bsd.README revision 1.75
1#	$NetBSD: bsd.README,v 1.75 2001/02/01 20:27:06 agc Exp $
2#	@(#)bsd.README	8.2 (Berkeley) 4/2/94
3
4This is the README file for the new make "include" files for the BSD
5source tree.  The files are installed in /usr/share/mk, and are, by
6convention, named with the suffix ".mk".
7
8Note, this file is not intended to replace reading through the .mk
9files for anything tricky.
10
11=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
12
13RANDOM THINGS WORTH KNOWING:
14
15The files are simply C-style #include files, and pretty much behave like
16you'd expect.  The syntax is slightly different in that a single '.' is
17used instead of the hash mark, i.e. ".include <bsd.prog.mk>".
18
19One difference that will save you lots of debugging time is that inclusion
20of the file is normally done at the *end* of the Makefile.  The reason for
21this is because .mk files often modify variables and behavior based on the
22values of variables set in the Makefile.  To make this work, remember that
23the FIRST target found is the target that is used, i.e. if the Makefile has:
24
25	a:
26		echo a
27	a:
28		echo a number two
29
30the command "make a" will echo "a".  To make things confusing, the SECOND
31variable assignment is the overriding one, i.e. if the Makefile has:
32
33	a=	foo
34	a=	bar
35
36	b:
37		echo ${a}
38
39the command "make b" will echo "bar".  This is for compatibility with the
40way the V7 make behaved.
41
42It's fairly difficult to make the BSD .mk files work when you're building
43multiple programs in a single directory.  It's a lot easier to split up the
44programs than to deal with the problem.  Most of the agony comes from making
45the "obj" directory stuff work right, not because we switched to a new version
46of make.  So, don't get mad at us, figure out a better way to handle multiple
47architectures so we can quit using the symbolic link stuff.  (Imake doesn't
48count.)
49
50The file .depend in the source directory is expected to contain dependencies
51for the source files.  This file is read automatically by make after reading
52the Makefile.
53
54The variable DESTDIR works as before.  It's not set anywhere but will change
55the tree where the file gets installed.
56
57The profiled libraries are no longer built in a different directory than
58the regular libraries.  A new suffix, ".po", is used to denote a profiled
59object, and ".so" denotes a shared (position-independent) object.
60
61The following variables that control how things are made/installed that
62are not set by default. These should not be set by Makefiles; they're for
63the user to define in MAKECONF (see bsd.own.mk, below) or on the make(1)
64command line:
65
66BUILD 		If defined, 'make install' checks that the targets in the
67		source directories are up-to-date and remakes them if they
68                are out of date, instead of blindly trying to install
69                out of date or non-existant targets.
70
71UPDATE 		If defined, 'make install' only installs targets that are
72		more recently modified in the source directories that their
73		installed counterparts.
74
75UNPRIVILEGED	If defined, don't set the owner/group/mode when installing
76		files or directories.  This allows a non-root "make install".
77
78MKCATPAGES	If "no", don't build or install the catman pages.
79
80MKDOC		If "no", don't build or install the documentation.
81
82MKINFO		If "no", don't build or install Info documentation from
83		Texinfo source files.
84
85MKLINT		If "no", don't build or install the lint libraries.
86
87MKMAN		If "no", don't build or install the man or catman pages.
88		Also acts as "MKCATPAGES=no"
89
90MKNLS		If "no", don't build or install the NLS files and locale
91		definition files.
92
93MKOBJ		If "no", don't enable the rule which creates objdirs.
94		"yes" by default.
95
96MKOBJDIRS	If "no", don't create objdirs during a "make build".
97		"no" by default.
98
99MKPIC		If "no", don't build or install shared libraries.
100
101MKPICINSTALL	If "no", don't install the *_pic.a libraries.
102
103MKPROFILE	If "no", don't build or install the profiling libraries.
104
105MKSHARE		If "no", act as "MKCATPAGES=no MKDOC=no MKINFO=no MKMAN=no
106		MKNLS=no".  I.e, don't build catman pages, documentation,
107		Info documentation, man pages, NLS files, ...
108
109=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
110
111The include file <sys.mk> has the default rules for all makes, in the BSD
112environment or otherwise.  You probably don't want to touch this file.
