#	$OpenBSD: bsd.README,v 1.81 2019/04/02 12:59:56 jsg Exp $
#	$NetBSD: bsd.README,v 1.17 1996/04/13 02:08:08 thorpej Exp $
#	@(#)bsd.README	5.1 (Berkeley) 5/11/90

This is the README file for the make "include" files for the BSD
source tree.  The files are installed in /usr/share/mk, and are, by
convention, named with the suffix ".mk".

bsd.dep.mk		- handle Makefile dependencies
bsd.lib.mk		- support for building libraries
bsd.man.mk		- installing manual pages and their links
bsd.obj.mk		- creating 'obj' directories and cleaning up
bsd.own.mk		- define common variables
bsd.port.mk		- building ports
bsd.port.arch.mk	- glue for building ports with MD stuff
bsd.port.subdir.mk	- targets for building subdirectories for ports
bsd.prog.mk		- building programs from source files
bsd.regress.mk		- regression tests
bsd.subdir.mk		- targets for building subdirectories
bsd.sys.mk		- overrides for <sys.mk> for building OpenBSD
sys.mk			- global default rules, mostly POSIX

Note, this file is not intended to replace reading through the .mk
files for anything tricky.

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RANDOM THINGS WORTH KNOWING:

The files are simply C-style #include files, and pretty much behave like
you'd expect.  The syntax is slightly different in that a single '.' is
used instead of the hash mark, i.e. ".include <bsd.prog.mk>".

One difference that will save you lots of debugging time is that inclusion
of the file is normally done at the *end* of the Makefile.  The reason for
this is because .mk files often modify variables and behavior based on the
values of variables set in the Makefile.  To make this work, remember that
the FIRST target found is the target that is used, i.e. if the Makefile has:

	a:
		echo a
	a:
		echo a number two

the command "make a" will echo "a".  To make things confusing, the SECOND
variable assignment is the overriding one, i.e. if the Makefile has:

	a=	foo
	a=	bar

	b:
		echo ${a}

the command "make b" will echo "bar".  This is for compatibility with the
way the V7 make behaved.

To make things even more confusing, make uses lazy evaluation. All
variables are expanded only when needed. Which means that, in

	a=	foo

	b: $(a)
		echo $(.ALLSRC)
		echo $(a)

	foo:
		touch foo

   	a=	bar

the command "make b" will echo "foo"; echo "bar".  The first $(a) means
"foo", because it's needed to generate the dependency rule when it's read,
but the second $(a) is only expanded when needed, at which point a contains
bar.

It's fairly difficult to make the BSD .mk files work when you're building
multiple programs in a single directory.  It's a lot easier to split up the
programs than to deal with the problem.  Most of the agony comes from making
the "obj" directory stuff work right, not because we switched to a new version
of make.  So, don't get mad at us, figure out a better way to handle multiple
architectures so we can quit using the symbolic link stuff.  (Imake doesn't
count.)

Dependencies are handled using the compiler's -M* options, resulting in
lots of .d files. These are manually included through <bsd.dep.mk>.

<bsd.dep.mk> also provides an empty depend target to <bsd.prog.mk> and
<bsd.lib.mk>, for backward compatibility.

The variable DESTDIR works as before.  It's not set anywhere but will change
the tree where the file gets installed.

The profiled libraries are no longer built in a different directory than
the regular libraries.  A new suffix, ".po", is used to denote a profiled
object.

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The include file <sys.mk> has the default rules for all makes, in the BSD
environment or otherwise.  You probably don't want to touch this file.

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The include file <bsd.sys.mk> is used by <bsd.prog.mk> and
<bsd.lib.mk>.  It overrides parts of <sys.mk> for building the
OpenBSD source tree.  For example, it contains a better yacc(1)
rule assigning the proper names to all output files.

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The include file <bsd.man.mk> handles installing manual pages and their
links.

It has a single target:

	maninstall:
		Install the manual pages and their links.

It sets/uses the following variables:

MANDIR		Base path for manual installation.

MANGRP		Manual group.

MANOWN		Manual owner.

MANMODE		Manual mode.

MANSUBDIR	Subdirectory under the manual page section, i.e. "amd64"
		or "sparc64" for machine specific manual pages.

