bsd.README revision 1.71
1#	$NetBSD: bsd.README,v 1.71 2000/12/30 04:11:34 itojun 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 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.
91
92MKOBJ		If "no", don't enable the rule which creates objdirs.
93		"yes" by default.
94
95MKOBJDIRS	If "no", don't create objdirs during a "make build".
96		"no" by default.
97
98MKPIC		If "no", don't build or install shared libraries.
99
100MKPICINSTALL	If "no", don't install the *_pic.a libraries.
101
102MKPROFILE	If "no", don't build or install the profiling libraries.
103
104MKSHARE		If "no", act as "MKCATPAGES=no MKDOC=no MKINFO=no MKMAN=no
105		MKNLS=no".  I.e, don't build catman pages, documentation,
106		Info documentation, man pages, NLS files, ...
107
108=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
109
110The include file <sys.mk> has the default rules for all makes, in the BSD
111environment or otherwise.  You probably don't want to touch this file.
112If you intend to run a cross build, you will need to supply the following
113host tools, and configure the following variables properly:
114
115OBJCOPY		objcopy - copy and translate object files
116
117STRIP		strip - Discard symbols from object files
118
119CONFIG		config - build kernel compilation directories
120
121RPCGEN		rpcgen - Remote Procedure Call (RPC) protocol compiler
122
123MKLOCALE	mklocale - make LC_CTYPE locale files
124
125=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
126
127The include file <bsd.man.mk> handles installing manual pages and their
128links.
129
130It has a two targets:
131
132	maninstall:
133		Install the manual page sources and their links.
134	catinstall:
135		Install the preformatted manual pages and their links.
136
137It sets/uses the following variables:
138
139MANDIR		Base path for manual installation.
140
141MANGRP		Manual group.
142
143MANOWN		Manual owner.
144
145MANMODE		Manual mode.
146
147MANSUBDIR	Subdirectory under the manual page section, i.e. "/vax"
148		or "/tahoe" for machine specific manual pages.
149
150MAN		The manual pages to be installed (use a .1 - .9 suffix).
151
152MLINKS		List of manual page links (using a .1 - .9 suffix).  The
153		linked-to file must come first, the linked file second,
154		and there may be multiple pairs.  The files are soft-linked.
155
156The include file <bsd.man.mk> includes a file named "../Makefile.inc" if
157it exists.
158
159=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
160
161The include file <bsd.own.mk> contains source tree configuration parameters,
162such as the owners, groups, etc. for both manual pages and binaries, and
163a few global "feature configuration" parameters.
164
165It has no targets.
166
167To get system-specific configuration parameters, bsd.own.mk will try to
168include the file specified by the "MAKECONF" variable.  If MAKECONF is not
169set, or no such file exists, the system make configuration file, /etc/mk.conf
170is included.  These files may define any of the variables described below.
171
172bsd.own.mk sets the following variables, if they are not already defined
173(defaults are in brackets):
174
175BSDSRCDIR	The real path to the system sources, so that 'make obj'
176		will work correctly. [/usr/src]
177
178BSDOBJDIR	The real path to the system 'obj' tree, so that 'make obj'
179		will work correctly. [/usr/obj]
180
181BINGRP		Binary group. [wheel]
182
183BINOWN		Binary owner. [root]
184
185BINMODE		Binary mode. [555]
186
187NONBINMODE	Mode for non-executable files. [444]
188
189MANDIR		Base path for manual installation. [/usr/share/man/cat]
190
191MANGRP		Manual group. [wheel]
192
193MANOWN		Manual owner. [root]
194
195MANMODE		Manual mode. [${NONBINMODE}]
196
197MANINSTALL	Manual installation type: maninstall, catinstall, or both
198
199LIBDIR		Base path for library installation. [/usr/lib]
200
201LINTLIBDIR	Base path for lint(1) library installation. [/usr/libdata/lint]
202
203LIBGRP		Library group. [${BINGRP}]
204
205LIBOWN		Library owner. [${BINOWN}]
206
207LIBMODE		Library mode. [${NONBINMODE}]
208
209DOCDIR		Base path for system documentation (e.g. PSD, USD, etc.)
210	        installation. [/usr/share/doc]
211
212HTMLDOCDIR	Base path for html system documentation installation.
213		[/usr/share/doc/html]
214
215DOCGRP		Documentation group. [wheel]
216
217DOCOWN		Documentation owner. [root]
218
219DOCMODE		Documentation mode. [${NONBINMODE}]
220
221NLSDIR		Base path for National Language Support files installation.
