xref: /freebsd/share/mk/bsd.README (revision d93a896e)
1#	@(#)bsd.README	8.2 (Berkeley) 4/2/94
2# $FreeBSD$
3
4This is the README file for the "include" files for the FreeBSD
5source tree.  The files are installed in /usr/share/mk, and are by
6convention, named with the suffix ".mk".  These files store several
7build options and should be handled with caution.
8
9Note, this file is not intended to replace reading through the .mk
10files for anything tricky.
11
12There are two main types of make include files.  One type is the generally
13usable make include files, such as bsd.prog.mk and bsd.lib.mk.  The other is
14the internal make include files, such as bsd.files.mk and bsd.man.mk, which
15can not/should not be used directly but are used by the other make include
16files.  In most cases it is only interesting to include bsd.prog.mk or
17bsd.lib.mk.
18
19bsd.arch.inc.mk		- includes arch-specific Makefile.$arch
20bsd.compiler.mk		- defined based on current compiler
21bsd.confs.mk		- install of configuration files
22bsd.cpu.mk		- sets CPU/arch-related variables (included from sys.mk)
23bsd.crunchgen.mk	- building crunched binaries using crunchgen(1)
24bsd.dep.mk		- handle Makefile dependencies
25bsd.doc.mk		- building troff system documents
26bsd.endian.mk		- TARGET_ENDIAN=1234(little) or 4321 (big) for target
27bsd.files.mk		- install of general purpose files
28bsd.incs.mk		- install of include files
29bsd.info.mk		- building GNU Info hypertext system (deprecated)
30bsd.init.mk		- initialization for the make include files
31bsd.kmod.mk		- building loadable kernel modules
32bsd.lib.mk		- support for building libraries
33bsd.libnames.mk		- define library names
34bsd.links.mk		- install of links (sym/hard)
35bsd.man.mk		- install of manual pages and their links
36bsd.nls.mk		- build and install of NLS catalogs
37bsd.obj.mk		- creating 'obj' directories and cleaning up
38bsd.own.mk		- define common variables
39bsd.port.mk		- building ports
40bsd.port.post.mk	- building ports
41bsd.port.pre.mk		- building ports
42bsd.port.subdir.mk	- targets for building subdirectories for ports
43bsd.prog.mk		- building programs from source files
44bsd.progs.mk		- build multiple programs from sources
45bsd.snmpmod.mk		- building modules for the SNMP daemon bsnmpd
46bsd.subdir.mk		- targets for building subdirectories
47bsd.sys.mk		- common settings used for building FreeBSD sources
48bsd.test.mk		- building test programs from source files
49sys.mk			- default rules for all makes
50
51This file does not document bsd.port*.mk.  They are documented in ports(7).
52
53See also make(1), mkdep(1), style.Makefile(5) and `PMake - A
54Tutorial', located in /usr/share/doc/psd/12.make.
55
56=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
57
58Random things worth knowing about this document:
59
60If appropriate when documenting the variables the default value is
61indicated using square brackets e.g. [gzip].
62In some cases the default value depend on other values (e.g. system
63architecture).  In these cases the most common value is indicated.
64
65This document contains some simple examples of the usage of the BSD make
66include files.  For more examples look at the makefiles in the FreeBSD
67source tree.
68
69=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
70
71RANDOM THINGS WORTH KNOWING:
72
73The files are like C-style #include files, and pretty much behave like
74you'd expect.  The syntax is slightly different in that a single '.' is
75used instead of the hash mark, i.e. ".include <bsd.prog.mk>".
76
77One difference that will save you lots of debugging time is that inclusion
78of the file is normally done at the *end* of the Makefile.  The reason for
79this is because .mk files often modify variables and behavior based on the
80values of variables set in the Makefile.  To make this work, remember that
81the FIRST target found is the target that is used, i.e. if the Makefile has:
82
83	a:
84		echo a
85	a:
86		echo a number two
87
88the command "make a" will echo "a".  To make things confusing, the SECOND
89variable assignment is the overriding one, i.e. if the Makefile has:
90
91	a=	foo
92	a=	bar
93
94	b:
95		echo ${a}
96
97the command "make b" will echo "bar".  This is for compatibility with the
98way the V7 make behaved.
99
100It's fairly difficult to make the BSD .mk files work when you're building
101multiple programs in a single directory.  It's a lot easier to split up
102the programs than to deal with the problem.  Most of the agony comes from
103making the "obj" directory stuff work right, not because we switch to a new
104version of make.  So, don't get mad at us, figure out a better way to handle
105multiple architectures so we can quit using the symbolic link stuff.
106(Imake doesn't count.)
107
108The file .depend in the source directory is expected to contain dependencies
109for the source files.  This file is read automatically by make after reading
110the Makefile.