113If you intend to run a cross build, you will need to supply the following
114host tools, and configure the following variables properly:
115
116OBJCOPY		objcopy - copy and translate object files
117
118STRIP		strip - Discard symbols from object files
119
120CONFIG		config - build kernel compilation directories
121
122RPCGEN		rpcgen - Remote Procedure Call (RPC) protocol compiler
123
124MKLOCALE	mklocale - make LC_CTYPE locale files
125
126=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
127
128The include file <bsd.man.mk> handles installing manual pages and their
129links.
130
131It has a two targets:
132
133	maninstall:
134		Install the manual page sources and their links.
135	catinstall:
136		Install the preformatted manual pages and their links.
137
138It sets/uses the following variables:
139
140MANDIR		Base path for manual installation.
141
142MANGRP		Manual group.
143
144MANOWN		Manual owner.
145
146MANMODE		Manual mode.
147
148MANSUBDIR	Subdirectory under the manual page section, i.e. "/vax"
149		or "/tahoe" for machine specific manual pages.
150
151MAN		The manual pages to be installed (use a .1 - .9 suffix).
152
153MLINKS		List of manual page links (using a .1 - .9 suffix).  The
154		linked-to file must come first, the linked file second,
155		and there may be multiple pairs.  The files are soft-linked.
156
157The include file <bsd.man.mk> includes a file named "../Makefile.inc" if
158it exists.
159
160=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
161
162The include file <bsd.own.mk> contains source tree configuration parameters,
163such as the owners, groups, etc. for both manual pages and binaries, and
164a few global "feature configuration" parameters.
165
166It has no targets.
167
168To get system-specific configuration parameters, bsd.own.mk will try to
169include the file specified by the "MAKECONF" variable.  If MAKECONF is not
170set, or no such file exists, the system make configuration file, /etc/mk.conf
171is included.  These files may define any of the variables described below.
172
173bsd.own.mk sets the following variables, if they are not already defined
174(defaults are in brackets):
175
176BSDSRCDIR	The real path to the system sources, so that 'make obj'
177		will work correctly. [/usr/src]
178
179BSDOBJDIR	The real path to the system 'obj' tree, so that 'make obj'
180		will work correctly. [/usr/obj]
181
182BINGRP		Binary group. [wheel]
183
184BINOWN		Binary owner. [root]
185
186BINMODE		Binary mode. [555]
187
188NONBINMODE	Mode for non-executable files. [444]
189
190MANDIR		Base path for manual installation. [/usr/share/man/cat]
191
192MANGRP		Manual group. [wheel]
193
194MANOWN		Manual owner. [root]
195
196MANMODE		Manual mode. [${NONBINMODE}]
197
198MANINSTALL	Manual installation type: maninstall, catinstall, or both
199
200LIBDIR		Base path for library installation. [/usr/lib]
201
202LINTLIBDIR	Base path for lint(1) library installation. [/usr/libdata/lint]
203
204LIBGRP		Library group. [${BINGRP}]
205
206LIBOWN		Library owner. [${BINOWN}]
207
208LIBMODE		Library mode. [${NONBINMODE}]
209
210DOCDIR		Base path for system documentation (e.g. PSD, USD, etc.)
211	        installation. [/usr/share/doc]
212
213HTMLDOCDIR	Base path for html system documentation installation.
214		[/usr/share/doc/html]
215
216DOCGRP		Documentation group. [wheel]
217
218DOCOWN		Documentation owner. [root]
219
220DOCMODE		Documentation mode. [${NONBINMODE}]
221
222NLSDIR		Base path for National Language Support files installation.
223		[/usr/share/nls]
224
225NLSGRP		National Language Support files group. [wheel]
226
227NLSOWN		National Language Support files owner. [root]
228
229NLSMODE		National Language Support files mode. [${NONBINMODE}]
230
231STRIPFLAG	The flag passed to the install program to cause the binary
232		to be stripped.  This is to be used when building your
233		own install script so that the entire system can be made
234		stripped/not-stripped using a single knob. [-s]
235
236COPY		The flag passed to the install program to cause the binary
237		to be copied rather than moved.  This is to be used when
238		building our own install script so that the entire system
239		can either be installed with copies, or with moves using
240		a single knob. [-c]
241
242Additionally, the following variables may be set by bsd.own.mk or in a
243make configuration file to modify the behaviour of the system build
244process (default values are in brackets along with comments, if set by
245bsd.own.mk):
246
247MKCRYPTO	If set to "no", no cryptography support will be built
248		into the system.  Defaults to "yes".
249
250NOCRYPTO	If set, it is equivalent to setting MKCRYPTO to "no".