MAN		The manual pages to be installed (use a .1 - .9 suffix).

MLINKS		List of manual page links (using a .1 - .9 suffix).  The
		linked-to file must come first, the linked file second,
		and there may be multiple pairs.  The files are soft-linked.

BEFOREMAN	List of extra targets that must be already built before the
		man target can be run. Those targets must be real files (and
		not .PHONY targets).

The include file <bsd.man.mk> includes a file named "../Makefile.inc" if
it exists.

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The include file <bsd.own.mk> contains source tree configuration parameters,
such as the owners, groups, etc. for both manual pages and binaries, and
a few global "feature configuration" parameters.

It has no targets.

To get system-specific configuration parameters, bsd.own.mk will try to
include the file specified by the "MAKECONF" variable.  If MAKECONF is not
set, or no such file exists, the system make configuration file, /etc/mk.conf
is included.  These files may define any of the variables described below.

bsd.own.mk sets the following variables, if they are not already defined
(defaults are in brackets):

BSDSRCDIR	The real path to the system sources, so that 'make obj'
		will work correctly. [/usr/src]

BSDOBJDIR	The real path to the system 'obj' tree, so that 'make obj'
		will work correctly. [/usr/obj]

BINGRP		Binary group. [bin]

BINOWN		Binary owner. [root]

BINMODE		Binary mode. [555]

NONBINMODE	Mode for non-executable files. [444]

DIRMODE		Mode for new directories. [755]

MANDIR		Base path for manual installation. [/usr/share/man/man]

MANGRP		Manual group. [bin]

MANOWN		Manual owner. [root]

MANMODE		Manual mode. [${NONBINMODE}]

LIBDIR		Base path for library installation. [/usr/lib]

LIBGRP		Library group. [${BINGRP}]

LIBOWN		Library owner. [${BINOWN}]

LIBMODE		Library mode. [${NONBINMODE}]

DOCDIR		Base path for system documentation
	        installation. [/usr/share/doc]

DOCGRP		Documentation group. [bin]

DOCOWN		Documentation owner. [root]

DOCMODE		Documentation mode. [${NONBINMODE}]

INSTALL_STRIP	The flag passed to the install program to cause the binary
		to be stripped.  This is to be used when building your
		own install script so that the entire system can be made
		stripped/not-stripped using a single knob.  Note that
		INSTALL_STRIP is not set if ${DEBUG} is defined. [-s]

INSTALL_COPY	The old usage of this flag is obsolescent since install(1)
		now copies by default.  However, it can also be used to
		specify that a file not be copied unless it is different
		(via the -p option).  See install(1) for details.  This
		is to be used when building our own install script so
		that the entire system can either be installed with copies,
		or copy-if-different using a single knob. [-c]

Additionally, the following variables may be set by bsd.own.mk or in a
make configuration file to modify the behaviour of the system build
process (default values are in brackets along with comments, if set by
bsd.own.mk):

SKEY		Compile in support for S/key authentication. [yes, set
		unconditionally]

SYS_INCLUDE	Copy or symlink kernel include files into /usr/include.
		Possible values are "symlinks" or "copies" (which is
		the same as the variable being unset).

NOPROFILE	Do not build profiled versions of system libraries.

NOPIC		Do not build PIC versions of system libraries, and
		do not build shared libraries.

NOPIE		Do not build PIE objects or executables.

DEBUG		Add -g to assembly, C compiler and linking passes.  Also
		doesn't	set STRIP to -s per default if defined.

WARNINGS	Adds appropriate warning flags (defined in CDIAGFLAGS,
		e.g., -Wall...) to compiles. [no]

SUDO		Command to run when doing "make install" portion of
		"make build".  If set to /usr/bin/doas, this allows one
		to run "make build" as a user other than root (assuming
		doas is setup for that user).

PIPE		If set to "-pipe" gcc will be given the -pipe option
		which can speed up compiles on machines with memory
		to spare.  Instead of using temp files, gcc uses pipes
		for the temporary data.

GLOBAL_AUTOCONF_CACHE
		Set to the name of a file that all cached GNU autoconf
		test results will be saved in.	Reduces redundant tests.
		Be careful!  Redundant tests may not be redundant if you
		are installing substantially updated gnu programs.

bsd.own.mk is generally useful when building your own Makefiles so that
they use the same default owners etc. as the rest of the tree.

