osdev-d-barebones/kernel_main.d

extern (C) void mykernel_main() {
    write("Hello from D!");
}

void write(string message) {
    ubyte * vidmem = cast(ubyte *) 0xB8000u;
    for (size_t i = 0u; message[i] != '\0'; i++) {
        vidmem[i * 2] = message[i];
        vidmem[i * 2 + 1] = 7u;
    }
}