251
252MKCRYPTO_IDEA	If set to "yes", IDEA support will be built into
253		libcrypto_idea.a.  Defaults to "no".
254
255MKCRYPTO_RC5	If set to "yes", RC5 support will be built into
256		libcrypto_rc5.a.  Defaults to "no".
257
258MKKERBEROS	If set to "no", disables building Kerberos (v4 or v5)
259		support into various system utilities that support it.
260		Defaults to "yes".  NOTE: This does not affect the
261		building of the Kerberos libraries or infrastructure
262		programs themselves.  To completely disable Kerberos,
263		set MKCRYPTO to "no".
264
265NOKERBEROS	If set, it is equivalent to setting MKKERBEROS to "no".
266
267SKEY		Compile in support for S/key authentication. [yes, set
268		unconditionally]
269
270MANZ		Compress manual pages at installation time.
271
272SYS_INCLUDE	Copy or symlink kernel include files into /usr/include.
273		Possible values are "symlinks" or "copies" (which is
274		the same as the variable being unset).
275
276NOPROFILE	Do not build profiled versions of system libraries
277
278NOPIC		Do not build PIC versions of system libraries, and
279		do not build shared libraries.  [set if ${MACHINE_ARCH}
280		is "sh3" and ${OBJECT_FMT} is "COFF", unset otherwise.]
281
282NOLINT		Do not build lint libraries.
283
284OBJECT_FMT	Object file format. [set to "ELF" on architectures that
285		use ELF -- currently if ${MACHINE_ARCH} is "alpha",
286		"mipsel", "mipseb", "powerpc", "sparc", "sparc64",
287		and "i386", or set to "a.out" on other architectures].
288
289
290bsd.own.mk is generally useful when building your own Makefiles so that
291they use the same default owners etc. as the rest of the tree.
292
293=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
294
295The include file <bsd.prog.mk> handles building programs from one or
296more source files, along with their manual pages.  It has a limited number
297of suffixes, consistent with the current needs of the BSD tree.
298
299It has eight targets:
300
301	all:
302		build the program and its manual page
303	clean:
304		remove the program, any object files and the files a.out,
305		Errs, errs, mklog, and ${PROG}.core.
306	cleandir:
307		remove all of the files removed by the target clean, as
308		well as .depend, tags, and any manual pages.
309		`distclean' is a synonym for `cleandir'.
310	depend:
311		make the dependencies for the source files, and store
312		them in the file .depend.
313	includes:
314		install any header files.
315	install:
316		install the program and its manual pages; if the Makefile
317		does not itself define the target install, the targets
318		beforeinstall and afterinstall may also be used to cause
319		actions immediately before and after the install target
320		is executed.
321	lint:
322		run lint on the source files
323	tags:
324		create a tags file for the source files.
325
326It sets/uses the following variables:
327
328BINGRP		Binary group.
329
330BINOWN		Binary owner.
331
332BINMODE		Binary mode.
333
334CLEANFILES	Additional files to remove for the clean and cleandir targets.
335
336COPTS		Additional flags to the compiler when creating C objects.
337
338CPPFLAGS	Additional flags to the C pre-processor
339
340LDADD		Additional loader objects.  Usually used for libraries.
341		For example, to load with the compatibility and utility
342		libraries, use:
343
344			LDADD+=-lutil -lcompat
345
346LDFLAGS		Additional loader flags.
347
348LINKS		The list of binary links; should be full pathnames, the
349		linked-to file coming first, followed by the linked
350		file.  The files are hard-linked.  For example, to link
351		/bin/test and /bin/[, use:
352
353			LINKS=	${DESTDIR}/bin/test ${DESTDIR}/bin/[
354
355SYMLINKS	The list of symbolic links; should be full pathnames.
356                Syntax is identical to LINKS. Note that DESTDIR is not
357		automatically included in the link.
358
359MAN		Manual pages (should end in .1 - .9).  If no MAN variable is
360		defined, "MAN=${PROG}.1" is assumed.
361
362PROG		The name of the program to build.  If not supplied, nothing
363		is built.
364
365PROGNAME	The name that the above program will be installed as, if
366		different from ${PROG}.
367
368SRCS		List of source files to build the program.  If SRCS is not
369		defined, it's assumed to be ${PROG}.c.
