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I like operating systems and would eventually like to become a OS developer mostly working on kernels. In the future will C still be the language of choice and what else should I be trying to learn?
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Mac computers are also powered by C, since the OS X kernel is written mostly in C. Every program and driver in a Mac, as in Windows and Linux computers, is running on a C-powered kernel.
that's because nearly every c++ app needs a separate c++ standard library to operate. so they would have to port it to kernel, and expect an extra overhead everywhere. c++ is more complex language and that means that compiler creates more complex code from it.
Most of the operating systems are written in the C/C++ languages. These not only include Windows or Linux (the Linux kernel is almost entirely written in C), but also Google Chrome OS, RIM Blackberry OS 4.
Among the research crowd, there is a lot of of interest in using language-based technology to guarantee that the kernel can't misbehave. A number of people have mentioned the Singularity project, which currently has a (deservedly) high profile. Why is Singularity interesting?
The language includes a finite-state model for the proper use of locks. The compiler can model-check the code against the model to be sure that deadlock doesn't happen.
Third-party drivers are given a limited interface to the system. The checking done by the compiler guarantees that a bad driver cannot take out the system---the worst it can do is knock out its own device.
Singularity uses compiler technology, not OS/MMU technology, to isolate one "process" from another. Suddenly forking a new "process" (really a new kind of protection domain) is dirt cheap, and this cheapness enables new designs.
Singularity is just the latest in a long list of projects that have used language and compiler technology to solve OS problems. One of my favorites was the University of Washington SPIN kernel, which allowed applications to extend the kernel safely and was written in Modula-3.
This area of research is still wide open, and it is not really known yet what set of language or compiler features is a "sweet spot" for solving OS problems. So to answer your question:
In today's production systems, C is still "it."
For the operating systems of the future, C is almost certainly not "it"—we know that it is possible to do much better—but the exact nature of the new "it" is still a wide-open question.
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I think it's safe to say that low-level parts of operating systems (e.g. the kernel) will continue to be written in C because of its speed. Like mentioned elsewhere, you will need to know assembler for certain parts of the kernel (something needs to load the kernel into memory). But you can work on the kernel with little or no assembly knowledge. A good example would be if you're implementing a file system.
Don't worry about what language the operating system is implemented in. What's important is how an operating systems are used, and what can be done to improve them. A good example is when Unix first came out. The file system had the inodes at the front of the disk, and data in the remaining space. This didn't perform very well as you were seeking to different parts of the disk for all files. Then the Berkeley Fast File System was created to make a disk aware file system. This means having inodes near their corresponding data. I'm leaving out a lot of details, but I hope this illustrates that it's more important to think about how an operating system can be improved rather than what language it will be programmed in.
Some recent trends in operating systems are virtualization and distributed computing (see Google's paper on MapReduce). File systems, security, scheduling (especially with multi-core processors), etc are continually areas of interest even though these problems are not new.
Here are some resources if you want to learn more about kernel development:
Bottom line: Start getting familiar with the kernel and read papers on what researchers are writing about (USENIX is useful for this). This knowledge is much more valuable than learning a new language, as most concepts from one language can easily be transferred to another if there does happen to be a shift in what operating systems are written. Hope this helps!
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Cody didn't want to be bothered answering this, so I'm passing this on on his behalf. :-P For some examples of OSs written in managed languages, as opposed to C or assembly, look at:
Of course, Cody also didn't want to mention this:
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C is pretty much it, with a fair amount of assembler. Important topics for OS kernel work include:
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Actualy, there is quite a bit of room in the core of a modern OS for C++ code. I just looked and the Win7 core kernel tree has quite a bit of C++ code. Note that many sub-systems remain in simple C. There are a few reasons for this
That being said, many teams and people have found well written C++ to be an effective tool for core OS work.
There is nothing about C++ that prevents it from being used to write core resource management code like a scheduler, memory manger, I/O subsystem, graphics sub-system, etc. etc.
As others have pointed out - any kernel work will always require some bit of assembly language.
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Microsoft is in the process of rewriting some of Windows in .NET however I doubt that much of the kernel will be touched.
However there are projects like Cosmos ( http://www.gocosmos.org/index.en.aspx ) which give us hope.
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No, it is not "it". Kernels are generally written in C with a bit of assembler sprinkled in. But the OS is written in all sorts of language. But even there, C++ can be used without too much trouble. So can many other languages. Linux is written by C fanatics who fear and loathe everything else, which is their problem. Windows is written in a big mix of C and C++, and probably with a some bits of old Pascal code as well. And these days, chunks of .NET are turning up as well. OS X uses Objective-C for much of the OS code.
The same advice applies as in all other areas of programming:
The kernel is the only area where somewhat "special" rules apply. But the kernel is tiny. The vast majority of the OS can be written in any language.
You'll certainly need to know C, yes, but just knowing C is nowhere near enough.
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You might want to have a look at the Singularity project from Microsoft (also on Wikipedia):
Singularity is an experimental operating system being built by Microsoft Research since 2003. It is intended as a highly-dependable OS in which the kernel, device drivers, and applications are all written in managed code.
Only an extremely small part of this OS is actually written in C, and the rest is written in higher level languages (Sing#, an extension of C#). In the future I believe you can expect to see much more of this kind of thing becoming available.
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I think its a pretty safe bet that serious (non experimental) OS development will remain in C (and assembly) for the forseeable future.
The proof I submit is Ada. It can get as bare-metal as C, provides better control over data placement, and has safer default behavior for just about everything (eg: array bounds checking). From the point of view of an OS developer, it is either equal or superior to C in any technical parameter you can think up. It has been available for over 20 years now (ok...reasonably-priced for perhaps only 15).
So if people were looking for a technically superior language to C, you should see OSes all over the place written in Ada instead right? What I actually see is one serious OS implemented in Ada. It is no longer supported in favor of a reimplementation in C.
The barriers to other languages in OS development are not and never have been technical. I don't see C's non-technical benifits going away any time soon, and nobody is ever going to overcome them by simply designing a better language.
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