mirror of
https://github.com/danbulant/Cosmos
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147 lines
5.6 KiB
Markdown
147 lines
5.6 KiB
Markdown
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### Introducing Cosmos
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Cosmos (C# Open Source Managed Operating System) is an operating system
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development kit which uses Visual Studio as its development environment.
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Despite C# in the name any .NET based language can be used including VB.NET,
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Fortran, Delphi Prism, IronPython, F# and more. Cosmos itself and the kernel
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routines are primarily written in C#, and thus the Cosmos name. Besides that,
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NOSMOS (.NET Open Source Managed Operating System) sounds stupid.
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Cosmos is not an operating system in the traditional sense, but instead it is
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an "Operating System Kit", or as I like to say "Operating System Legos".
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Cosmos lets you create operating systems just as Visual Studio and C# normally
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let you create applications. Most users can write and boot their own operating
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system in just a few minutes, all using Visual Studio. Since milestone 5,
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Cosmos includes an integrated project type in Visual Studio, and an
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integrated debugger. You can debug your operating system directly from Visual
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Studio using breakpoints.
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Cosmos is available in two distributions, the developer kit (dev kit), and the
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user kit. The dev kit is designed for users who want to work on Cosmos itself.
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The user kit is designed for those who are interested in building their own
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operating system and doing some Cosmos work. The dev kit might be thought of
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as the Cosmos SDK. Most users should start off with the user kit as it is not
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so overwhelming like the dev kit. This article focuses on the user kit.
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### Writing your first Operating System
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Create a new project as you would any C# project, but select Cosmos as the
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project type.
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A starter project will be created. It looks very much like a standard C#
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console application.
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Program.cs contains the boot and execution code. Instead of seeing a Windows
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console window, you will see the following:
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This is your operating system running in VMWare Player! Cosmos can of course
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also be booted in VMWare Workstation, Hyper-V, Virtual PC, or on real
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hardware. But by default Cosmos uses VMWare Player because it is both free,
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and reliable. Cosmos can even debug in Visual Studio, even when running on
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another machine.
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### Integrated Debugging
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Debugging is a major issue with operating system development. The Cosmos team
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was not content enough to simply conquer building and deployment, we want to
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make developing operating system as easy as developing Windows applications.
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Debugging a Cosmos based operating system should feel very familiar to you.
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Lets modify our project a little bit to show the effect, and set a breakpoint.
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Now run the project again.
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Note that the execution stopped at "Two"? That is becuase in Visual Studio our
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project has stopped on a breakpoint. Simply press F5 to continue just as you
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would in a normal application!
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In addition to breakpoints Cosmos also supports step into (F11) as well. Trace
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over (F10) is not supported yet.
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### Debugger Communication
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The debugger uses the serial port to communicate. Because of this, debugging
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only works wtih virtualization environments that support serial ports such as
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VMWare. QEMU supports serial ports as well, but its serial port implementation
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is seriously broken on Windows and makes debugging impossible using QEMU. To
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debug on real hardware, you must use a physical serial cable. In the future
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Cosmos will also support debugging over Ethernet.
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### Extra Debugging
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Cosmos supports some explicit methods that can be used to communicate with the
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debugger and use additional functionality. It is accessed using the Debugger
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class in the Cosmos.Debug namespace in the Cosmos.Kernel assembly. This
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assembly is used by all Cosmos projects.
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### Code Based Breakpoints
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Global.Dbg.Break();
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Break can be used to issue a code based break. Visual Studio will break on the
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line after this statement.
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Since Cosmos does not support conditional breakpoints in the IDE yet, code
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base breaks are very useful for implementing such. For example:
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```csharp
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if (x == 5) {
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Global.Dbg.Break();
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}
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```
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Alternatively you can call the .NET class libary break:
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System.Diagnostics.Debugger.Break();
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Both functions will produce the same result.
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### Debug Output
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Debug strings can be output to the debug window of the host. Because Cosmos
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does not support watches yet, this functionality can be very useful for
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watching variable values and for performing tracing without breakpoints.
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```csharp
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Global.Dbg.Send("Hello from Cosmos!");
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```
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When this line is executed, it will send a message over the debugging channel
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and it will appear in the Visual Studio output window.
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### What's the catch?
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There really is no catch. Everything I've shown here is functioning as seen.
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No mockups were used. However we still have a lot of work to go. Items of
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interest that are on our current task list include interfaces (necessary for
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foreach), file systems (partial support exists), threads, networking, and
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graphics. We have prototypes and experimentation for each, but none have been
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rolled into the mainline Cosmos development as of yet.
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### What was that Syslinux thing I saw on boot?
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Cosmos does not run on Linux. A boot loader called Syslinux is used to boot
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Cosmos. After booting, Syslinux is not used. Syslinux is a bootloader and is
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not a Linux distro.
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### Obtaining Cosmos
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* [Source Code - Both dev kit and user kit](http://github.com/CosmosOS/Cosmos/)
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* [Releases](https://github.com/CosmosOS/Cosmos/releases)
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