370
371DPADD		Additional dependencies for the program.  Usually used for
372		libraries.  For example, to depend on the compatibility and
373		utility libraries use:
374
375			DPADD+=${LIBCOMPAT} ${LIBUTIL}
376
377		The following libraries are predefined for DPADD:
378
379		LIBCRT0?=	${DESTDIR}/usr/lib/crt0.o
380		LIBC?=		${DESTDIR}/usr/lib/libc.a
381		LIBC_PIC?=	${DESTDIR}/usr/lib/libc_pic.a
382		LIBCOMPAT?=	${DESTDIR}/usr/lib/libcompat.a
383		LIBCRYPT?=	${DESTDIR}/usr/lib/libcrypt.a
384		LIBCURSES?=	${DESTDIR}/usr/lib/libcurses.a
385		LIBDBM?=	${DESTDIR}/usr/lib/libdbm.a
386		LIBDES?=	${DESTDIR}/usr/lib/libdes.a
387		LIBEDIT?=	${DESTDIR}/usr/lib/libedit.a
388		LIBFORM?=	${DESTDIR}/usr/lib/libform.a
389		LIBGCC?=	${DESTDIR}/usr/lib/libgcc.a
390		LIBGNUMALLOC?=	${DESTDIR}/usr/lib/libgnumalloc.a
391		LIBINTL?=	${DESTDIR}/usr/lib/libintl.a
392		LIBIPSEC?=	${DESTDIR}/usr/lib/libipsec.a
393		LIBKDB?=	${DESTDIR}/usr/lib/libkdb.a
394		LIBKRB?=	${DESTDIR}/usr/lib/libkrb.a
395		LIBKVM?=	${DESTDIR}/usr/lib/libkvm.a
396		LIBL?=		${DESTDIR}/usr/lib/libl.a
397		LIBM?=		${DESTDIR}/usr/lib/libm.a
398		LIBMENU?=	${DESTDIR}/usr/lib/libmenu.a
399		LIBMP?=		${DESTDIR}/usr/lib/libmp.a
400		LIBNTP?=	${DESTDIR}/usr/lib/libntp.a
401		LIBPC?=		${DESTDIR}/usr/lib/libpc.a
402		LIBPCAP?=	${DESTDIR}/usr/lib/libpcap.a
403		LIBPLOT?=	${DESTDIR}/usr/lib/libplot.a
404		LIBPOSIX?=	${DESTDIR}/usr/lib/libposix.a
405		LIBRESOLV?=	${DESTDIR}/usr/lib/libresolv.a
406		LIBRPCSVC?=	${DESTDIR}/usr/lib/librpcsvc.a
407		LIBSKEY?=	${DESTDIR}/usr/lib/libskey.a
408		LIBTERMCAP?=	${DESTDIR}/usr/lib/libtermcap.a
409		LIBTELNET?=	${DESTDIR}/usr/lib/libtelnet.a
410		LIBUTIL?=	${DESTDIR}/usr/lib/libutil.a
411		LIBWRAP?=	${DESTDIR}/usr/lib/libwrap.a
412		LIBY?=		${DESTDIR}/usr/lib/liby.a
413		LIBZ?=		${DESTDIR}/usr/lib/libz.a
414
415
416SHAREDSTRINGS	If defined, a new .c.o rule is used that results in shared
417		strings, using xstr(1). Note that this will not work with
418		parallel makes.
419
420STRIPFLAG	The flag passed to the install program to cause the binary
421		to be stripped.
422
423SUBDIR		A list of subdirectories that should be built as well.
424		Each of the targets will execute the same target in the
425		subdirectories.
426
427SCRIPTS		A list of interpreter scripts [file.{sh,csh,pl,awk,...}].
428		These are installed exactly like programs.
429
430SCRIPTSNAME	The name that the above program will be installed as, if
431		different from ${SCRIPTS}. These can be further specialized
432		by setting SCRIPTSNAME_<script>.
433
434FILES		A list of files to install. The installation is controlled
435		by the FILESNAME, FILESOWN, FILESGRP, FILESMODE, FILESDIR
436		variables that can be further specialized by FILES<VAR>_<file>
437
438The include file <bsd.prog.mk> includes the file named "../Makefile.inc"
439if it exists, as well as the include file <bsd.man.mk>.
