+ Cosmos (C# Open Source Managed Operating System) + is an operating system development kit which uses Visual Studio as its + development environment. Despite C# in + the name any .NET based language can be used including VB.NET, Fortran, Delphi + Prism, IrinPython, F# and more. Cosmos itself and the kernel routines are + primarly written in C#, and thus the Cosmos name. Besides that, NOSMOS (.NET + Open Source Managed Operating System) sounds stupid.
++ Cosmos is not an operating system in the traditional sense, but instead it is + "Operating System Kit", or as I like to say "Operating System Legos". + Cosmos lets you create oeprating systems just as Visual Studio and C# normally + let you create applications. Most users can write and + boot their own operating system in just a few minutes, all using Visual Studio. + Milestone 5 includes new features such as an integrated project type in Visual + Studio, and an integrated debugger. You can debug your operating system directly + from Visual Studio using breakpoints.
++ Cosmos is available in two distributions, the developer kit (dev kit), and the + user kit. The dev kit is designed for users who want to work on Cosmos itself. + The user kit is designed for those who are interested in building their own + operating system and doing some Cosmos work. The dev kit might be though of as + the Cosmos SDK. Most users should start off with the user kit as it is not so + overwhelming like the dev kit. This article focuses on the user kit.
++ Create a new project as you would any C# project. Select Cosmos as the project + type.
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+ A starter project will be created. It looks very much like a standard C# console + application.
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+ Program.cs contains the boot and execution code. Instead of seeing a Windows + console window, you will see the following:
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+ This is your operating system running in VMWare Player! Cosmos can of course + also be booted in VMWare Workstation, Hyper-V, Virtual PC, or on real hardware. + But by default Cosmos uses VMWare Player because it is both free, and reliable. + Cosmos can even debug in Visual Studio, even when running on another machine.
++ Debugging is a major issue with operating system development. The Cosmos team + was not content enough to simply conquer building and deployment, we want to + make developing operating system as easy as developing Windows applications. + Debugging a Cosmos based operating system should feel very familiar to you. Lets + set a breakpoint.
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++ TThis is the demo, booted directly to hardware. There is no need for Windows, + Linux or any other operating system to run this code. During the boot process + you may notice SysLinux. SysLinux however is not a Linux distribution, but + instead just a boot loader used to read files from the disk. We use SysLinux + instead of Grub because it has support for PXE and other options. SysLinux is + only used for initial loading of the Cosmos binaries and as soon as Cosmos is + loaded SysLinux is unloaded is not used to run Cosmos code.
++ Ease of use, or what I like to call "Nail the basics" is a priority for us. + However graphics and other things will follow in the future. Currently we are + working on a wide range of file systems including FAT and ext2. We are also + working on Ethernet support and can already send basic UDP packets, and are + working on TCP support as well.
++ Debugging operating systems is typically inconvenient and hinders progress. + Because of this, just as we did with making the build and boot process, we + strived to make the debugging process easy. The debugger is still a work in + progress, but is already quite advanced for an operating system debugger.
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+ Adding the Cosmos.Debug namespace gives the code access to communicate directly + with the debugger.
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+ In the Guess demo I am adding a Debugger.Send, which will write a debug string + to the debugger. These can be used to track code execution, but can also be used + for watching variables. In this case I will use it to write out the magic + number.
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+ Notice I have also added a Debugger.Break. This will force the program to + execute a breakpoint at that location.
++ Now let's run the Guess again. Which demo is booted is selected in Visual Studio + simply by selecting it as the startup project for the solution.
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+ This time in debugger options Source and User Only is selected. Source tells the + debugger to debug C# code, rather than the lower level IL. And User Only tells + the debugger not to trace into the Cosmos Kernel or the .NET libraries. This + speeds up execution, but also lets me focus on tracing just the demo code.
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+ Note that this time it did prompt us for the number yet? This is because it hit + the breakpoint. Another window will appear as well, this is the Cosmos Debugger.
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+ The message and breakpoint are displayed in the trace log, and the code is + selected for the breakpoint. Breakpoints occur on the next statement after the + requested break.
++ Now we can use the Step button (F11, just like Visual Studio) to step through + the code. Each step is recorded in the trace log and previous items can be + selected to walk backwards through the code. The trace log functions similarly + to the call stack window in Visual Studio.
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+ Press continue (F5) and the code will run again until a breakpoint is + encountered in code, or requested from the debugger. After continue, a new + button will appear to that allows a forced instant break. After continue, the + code will continue and we will be prompted for the number.
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+ We can also turn tracing on and off for specific sections of code using the + Cosmos.Debug namespace.
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+ This will cause the trace log to be populated with all statement executions + between the TraceOn and TraceOff without needing to step through each statement + manually.
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+ This time Cosmos & User is selected to show more details in the trace log. + Normally this option is only needed by developers working on Cosmos kernel + source.
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