C Sharp Bare Bones: Difference between revisions

 

This tutorial is intended to help you write a simple 'Hello World' OS in [[C Sharp | C#]] which you can then compile to machine code for the IA32 architecture and boot via [[GRUB]]. There are a number of tools for compiling C# to [[CIL]], including Microsoft's csc (distributed with [http://www.microsoft.com/net Microsoft.NET]) and mcs/gmcs/dmcs (distributed with [http://www.mono-project.com Mono]). In addition there are a number of tools for compiling [[CIL]] to native machine code in an ahead-of-time manner, including Microsoft's ngen, mono (with the --aot option), [http://gocosmos.org Cosmos'] IL2CPU, mosacl from the [http://www.mosa-project.org/projects/mosa MOSA project] and tysila from the [http://www.tysos.org/redmine/projects/tysos/ tysos] project. Given the author's familiarity with tysos, that is what we will focus on here.

 

==Prerequisites==

 

This is only required if you have not downloaded the pre-compiled binaries above. Use subversion to get the latest sources 'svn co http://www.tysos.org/svn/trunk tysos' (not in Wayback Machine), or download the latest tar ball from http://www.tysos.org/files/src/tysos-latest.tar.bz2 (http://web.archive.org/web/*/http://www.tysos.org/files/src/tysos-latest.tar.bz2). Tysos is a project developing a full OS kernel and drivers in C#, however we only want the compiler from it therefore we only want to compile part of the build tree. Enter the tysos directory and run

cd tybuild && make && cd ..

cd mono/corlib && make mscorlib.dll && cd ../..

cd tysila2 && make && cd ..

 

You will need to put the mono/corlib/mscorlib.dll, tysila2/bin/Release/tysila2.exe, tysila2/bin/Release/libsupcs.dll, tysila2/bin/Release/libtysila.dll, tysila2/bin/Release/tydbfile.dll, tysila2/bin/Release/tydisasm.dll and tybuild/bin/Release/tybuild.exe files somewhere in your path.

This is the assembly stub which will contain a Multiboot header.

 

global sthrow

 

hlt

jmp sthrow

 

===kernel.cs===

This is the actual simple kernel - it just prints a message to the screen.

 

namespace BareBones

{

}

}

 

===linker.ld===

The linker script

 

ENTRY (_start)

 

}

}

 

===iso/boot/grub/grub.cfg===

This is a short file to tell grub where to find our kernel

multiboot /kernel.bin

boot

 

==Building it all==

The following commands should build your new C# kernel. First, assemble the multiboot stub:

To compile the .cs file to a .exe you have a choice of three options (depending on your architecture):

gmcs /target:exe /out:kernel.exe /unsafe kernel.cs

csc /target:exe /out:kernel.exe /unsafe kernel.cs

tybuild.exe /unsafe kernel.cs

To compile kernel.exe to machine code we use tysila:

Here, the -fno-rtti switch disables run-time type information, support for which would greatly enlarge the size of your kernel and require you to provide a great number of run time functions to support this.

 

To link:

 

Then we make a bootable iso image with:

 

And run it on qemu with:

 

[[Category:Bare bones tutorials]]