440
441Some simple examples:
442
443To build foo from foo.c with a manual page foo.1, use:
444
445	PROG=	foo
446
447	.include <bsd.prog.mk>
448
449To build foo from foo.c with a manual page foo.2, add the line:
450
451	MAN=	foo.2
452
453If foo does not have a manual page at all, add the line:
454
455	MKMAN=	no
456
457If foo has multiple source files, add the line:
458
459	SRCS=	a.c b.c c.c d.c
460
461=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
462
463The include file <bsd.subdir.mk> contains the default targets for building
464subdirectories.  It has the same eight targets as <bsd.prog.mk>: all, 
465clean, cleandir, depend, includes, install, lint, and tags.  For all of
466the directories listed in the variable SUBDIR, the specified directory 
467will be visited and the target made.  There is also a default target which
468allows the command "make subdir" where subdir is any directory listed in
469the variable SUBDIR.
470
471As a special case, the use of a token .WAIT as an entry in SUBDIR acts
472as a synchronization barrier when multiple make jobs are run; subdirs
473before the .WAIT must complete before any subdirs after .WAIT are
474started.  See make(1) for some caveats on use of .WAIT and other
475special sources.
476
477=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
478
479The include file <bsd.links.mk> handles the LINKS and SYMLINKS variables
480and is included from from bsd.lib.mk and bsd.prog.mk.
481
482=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
483
484The include file <bsd.files.mk> handles the FILES variables and is included
485from bsd.lib.mk and bsd.prog.mk.
486
487=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
488
489The include file <bsd.inc.mk> defines the includes target and uses two
490variables:
491
492INCS	The list of include files
493
494INCSDIR	The location to install the include files.
495
496=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
497
498The include file <bsd.kinc.mk> defines the many targets (includes,
499subdirectories, etc.), and is used by kernel makefiles to handle
500include file installation.  It is intended to be included alone, by
501kernel Makefiles.  Please see bsd.kinc.mk for more details, and keep
502the documentation in that file up to date.
503
504=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
505
506The include file <bsd.info.mk> is used to generate and install GNU Info
507documentation from respective Texinfo source files.  It defines three
508implicit targets (.txi.info, .texi.info, and .texinfo.info), and uses the
509following variables:
510
511TEXINFO		List of Texinfo source files.  Info documentation will
512		consist of single files with the extension replaced by
513		.info.
514
515INFOFLAGS	Flags to pass to makeinfo.  []
516
517INSTALL_INFO	Name of install-info program.  [install-info]
518
519MAKEINFO	Name of makeinfo program.  [makeinfo]
520
521=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
522
523The include file <bsd.sys.mk> is used by <bsd.prog.mk> and
524<bsd.lib.mk>.  It contains overrides that are used when building
525the NetBSD source tree.  For instance, if "PARALLEL" is defined by
526the program/library Makefile, it includes a set of rules for lex and
527yacc that allow multiple lex and yacc targets to be built in parallel.
528
529Other variables of note (incomplete list):
530
531WARNS		Crank up gcc warning options; WARNS=1 and WARNS=2 are the two
532		distinct levels.
533
534FORMAT_AUDIT	If FORMAT_AUDIT is set, and WFORMAT is set and > 1, turn on
535WFORMAT 	-Wnetbsd-format-audit for extra-stringent format checking.
536		WFORMAT belongs in individual makefiles and/or
537		Makefile.inc files.  (set WFORMAT=1 in individual
538		makefiles if a program is not security critical and is
539		doing bizarre things with format strings which would
540		be even uglier if rewritten) FORMAT_AUDIT should go in
541		mk.conf if you're doing format-string auditing. 
542		FORMAT_AUDIT may go away in time.
543
544=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
545
546The include file <bsd.lib.mk> has support for building libraries.  It has
547the same eight targets as <bsd.prog.mk>: all, clean, cleandir, depend,
548includes, install, lint, and tags.  Additionally, it has a checkver target
549which checks for installed shared object libraries whose version is greater
550that the version of the source. It has a limited number of suffixes,
551consistent with the current needs of the BSD tree.
552
553It sets/uses the following variables:
554
555LIB		The name of the library to build.
556
557LIBDIR		Target directory for libraries.
558
559LINTLIBDIR	Target directory for lint libraries.
560
561LIBGRP		Library group.
562
563LIBOWN		Library owner.
564
565LIBMODE		Library mode.
566
567LDADD		Additional loader objects.
568
569MAN		The manual pages to be installed (use a .1 - .9 suffix).
570
571MKLINKLIB	If "no", act as "MKPICINSTALL=no MKPROFILE=no".