222		[/usr/share/nls]
223
224NLSGRP		National Language Support files group. [wheel]
225
226NLSOWN		National Language Support files owner. [root]
227
228NLSMODE		National Language Support files mode. [${NONBINMODE}]
229
230STRIPFLAG	The flag passed to the install program to cause the binary
231		to be stripped.  This is to be used when building your
232		own install script so that the entire system can be made
233		stripped/not-stripped using a single knob. [-s]
234
235COPY		The flag passed to the install program to cause the binary
236		to be copied rather than moved.  This is to be used when
237		building our own install script so that the entire system
238		can either be installed with copies, or with moves using
239		a single knob. [-c]
240
241Additionally, the following variables may be set by bsd.own.mk or in a
242make configuration file to modify the behaviour of the system build
243process (default values are in brackets along with comments, if set by
244bsd.own.mk):
245
246MKCRYPTO	If set to "no", no cryptography support will be built
247		into the system.  Defaults to "yes".
248
249NOCRYPTO	If set, it is equivalent to setting MKCRYPTO to "no".
250
251MKCRYPTO_IDEA	If set to "yes", IDEA support will be built into
252		libcrypto_idea.a.  Defaults to "no".
253
254MKCRYPTO_RC5	If set to "yes", RC5 support will be built into
255		libcrypto_rc5.a.  Defaults to "no".
256
257MKKERBEROS	If set to "no", disables building Kerberos (v4 or v5)
258		support into various system utilities that support it.
259		Defaults to "yes".  NOTE: This does not affect the
260		building of the Kerberos libraries or infrastructure
261		programs themselves.  To completely disable Kerberos,
262		set MKCRYPTO to "no".
263
264NOKERBEROS	If set, it is equivalent to setting MKKERBEROS to "no".
265
266SKEY		Compile in support for S/key authentication. [yes, set
267		unconditionally]
268
269MANZ		Compress manual pages at installation time.
270
271SYS_INCLUDE	Copy or symlink kernel include files into /usr/include.
272		Possible values are "symlinks" or "copies" (which is
273		the same as the variable being unset).
274
275NOPROFILE	Do not build profiled versions of system libraries
276
277NOPIC		Do not build PIC versions of system libraries, and
278		do not build shared libraries.  [set if ${MACHINE_ARCH}
279		is "sh3" and ${OBJECT_FMT} is "COFF", unset otherwise.]
280
281NOLINT		Do not build lint libraries.
282
283OBJECT_FMT	Object file format. [set to "ELF" on architectures that
284		use ELF -- currently if ${MACHINE_ARCH} is "alpha",
285		"mipsel", "mipseb", "powerpc", "sparc", "sparc64",
286		and "i386", or set to "a.out" on other architectures].
287
288
289bsd.own.mk is generally useful when building your own Makefiles so that
290they use the same default owners etc. as the rest of the tree.
291
292=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
293
294The include file <bsd.prog.mk> handles building programs from one or
295more source files, along with their manual pages.  It has a limited number
296of suffixes, consistent with the current needs of the BSD tree.
297
298It has eight targets:
299
300	all:
301		build the program and its manual page
302	clean:
303		remove the program, any object files and the files a.out,
304		Errs, errs, mklog, and ${PROG}.core.
305	cleandir:
306		remove all of the files removed by the target clean, as
307		well as .depend, tags, and any manual pages.
308		`distclean' is a synonym for `cleandir'.
309	depend:
310		make the dependencies for the source files, and store
311		them in the file .depend.
312	includes:
313		install any header files.
314	install:
315		install the program and its manual pages; if the Makefile
316		does not itself define the target install, the targets
317		beforeinstall and afterinstall may also be used to cause
318		actions immediately before and after the install target
319		is executed.
320	lint:
321		run lint on the source files
322	tags:
323		create a tags file for the source files.
324
325It sets/uses the following variables:
326
327BINGRP		Binary group.
328
329BINOWN		Binary owner.
330
331BINMODE		Binary mode.
332
333CLEANFILES	Additional files to remove for the clean and cleandir targets.
334
335COPTS		Additional flags to the compiler when creating C objects.
336
337CPPFLAGS	Additional flags to the C pre-processor
338
339LDADD		Additional loader objects.  Usually used for libraries.
340		For example, to load with the compatibility and utility
341		libraries, use:
342
343			LDADD+=-lutil -lcompat
344
345LDFLAGS		Additional loader flags.
346
347LINKS		The list of binary links; should be full pathnames, the
348		linked-to file coming first, followed by the linked
349		file.  The files are hard-linked.  For example, to link
350		/bin/test and /bin/[, use:
351
352			LINKS=	${DESTDIR}/bin/test ${DESTDIR}/bin/[
353
354SYMLINKS	The list of symbolic links; should be full pathnames.
