for these frameworks that are included with other application installers (usually called Microsoft Visual C++ 2008 SP1 Redistributable Package or something like that. See Also: Visual C++ Deployment).
Now, having said that, they don't require a virtual machine (like a JVM for Java or a CLR for .NET), because C++ compiles down to x86 / x86-64 machine language to be executed directly by the operating system.
Fundamentally you always have a "platform", which is the operating system. Traditionally if you want to write code that will run on multiple operating systems you would use a fairly portable language such as C++ that produces native executables for a target operating system. Still, there are differences between how different operating systems work. There will therefore be parts of the C++ (or other portable language) code that are specific to that OS. You try to isolate those parts as much as possible to minimize the effort to port between OSes. Still, that effort is typically very substantial. You are also limited to the least common denominator of features available on all target operating systems (unless you create a custom version for a given OS that exposes its special features).
This is complex, time consuming and expensive. That's the reason technologies such as Java and .NET were created.
If You want to build really platform independent software You will finally end up with solution like Java Runtime or .NET. What You could do, You could thing about writing application in such way that You are able to compile/run it on most known platform, and of course then You need middleware to translate Your application's objects into platform objects (functions, whatever...).
I have seen solutions made in Pascal for DOS in such layer of abstraction that with little effort it was moved directly to Delphi for Windows without touching application logic.
Does anyone know of a good software development framework or similar that has the following properties?
Cross platform: it should be runnable on XP, Vista, OSX and common versions of Linux (such as Ubuntu and Kubuntu).
No installation: Be able to run the software from a USB stick without having to copy anything to the host machine.
Have good GUI support (this is why this question doesn't give a suitable answer, as far as I can tell).
Permissive licensing such as LGPL or BSD or such.
Among the softer requirements are having a set of abstractions for the most common backend functionality, such as sockets, file IO, and so on (There is usually some platform specific adaptations necessary), and supporting a good language such as Python or C++, though it is usually fun to learn a new one (i.e. not perl).
I think possible candidates are Qt 4.5 or above (but IFAIK Qt software will not run on Vista without any installation(?)), some wxWidgets or maybe wxPython solution, perhaps gtkmm. The examples I have found have failed on one or another of the requirements. This does not mean that no such examples exist, it just means that I have not found any. So I was wondering if anyone out there know of any existing solutions to this?
Some clarifications;
By "framework" I mean something like Qt or gtkmm or python with a widget package.
This is about being able to run the finished product on multiple platforms, from a stick, without installation, it is not about having a portable development environment.
It is not a boot stick.
It is ok to have to build the software specifically for the different targets, if necessary.
The use case I am seeing is that you have some software that you rely on (such as project planning, administration of information, analysis tools or similar) that:
does not rely on having an internet connection being available.
is run on different host machines where it is not really ok to install anything.
is moved by a user via a physical medium (such as a USB stick).
is run on different operating systems, such as Windows, Vista, Ubuntu, OSX.
works on the same data on these different hosts (the data can be stored on the host or on the stick).
is not really restricted in how big the bundled framework is (unless it is several gigabytes, which is not really realistic).
It is also ok to have parallel installations on the stick as long as the software behaves the same and can work on the same data when run on the different targets.
A different view on the use case would be that I have five newly installed machines with Vista, XP, OSX, Ubuntu and Kubuntu respectively in front of me. I would like to, without having to install anything new on the machines, be able to run the same software from a single USB stick (meeting the above GUI requirements and so on) on each of these five machines (though, if necessary from different bundles on the stick).
Is this possible?
Edit:
I have experimented a little with a Qt app that uses some widgets and a sqlite database. It was easy to get it to work on an ubuntu dist and on osx. For windows xp and vista I had to copy QtCored4.dll, QtGuid4.dll, QtSqld4.dll and mingwm10.dll to distribution directory (this was debug code) and I copied the qsqlited4.dll to a folder named "sqldrivers" in the distribution directory.
You mention wxWidgets but dismiss it as failing at least one of the requirements.
I don't know what your requirements are and in what way wxWidgets wouldn't work for you, but IMO it does fulfill them:
Cross platform: it should be runnable on XP, Vista, OSX and common versions of Linux.
It does run on those platforms, but "common versions of Linux" isn't good enough, as you can never be sure that the necessary GUI libraries for wxGTK (which should not be linked to statically) will be installed. This is however a problem for other solutions as well, unless you plan to put everything onto the stick.
No installation: Be able to run the software from a USB stick without having to copy anything to the host machine.
See the previous point, you would need to specify which libraries are needed on Linux. Also you could specify at build time not to use some of the system-provided libraries (for example for graphics, compression, regexes) but to use the wxWidgets-internal libraries instead.
Have good GUI support
Check.
Permissive licensing such as LGPL or BSD or such.
Check. You can statically link wxWidgets into your application too.
supporting a good language such as Python or C++
Supports both, and there are bindings to other languages as well.
having a set of abstractions for the most common backend functionality, such as sockets, file IO, and so on
It does have some abstractions like that, but you can link to other cross-platform libraries as well.
We use wxWidgets for FlameRobin, a graphical administration program for the Firebird SQL server. It has active ports to Windows, Linux and Mac OS X, and has been compiled for at least some BSD variant and Solaris as well. It definitely runs from a stick on Windows, I haven't tried with Linux or Mac OS X, but I don't see why it shouldn't there too.
Java.
It has GUI support.
It provides your network/file/etc. abstractions.
It is cross-platform. Most platforms you can think of have a JRE available.
No need to install a JRE. Most users probably already have one, and if not, you can run the appropriate JRE right off the stick.
You can provide several startup scripts for various platforms to run the app under the appropriate JRE.
Something else to consider is HTML+Javascript. :D
You can look at Mono it cross platform, has GUI (GTK+, or Winforms 2.0) and I can execute code without installing.
This might not be crossplatform, but is maybe even better, it dont even use the platform : linux on a stick :-)
The subtitle is
Take your Java workspaces wherever you go on a USB key
Here with java and eclipse, but nothing stops you there of course.
http://knol.google.com/k/inderjeet-singh/installing-a-ubuntu-hardy-heron-java/1j9pj7d01g86i/2#
Well, it depends on what you mean by 'package'. Kylix came close to being such a thing. It was QT based, and it allowed you to write once and compile for Windows + Linux. However, it was not an open source solution.
I asked a similar question in this link
http://www.24hsoftware.com/DevelopersForum/CrossPlatform-C-Library.html
and the best asnswer seems to be QT.
I have started using QT, but it is not as easy as I expected mainly due to deployment problems due to the DLL hell, Winsxs hell and manifest hell.
Tclkit is a single-file, self-contained Tcl/Tk system. The mac version I have is about 3.8 megs. You can get a version for just about any modern OS. I carry around a thumb drive that has mac, windows and linux binaries so I can run my scripts on any platform. No install is required, just copy one file wherever you want.
The most recent versions of tcklit use native, themed widgets (though, on *nix there really isn't a single "native" set of widgets...)