572		Also:
573			- don't install the .a libraries
574			- don't install _pic.a libraries on PIC systems
575			- don't build .a libraries on PIC systems
576			- don't install the .so symlink on ELF systems
577		I.e, only install the shared library (and the .so.major
578		symlink on ELF).
579
580MKPICLIB	If "no", don't build _pic.a libraries, and build the
581		shared object libraries from the .a libraries.  A
582		symlink is installed in ${DESTDIR}/usr/lib for the
583		_pic.a library pointing to the .a library.
584
585NOCHECKVER_<library>
586NOCHECKVER	If set, disables checking for installed shared object
587		libraries with versions greater than the source.  A
588		particular library name, without the "lib" prefix, may
589		be appended to the variable name to disable the check for
590		only that library.
591
592SRCS		List of source files to build the library.  Suffix types
593		.s, .c, and .f are supported.  Note, .s files are preferred
594		to .c files of the same name.  (This is not the default for
595		versions of make.)
596
597The include file <bsd.lib.mk> includes the file named "../Makefile.inc"
598if it exists, as well as the include file <bsd.man.mk>.
599
600It has rules for building profiled objects; profiled libraries are
601built by default.
602
603Libraries are ranlib'd when made.
604
605=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
606
607The include file <bsd.obj.mk> defines targets related to the creation
608and use of separated object and source directories.
609
610If an environment variable named MAKEOBJDIRPREFIX is set, make(1) uses
611${MAKEOBJDIRPREFIX}${.CURDIR} as the name of the object directory if
612it exists.  Otherwise make(1) looks for the existence of a
613subdirectory (or a symlink to a directory) of the source directory
614into which built targets should be placed.  If an environment variable
615named MAKEOBJDIR is set, make(1) uses its value as the name of the
616object directory; failing that, make first looks for a subdirectory
617named "obj.${MACHINE}", and if that doesn't exist, it looks for "obj".
618
619Object directories are not created automatically by make(1) if they
620don't exist; you need to run a separate "make obj".  (This will happen
621during a top-level build if "MKOBJDIRS" is set to a value other than
622"no").  When the source directory is a subdirectory of ${BSDSRCDIR} --
623and this is determined by a simple string prefix comparison -- object
624directories are created in a separate object directory tree, and a
625symlink to the object directory in that tree is created in the source
626directory; otherwise, "make obj" assumes that you're not in the main
627source tree and that it's not safe to use a separate object tree.
628
629Several variables used by <bsd.obj.mk> control exactly what
630directories and links get created during a "make obj":
631
632MAKEOBJDIR	If set, this is the component name of the object
633		directory.
634
635OBJMACHINE	If this is set but MAKEOBJDIR is not set, creates
636		object directories or links named "obj.${MACHINE}";
637		otherwise, just creates ones named "obj".
638
639USR_OBJMACHINE  If set, and the current directory is a subdirectory of
640		${BSDSRCDIR}, create object directory in the
641		corresponding subdirectory of ${BSDOBJDIR}.${MACHINE};
642		otherwise, create it in the corresponding subdirectory
643		of ${BSDOBJDIR}
644
645=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
646
647The include file <bsd.kernobj.mk> defines variables related to the
648location of kernel sources and object directories.
649
650KERNSRCDIR	Is the location of the top of the kernel src.
651		It defaults to ${BSDSRCDIR}/sys, but the top-level
652		Makefile.inc sets it to ${ABSTOP}/sys (ABSTOP is the
653		absolute path to the directory where the top-level
654		Makefile.inc was found.
655
656KERNARCHDIR	Is the location of the machine dependent kernel
657		sources.  It defaults to arch/${MACHINE}
658		
659KERNCONFDIR	Is where the configuration files for kernels are
660		found; default is ${KERNSRCDIR}/${KERNARCHDIR}/conf.
661
662KERNOBJDIR	Is the kernel build directory.  The kernel GENERIC for
663		instance will be compiled in ${KERNOBJDIR}/GENERIC.
664		The default value is
665		${MAKEOBJDIRPREFIX}${KERNSRCDIR}/${KERNARCHDIR}/compile
666		if it exists or the target 'obj' is being made.
667		Otherwise the default is
668		${KERNSRCDIR}/${KERNARCHDIR}/compile.
669
670It is important that Makefiles (such as those under src/distrib) that
671wish to find compiled kernels use bsd.kernobj.mk and ${KERNOBJDIR}
672rather than make assumptions about the location of the compiled kernel.
673
674=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
675