355                Syntax is identical to LINKS. Note that DESTDIR is not
356		automatically included in the link.
357
358MAN		Manual pages (should end in .1 - .9).  If no MAN variable is
359		defined, "MAN=${PROG}.1" is assumed.
360
361PROG		The name of the program to build.  If not supplied, nothing
362		is built.
363
364PROGNAME	The name that the above program will be installed as, if
365		different from ${PROG}.
366
367SRCS		List of source files to build the program.  If SRCS is not
368		defined, it's assumed to be ${PROG}.c.
369
370DPADD		Additional dependencies for the program.  Usually used for
371		libraries.  For example, to depend on the compatibility and
372		utility libraries use:
373
374			DPADD+=${LIBCOMPAT} ${LIBUTIL}
375
376		The following libraries are predefined for DPADD:
377
378		LIBCRT0?=	${DESTDIR}/usr/lib/crt0.o
379		LIBC?=		${DESTDIR}/usr/lib/libc.a
380		LIBC_PIC?=	${DESTDIR}/usr/lib/libc_pic.a
381		LIBCOMPAT?=	${DESTDIR}/usr/lib/libcompat.a
382		LIBCRYPT?=	${DESTDIR}/usr/lib/libcrypt.a
383		LIBCURSES?=	${DESTDIR}/usr/lib/libcurses.a
384		LIBDBM?=	${DESTDIR}/usr/lib/libdbm.a
385		LIBDES?=	${DESTDIR}/usr/lib/libdes.a
386		LIBEDIT?=	${DESTDIR}/usr/lib/libedit.a
387		LIBGCC?=	${DESTDIR}/usr/lib/libgcc.a
388		LIBGNUMALLOC?=	${DESTDIR}/usr/lib/libgnumalloc.a
389		LIBINTL?=	${DESTDIR}/usr/lib/libintl.a
390		LIBIPSEC?=	${DESTDIR}/usr/lib/libipsec.a
391		LIBKDB?=	${DESTDIR}/usr/lib/libkdb.a
392		LIBKRB?=	${DESTDIR}/usr/lib/libkrb.a
393		LIBKVM?=	${DESTDIR}/usr/lib/libkvm.a
394		LIBL?=		${DESTDIR}/usr/lib/libl.a
395		LIBM?=		${DESTDIR}/usr/lib/libm.a
396		LIBMENU?=	${DESTDIR}/usr/lib/libmenu.a
397		LIBMP?=		${DESTDIR}/usr/lib/libmp.a
398		LIBNTP?=	${DESTDIR}/usr/lib/libntp.a
399		LIBPC?=		${DESTDIR}/usr/lib/libpc.a
400		LIBPCAP?=	${DESTDIR}/usr/lib/libpcap.a
401		LIBPLOT?=	${DESTDIR}/usr/lib/libplot.a
402		LIBPOSIX?=	${DESTDIR}/usr/lib/libposix.a
403		LIBRESOLV?=	${DESTDIR}/usr/lib/libresolv.a
404		LIBRPCSVC?=	${DESTDIR}/usr/lib/librpcsvc.a
405		LIBSKEY?=	${DESTDIR}/usr/lib/libskey.a
406		LIBTERMCAP?=	${DESTDIR}/usr/lib/libtermcap.a
407		LIBTELNET?=	${DESTDIR}/usr/lib/libtelnet.a
408		LIBUTIL?=	${DESTDIR}/usr/lib/libutil.a
409		LIBWRAP?=	${DESTDIR}/usr/lib/libwrap.a
410		LIBY?=		${DESTDIR}/usr/lib/liby.a
411		LIBZ?=		${DESTDIR}/usr/lib/libz.a
412
413
414SHAREDSTRINGS	If defined, a new .c.o rule is used that results in shared
415		strings, using xstr(1). Note that this will not work with
416		parallel makes.
417
418STRIPFLAG	The flag passed to the install program to cause the binary
419		to be stripped.
420
421SUBDIR		A list of subdirectories that should be built as well.
422		Each of the targets will execute the same target in the
423		subdirectories.
424
425SCRIPTS		A list of interpreter scripts [file.{sh,csh,pl,awk,...}].
426		These are installed exactly like programs.
427
428SCRIPTSNAME	The name that the above program will be installed as, if
429		different from ${SCRIPTS}. These can be further specialized
430		by setting SCRIPTSNAME_<script>.
