C++ OS?
Posted: Tue Apr 20, 2004 11:00 pm
What support stubs, etc... would I have to write to write an OS kernel in C++? Also, what C++ features should I turn off while compiling?
Really, there isn't much. If you're using GCC, you just need the following.
(1) Basic C runtime library with malloc/realloc/free. I use the newlib library that I can build with the rest if te GCC toolchain, which mean I only have to supply an sbrk() function underneath malloc et al.
(2) Basic C++ runtime startup: this requires a prologue and epilogue written in assembler. One assembler file, 3 lines. The rest is linker script magic.
(3) Interrupt trampoline stubs, one per interrupt/trap. You need this for a C-based kernel, too. One assembler file, about 20 lines.
(4) Boot code -- if you're using a multiboot-compliant bootloader all you need to do is set up the stack, push some args, and call out into C++. One assembler file, three lines.
That's it. The rest is all C++, including virtual functions, RTTI, exceptions, dynamic allocation, STL, templates.
I don't turn off any C++ features while compiling, since I use them all. It just works.