libkern/kmod/README

   1 #
   2 # Subtle combination of files and libraries make up the C++ runtime system for
   3 # kernel modules.  We are dependant on the KernelModule kmod.make and
   4 # CreateKModInfo.perl scripts to be exactly instep with both this library
   5 # module and the libkmod module as well.
   6 #
   7 # If you do any maintenance on any of the following files make sure great
   8 # care is taken to keep them in Sync.
   9 #    extenTools/KernelModule.bproj/kmod.make
  10 #    extenTools/KernelModule.bproj/CreateKModInfo.perl
  11 #    IOKitUser/kmodc++/pure.c
  12 #    IOKitUser/kmodc++/cplus_start.c
  13 #    IOKitUser/kmodc++/cplus_start.c
  14 #    IOKitUser/kmodc/c_start.c
  15 #    IOKitUser/kmodc/c_stop.c
  16 #
  17 # The trick is that the linkline links all of the developers modules.
  18 # If any static constructors are used .constructors_used will be left as
  19 # an undefined symbol.  This symbol is exported by the cplus_start.c routine
  20 # which automatically brings in the appropriate C++ _start routine.  However
  21 # the actual _start symbol is only required by the kmod_info structure that
  22 # is created and initialized by the CreateKModInfo.perl script.  If no C++
  23 # was used the _start will be an undefined symbol that is finally satisfied
  24 # by the c_start module in the kmod library.
  25 #
  26 # The linkline must look like this.
  27 #    *.o -lkmodc++ kmod_info.o -lkmod
  28 #