431
432FILES		A list of files to install. The installation is controlled
433		by the FILESNAME, FILESOWN, FILESGRP, FILESMODE, FILESDIR
434		variables that can be further specialized by FILES<VAR>_<file>
435
436The include file <bsd.prog.mk> includes the file named "../Makefile.inc"
437if it exists, as well as the include file <bsd.man.mk>.
438
439Some simple examples:
440
441To build foo from foo.c with a manual page foo.1, use:
442
443	PROG=	foo
444
445	.include <bsd.prog.mk>
446
447To build foo from foo.c with a manual page foo.2, add the line:
448
449	MAN=	foo.2
450
451If foo does not have a manual page at all, add the line:
452
453	NOMAN=	noman
454
455If foo has multiple source files, add the line:
456
457	SRCS=	a.c b.c c.c d.c
458
459=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
460
461The include file <bsd.subdir.mk> contains the default targets for building
462subdirectories.  It has the same eight targets as <bsd.prog.mk>: all, 
463clean, cleandir, depend, includes, install, lint, and tags.  For all of
464the directories listed in the variable SUBDIRS, the specified directory 
465will be visited and the target made.  There is also a default target which
466allows the command "make subdir" where subdir is any directory listed in
467the variable SUBDIRS.
468
469=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
470
471The include file <bsd.links.mk> handles the LINKS and SYMLINKS variables
472and is included from from bsd.lib.mk and bsd.prog.mk.
473
474=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
475
476The include file <bsd.files.mk> handles the FILES variables and is included
477from bsd.lib.mk and bsd.prog.mk.
478
479=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
480
481The include file <bsd.inc.mk> defines the includes target and uses two
482variables:
483
484INCS	The list of include files
485
486INCSDIR	The location to install the include files.
487
488=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
489
490The include file <bsd.kinc.mk> defines the many targets (includes,
491subdirectories, etc.), and is used by kernel makefiles to handle
492include file installation.  It is intended to be included alone, by
493kernel Makefiles.  Please see bsd.kinc.mk for more details, and keep
494the documentation in that file up to date.
495
496=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
497
498The include file <bsd.info.mk> is used to generate and install GNU Info
499documentation from respective Texinfo source files.  It defines three
500implicit targets (.txi.info, .texi.info, and .texinfo.info), and uses the
501following variables:
502
503TEXINFO		List of Texinfo source files.  Info documentation will
504		consist of single files with the extension replaced by
505		.info.
506
507INFOFLAGS	Flags to pass to makeinfo.  []
508
509INSTALL_INFO	Name of install-info program.  [install-info]
510
511MAKEINFO	Name of makeinfo program.  [makeinfo]
512
513=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
514
515The include file <bsd.sys.mk> is used by <bsd.prog.mk> and
516<bsd.lib.mk>.  It contains overrides that are used when building
517the NetBSD source tree.  For instance, if "PARALLEL" is defined by
518the program/library Makefile, it includes a set of rules for lex and
519yacc that allow multiple lex and yacc targets to be built in parallel.
520
521Other variables of note (incomplete list):
522
523WARNS		Crank up gcc warning options; WARNS=1 and WARNS=2 are the two
524		distinct levels.
525
526FORMAT_AUDIT	If FORMAT_AUDIT is set, and WFORMAT is set and > 1, turn on
527WFORMAT 	-Wnetbsd-format-audit for extra-stringent format checking.
528		WFORMAT belongs in individual makefiles and/or Makefile.inc files.
529		(set WFORMAT=1 in individual makefiles if a program is
530		not security critical and is doing bizarre things with
531		format strings which would be even uglier if rewritten)
532		FORMAT_AUDIT should go in mk.conf if you're doing format-string auditing.
533		FORMAT_AUDIT may go away in time.
534
535=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
536
537The include file <bsd.lib.mk> has support for building libraries.  It has
538the same eight targets as <bsd.prog.mk>: all, clean, cleandir, depend,
539includes, install, lint, and tags.  Additionally, it has a checkver target
540which checks for installed shared object libraries whose version is greater
541that the version of the source. It has a limited number of suffixes,
542consistent with the current needs of the BSD tree.
543
544It sets/uses the following variables:
545
546LIB		The name of the library to build.
547
548LIBDIR		Target directory for libraries.
549
550LINTLIBDIR	Target directory for lint libraries.
551
552LIBGRP		Library group.
553
554LIBOWN		Library owner.
555
556LIBMODE		Library mode.
557
558LDADD		Additional loader objects.
559
560MAN		The manual pages to be installed (use a .1 - .9 suffix).
