* dmd main.d => main.o
  * dmd object.d => object.o
  * ld => kernel.sys
ld: warning: cannot find entry symbol _start; defaulting to 00100000
main.o: In function `gcc2_compiled.':
main.d:(.text+0x8): undefined reference to `_Dmodule_ref'
object.o: In function `gcc2_compiled.':
object.d:(.text+0x8): undefined reference to `_Dmodule_ref'