1Each operating system must have a subdir here, with a Makefile 2The first target of that Makefile must build a file "sysdep.o" in this 3directory. 4The "clean" target of that Makefile must undo all the efects of the 5first target, and must remove "sysdep.o" in this dir. 6 7Files "sysdep.h", "signalent.h" and "syscallent.h" must be present 8inside the directory after invoking the first target of the Makefile. 9 10See the file "backend.h" for description of backend interfaces, which 11have to be provided by "sysdep.o". 12