561
562MKLINKLIB	If "no", act as "MKPICINSTALL=no MKPROFILE=no".
563		Also:
564			- don't install the .a libraries
565			- don't install _pic.a libraries on PIC systems
566			- don't build .a libraries on PIC systems
567			- don't install the .so symlink on ELF systems
568		I.e, only install the shared library (and the .so.major
569		symlink on ELF).
570
571MKPICLIB	If "no", don't build _pic.a libraries, and build the
572		shared object libraries from the .a libraries.  A
573		symlink is installed in ${DESTDIR}/usr/lib for the
574		_pic.a library pointing to the .a library.
575
576NOCHECKVER_<library>
577NOCHECKVER	If set, disables checking for installed shared object
578		libraries with versions greater than the source.  A
579		particular library name, without the "lib" prefix, may
580		be appended to the variable name to disable the check for
581		only that library.
582
583SRCS		List of source files to build the library.  Suffix types
584		.s, .c, and .f are supported.  Note, .s files are preferred
585		to .c files of the same name.  (This is not the default for
586		versions of make.)
587
588The include file <bsd.lib.mk> includes the file named "../Makefile.inc"
589if it exists, as well as the include file <bsd.man.mk>.
590
591It has rules for building profiled objects; profiled libraries are
592built by default.
593
594Libraries are ranlib'd when made.
595
596=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
597
598The include file <bsd.obj.mk> defines targets related to the creation
599and use of separated object and source directories.
600
601If an environment variable named MAKEOBJDIRPREFIX is set, make(1) uses
602${MAKEOBJDIRPREFIX}${.CURDIR} as the name of the object directory if
603it exists.  Otherwise make(1) looks for the existance of a
604subdirectory (or a symlink to a directory) of the source directory
605into which built targets should be placed.  If an environment variable
606named MAKEOBJDIR is set, make(1) uses its value as the name of the
607object directory; failing that, make first looks for a subdirectory
608named "obj.${MACHINE}", and if that doesn't exist, it looks for "obj".
609
610Object directories are not created automatically by make(1) if they
611don't exist; you need to run a separate "make obj".  (This will happen
612during a top-level build if "MKOBJDIRS" is set to a value other than
613"no").  When the source directory is a subdirectory of ${BSDSRCDIR} --
614and this is determined by a simple string prefix comparison -- object
615directories are created in a separate object directory tree, and a
616symlink to the object directory in that tree is created in the source
617directory; otherwise, "make obj" assumes that you're not in the main
618source tree and that it's not safe to use a separate object tree.
619
620Several variables used by <bsd.obj.mk> control exactly what
621directories and links get created during a "make obj":
622
623MAKEOBJDIR	If set, this is the component name of the object
624		directory.
625
626OBJMACHINE	If this is set but MAKEOBJDIR is not set, creates
627		object directories or links named "obj.${MACHINE}";
628		otherwise, just creates ones named "obj".
629
630USR_OBJMACHINE  If set, and the current directory is a subdirectory of
631		${BSDSRCDIR}, create object directory in the
632		corresponding subdirectory of ${BSDOBJDIR}.${MACHINE};
633		otherwise, create it in the corresponding subdirectory
634		of ${BSDOBJDIR}
635
636=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
637
638The include file <bsd.kernobj.mk> defines variables related to the
639location of kernel sources and object directories.
640
641KERNSRCDIR	Is the location of the top of the kernel src.
642		It defaults to ${BSDSRCDIR}/sys, but the top-level
643		Makefile.inc sets it to ${ABSTOP}/sys (ABSTOP is the
644		absolute path to the directory where the top-level
645		Makefile.inc was found.
646
647KERNARCHDIR	Is the location of the machine dependent kernel
648		sources.  It defaults to arch/${MACHINE}
649		
650KERNCONFDIR	Is where the configuration files for kernels are
651		found; default is ${KERNSRCDIR}/${KERNARCHDIR}/conf.
652
653KERNOBJDIR	Is the kernel build directory.  The kernel GENERIC for
654		instance will be compiled in ${KERNOBJDIR}/GENERIC.
655		The default value is
656		${MAKEOBJDIRPREFIX}${KERNSRCDIR}/${KERNARCHDIR}/compile
657		if it exists or the target 'obj' is being made.
658		Otherwise the default is
659		${KERNSRCDIR}/${KERNARCHDIR}/compile.
660
661It is important that Makefiles (such as those under src/distrib) that
662wish to find compiled kernels use bsd.kernobj.mk and ${KERNOBJDIR}
663rather than make assumptions about the location of the compiled kernel.
664
665=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
666