Fiasco's build system Michael Hohmuth Motivation ########## My main goal when I designed Fiasco's build system was to allow for multiple configurations of the kernel, based on different implementations of the same interface, to coexist in multiple object directories. Configuration ############# Fiasco's build system consists of a number of configuration files, and it also makes use of the L4 source tree's global Make configuration file, l4/Makeconf. All configuration files are written in Makefile language. :l4/Makeconf: Global Make rules and search paths :l4/kernel/fiasco/src/Makefile: ``Fiasco's build system'' rules :l4/kernel/fiasco/src/Modules.in: Standard configuration for Fiasco :<object directory> /Modules: Current configuration for Fiasco :l4/kernel/fiasco/src/Makerules.*: Make rules for each subsystem defined in Modules :l4/kernel/fiasco/src/Makerules.local': (Optional) User-specific configuration files :l4/Makeconf.local': (Optional) User-specific configuration files (By default, the object directory is the main source directory, l4/kernel/fiasco/src/. See the next section on how to use other object directories with custom configurations.) Users configure the build system by creating a Modules file. If no Modules file exists, the standard configuration Modules.in is copied to Modules. The build system warns the user if (after a "cvs update") Modules.in is newer than Modules. The Modules file defines a number of subsystems that should be built. For each subsystem, there must be a Makerules.<subsystem> file that defines rules for building the subsystem's targets. In the remainder of this section, I describe by example the language used in Modules file and the contents of the Makerules.* files. !SUBSYSTEMS = FOO BAR ! # Defines two subsystems, FOO and BAR. This means that there ! # exist two files, Makerules.FOO and Makerules.BAR, that ! # contain rules on how to build the targets of these ! # subsystems. These targets are defined later. ! !### Definitions for subsystem FOO follow ! !FOO = foo ! # Defines the main target of subsystem FOO: a file named ! # "foo". ! !FOO_EXTRA = foo.man ! # (Optional) Defines more targets that should be built for ! # subsystem FOO. ! !INTERFACES_FOO = foo1 foo2 foo3 ! # (Optional) C++ modules for subsystem FOO (written in ! # `preprocess' format; see ! # <URL:http://os.inf.tu-dresden.de/~hohmuth/prj/preprocess/>) ! # Each module normally consists of one implementation file ! # such as foo1.cpp -- unless IMPL definitions such as the ! # following ones are given: ! !foo2_IMPL = foo2 foo2-more ! # (Optional) C++ module foo2 is implemented in two files ! # foo2.cpp and foo2-more.cpp (instead of just foo2.cpp). The ! # public header file generated from these implementation files ! # will be called foo2.h. ! !foo3_IMPL = foo3-debug ! # (Optional) C++ module foo3 is implemented in foo3-debug.cpp, ! # not foo3.cpp. The public header file generated from this ! # implementation file will be called foo3.h. ! !CXXSRC_FOO = frob1.cc frob2.cc ! # (Optional) Additional C++ sources for subsystem FOO (not in ! # `preprocess' format) ! !CSRC_FOO = frob3.c frob4.c ! # (Optional) Additional C sources for subsystem FOO ! !ASSRC_FOO = frob5.S ! # (Optional) Additional assembly-language sources for ! # subsystem FOO ! !OBJ_FOO = frob6.o ! # (Optional) Additional objects for subsystem FOO. These ! # objects can be precompiled or generated using custom rules ! # in Makerules.FOO. ! !NOPROFILE += frob2 ! # (Optional) Basenames of objects that should not be compiled ! # with profiling options in profiling builds. ! !NOOPT += frob3 ! # (Optional) Basenames of objects that should not be compiled ! # with optimization options. ! !PRIVATE_INCDIR += incdir ! # (Optional) Add incdir to the include path for all source ! # files. (This feature is implemented by l4/Makeconf.) ! !VPATH += foodir ! # (Optional) Add foodir to Make's source-file search ! # path. (This feature is implemented internally by Make.) ! !### Definitions for subsystem BAR follow !### (similar to FOO's definitions) The Makerules.FOO file usually contains just rules for linking the subsystem's targets. Additionally, it must contain a rule "clean-FOO:" that cleans the object directory from files created by this configuration file. It can access the following Make variables: :'FOO', 'FOO_EXTRA': names of targets :'OBJ_FOO': expanded to contain _all_ objects that will be created for subsystem FOO :'BAR': targets of other subsystems Building in separate object directories ####################################### It is possible to configure multiple directories, each with its own Modules file, as separate object directories. (This usage is supported only if the main source directory [the one containing Modules.in] is not also used as an object directory.) To use a directory as an object directory, create in it a Makefile like this: !srcdir = .. ! !all: ! !%: ! $(MAKE) -I $(srcdir) -f $(srcdir)/Makefile \ ! srcdir=$(srcdir) $@ Change the "srcdir" definition to point to the main source directory. You can then create custom Modules files (and custom source files and Makerules.* files) in each object directory.