where is the build rules for drivers/* ?

[horseriver]

hi:

  when building kernel , kbuild will work into every subdirs .
 
  for example:  drivers/acpi directory ,there is a makefile , which construct all  object files 
  ,but where is the building rules for these file? how kbuild build them out ?

  Is script/makefile.build doing this work?
  

thanks!