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The include file <bsd.prog.mk> handles building programs from one or
more source files, along with their manual pages.  It has a limited number
of suffixes, consistent with the current needs of the BSD tree.

It has six targets:

	all:
		build the program and its manual page
	clean:
		remove the program, any object files, and some other
		files that are automatically generated.
	cleandir:
		remove all of the files removed by the target clean, as
		well as the tags file.
	includes:
		install any header files.
	install:
		install the program and its manual pages; if the Makefile
		does not itself define the target install, the targets
		beforeinstall and afterinstall may also be used to cause
		actions immediately before and after the install target
		is executed.
	tags:
		create a tags file for the source files.

It uses the following variables:

BINGRP		Binary group.

BINOWN		Binary owner.

BINMODE		Binary mode.

BUILDFIRST	Stuff that needs to be built before anything else, in
		terms of dependencies.

BUILDAFTER	Stuff that comes later (usually don't touch, defined correctly
		by <bsd.prog.mk> and <bsd.lib.mk>)

CLEANFILES	Additional files to remove for the clean and cleandir targets.

COPTS		Additional flags to the compiler when creating C objects.

LDADD		Additional linker objects.  Usually used for libraries.
		For example, to link with the crypto and utility
		libraries, use:

			LDADD+=-lutil -lcrypto

LDFLAGS		Additional linker flags.

LINKS		The list of binary links; should be full pathnames, the
		linked-to file coming first, followed by the linked
		file.  The files are hard-linked.  For example, to link
		/bin/test and /bin/[, use:

			LINKS=	${DESTDIR}/bin/test ${DESTDIR}/bin/[

MAN		Manual pages (should end in .1 - .9).  If no MAN variable is
		defined, "MAN=${PROG}.1" is assumed.

PROG		The name of the program to build.  If not supplied, nothing
		is built.

SRCS		List of source files to build the program.  If it's not
		defined, it's assumed to be ${PROG}.c.

DPADD		Additional dependencies for the program.  Usually used for
		libraries.  For example, to depend on the crypto and
		utility libraries use:

			DPADD+=${LIBCRYPTO} ${LIBUTIL}

		The following libraries are predefined for DPADD:

			LIBC		/usr/lib/libc.a
			LIBCRYPTO	/usr/lib/libcrypto.a
			LIBCURSES	/usr/lib/libcurses.a
			LIBEDIT		/usr/lib/libedit.a
			LIBELF		/usr/lib/libelf.a
			LIBEVENT	/usr/lib/libevent.a
			LIBEXPAT	/usr/lib/libexpat.a
			LIBFORM		/usr/lib/libform.a
			LIBFORMW	/usr/lib/libformw.a
			LIBKEYNOTE	/usr/lib/libkeynote.a
			LIBKVM		/usr/lib/libkvm.a
			LIBL		/usr/lib/libl.a
			LIBM		/usr/lib/libm.a
			LIBMENU		/usr/lib/libmenu.a
			LIBMENUW	/usr/lib/libmenuw.a
			LIBRADIUS	/usr/lib/libradius.a
			LIBOSSAUDIO	/usr/lib/libossaudio.a
			LIBPANEL	/usr/lib/libpanel.a
			LIBPANELW	/usr/lib/libpanelw.a
			LIBPCAP		/usr/lib/libpcap.a
			LIBPERL		/usr/lib/libperl.a
			LIBPTHREAD	/usr/lib/libpthread.a
			LIBRPCSVC	/usr/lib/librpcsvc.a
			LIBSKEY		/usr/lib/libskey.a
			LIBSNDIO	/usr/lib/libsndio.a
			LIBSSL		/usr/lib/libssl.a
			LIBTERMCAP	/usr/lib/libtermcap.a
			LIBTERMLIB	/usr/lib/libtermlib.a
			LIBTLS		/usr/lib/libtls.a
			LIBUSB		/usr/lib/libusbhid.a
			LIBUTIL		/usr/lib/libutil.a
			LIBY		/usr/lib/liby.a
			LIBZ		/usr/lib/libz.a
			LIBARCH		arch-dependent stuff

STRIP		The flag passed to the install program to cause the binary
		to be stripped.

SUBDIR		A list of subdirectories that should be built as well.
		Each of the targets will execute the same target in the
		subdirectories.

The include file <bsd.prog.mk> includes the file named "../Makefile.inc"
if it exists, as well as the include file <bsd.man.mk>.

Some simple examples:

To build foo from foo.c with a manual page foo.1, use:

	PROG=	foo

	.include <bsd.prog.mk>

To build foo from foo.c with a manual page foo.2, add the line:

	MAN=	foo.2

If foo does not have a manual page at all, add the line:

	NOMAN=	noman

If foo has multiple source files, add the line:

	SRCS=	a.c b.c c.c d.c

SRCS may contain lex and yacc files, in which case the framework will
convert these files to C and header files first, before building anything
else.

SRCS may contain C++ files, in which case the C++ compiler will be used
for linking.

If YFLAGS contains -d, the header file will be named like the C file,
and a proper rule tying both together will be generated. For instance, if
SRCS contains grammar.y, then effectively you will have

grammar.c grammar.h: grammar.y
	${YACC.Y} -o grammar.c grammar.y


<bsd.prog.mk> provides a limited capability to build several
programs in a single directory by defining the list of programs
as PROGS instead of using PROG, for instance: PROGS = foo bar

This only works if all programs in the directory use the same
compiler and linker flags.  Also, the programs cannot use source
files with the same file name but different content.

Each program of the list, for instance foo, will use SRCS_foo instead
of SRCS to find its sources.  SRCS_foo still defaults to foo.c, and
MAN still defaults to section 1 manpages: MAN = foo.1 bar.1.

Each program can have its separate LDADD_foo and DPADD_foo definitions.
If not defined, these default to LDADD/DPADD.

Some simple examples:
To build foo from foo.c and bar from bar.c with manual pages foo.1 and bar.1:

	PROGS = foo bar

	.include <bsd.prog.mk>

If bar has manual page bar.8 instead, add the line:
	MAN = foo.1 bar.8

If bar has multiple source files, add the line:
	SRCS_bar = a.c b.c c.c d.c

Note that foo and bar may share some source files, like so:
	SRCS_foo = foo.c common.c
	SRCS_bar = bar.c common.c

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The include file <bsd.subdir.mk> contains the default targets for building
subdirectories.  It has the same six targets as <bsd.prog.mk>: all,
clean, cleandir, includes, install, and tags.  For all of
the directories listed in the variable SUBDIR, the specified directory
will be visited and the target made.  There is also a default target which
allows the command "make subdir" where subdir is any directory listed in
the variable SUBDIR.


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The include file <bsd.lib.mk> has support for building libraries.  It has
the same six targets as <bsd.prog.mk>: all, clean, cleandir,
includes, install, and tags.  It has a limited number of suffixes,
consistent with the current needs of the BSD tree.

It uses the following variables:

BUILDFIRST/BUILDAFTER
		See <bsd.prog.mk>.

LIB		The name of the library to build.

LIBDIR		Target directory for libraries.

LIBGRP		Library group.

LIBOWN		Library owner.

LIBMODE		Library mode.

LDADD		Additional linker objects.

MAN		The manual pages to be installed (use a .1 - .9 suffix).

SRCS		List of source files to build the library.  Suffix types
		.s, .c, and .f are supported.  Note, .s files are preferred
		to .c files of the same name.  (This is not the default for
		POSIX make without bsd.lib.mk).

		The same support for yacc and lex files as <bsd.prog.mk>
		is provided.

The include file <bsd.lib.mk> includes the file named "../Makefile.inc"
if it exists, as well as the include file <bsd.man.mk>.

It has rules for building profiled objects; profiled libraries are
built by default.

Static libraries are ranlib'd when made.

In addition, a reduced version of a library, including just specific
objects that are compiled with additional options to reduce their
size may be built.  This is used by the distrib/ tree and crunchgen
when building ramdisks.  This sets/uses the following variables:

DIST_LIB	The path of the library to build. [lib${LIB}_d.a]

DIST_OBJS	The (sub)set of .o files to include in ${DIST_LIB}. [${OBJS}]

DIST_CFLAGS	Additional flags for the C compiler and assembler.
		[-Oz]