111
112The variable DESTDIR works as before.  It's not set anywhere but will change
113the tree where the file gets installed.
114
115The profiled libraries are no longer built in a different directory than
116the regular libraries.  A new suffix, ".po", is used to denote a profiled
117object, and ".pico" denotes a position-independent relocatable object.
118
119=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
120
121The following variables are common:
122
123AFLAGS.${SRC}
124		Flags dependent on source file name.
125ACFLAGS.${SRC}
126		Flags dependent on source file name.
127CFLAGS.${SRC}
128		Flags dependent on source file name.
129CFLAGS.${COMPILER_TYPE}
130		Flags dependent on compiler added to CFLAGS.
131CFLAGS.${MACHINE_ARCH}
132		Architectural flags added to CFLAGS.
133CFLAGS_NO_SIMD	Add this to CFLAGS for programs that don't want any SIMD
134		instructions generated. It is setup in bsd.cpu.mk to an
135		appropriate value for the compiler and target.
136CXXFLAGS.${COMPILER_TYPE}
137		Flags dependent on compiler added to CXXFLAGS.
138CXXFLAGS.${MACHINE_ARCH}
139		Architectural flags added to CXXFLAGS.
140CXXFLAGS.${SRC}
141		Flags dependent on source file name.
142COMPILER_FEATURES
143		A list of features that the compiler supports. Zero or
144		more of:
145			c++11	Supports full C++ 11 standard.
146
147COMPILER_TYPE	Type of compiler, either clang or gcc, though other
148		values are possible. Don't assume != clang == gcc.
149
150COMPILER_VERSION
151		A numeric constant equal to:
152		     major * 10000 + minor * 100 + tiny
153		for the compiler's self-reported version.
154
155=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
156
157The include file <sys.mk> has the default rules for all makes, in the BSD
158environment or otherwise.  You probably don't want to touch this file.
159
160=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
161
162The include file <bsd.arch.inc.mk> includes other Makefiles for specific
163architectures, if they exist. It will include the first of the following
164files that it finds: Makefile.${MACHINE}, Makefile.${MACHINE_ARCH},
165Makefile.${MACHINE_CPUARCH}
166
167=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
168
169The include file <bsd.man.mk> handles installing manual pages and their
170links.
171
172It has three targets:
173
174	all-man:
175		build manual pages.
176	maninstall:
177		install the manual pages and their links.
178	manlint:
179		verify the validity of manual pages.
180
181It sets/uses the following variables:
182
183MAN		The manual pages to be installed (use a .1 - .9 suffix).
184
185MANDIR		Base path for manual installation.
186
187MANGRP		Manual group.
188
189MANMODE		Manual mode.
190
191MANOWN		Manual owner.
192
193MANSUBDIR	Subdirectory under the manual page section, i.e. "/vax"
194		or "/tahoe" for machine specific manual pages.
195
196MLINKS		List of manual page links (using a .1 - .9 suffix).  The
197		linked-to file must come first, the linked file second,
198		and there may be multiple pairs.  The files are hard-linked.
199
200The include file <bsd.man.mk> includes a file named "../Makefile.inc" if
201it exists.
202
203=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
204
205The include file <bsd.own.mk> contains the owners, groups, etc. for both
206manual pages and binaries.
207
208It has no targets.
209
210It sets/uses the following variables:
211
212BINGRP		Binary group.
213
214BINMODE		Binary mode.
215
216BINOWN		Binary owner.
217
218MANDIR		Base path for manual installation.
219
220MANGRP		Manual group.
221
222MANMODE		Manual mode.
223
224MANOWN		Manual owner.
225
226This file is generally useful when building your own Makefiles so that
227they use the same default owners etc. as the rest of the tree.
228
229=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
230
231The include file <bsd.prog.mk> handles building programs from one or
232more source files, along with their manual pages.  It has a limited number
233of suffixes, consistent with the current needs of the BSD tree.
234
235It has seven targets:
236
237	all:
238		build the program and its manual page
239	clean:
240		remove the program and any object files.
241	cleandir:
242		remove all of the files removed by the target clean, as
243		well as .depend, tags, and any manual pages.
244	depend:
245		make the dependencies for the source files, and store
246		them in the file .depend.
247	install:
248		install the program and its manual pages; if the Makefile
249		does not itself define the target install, the targets
250		beforeinstall and afterinstall may also be used to cause
251		actions immediately before and after the install target
252		is executed.
253	lint:
254		run lint on the source files
255	tags:
256		create a tags file for the source files.
257
258It sets/uses the following variables:
259
260ACFLAGS		Flags to the compiler when preprocessing and
261		assembling .S files.
262
263AFLAGS		Flags to the assembler when assembling .s files.
264
265BINGRP		Binary group.
266
267BINMODE		Binary mode.
268
269BINOWN		Binary owner.
270
271CFLAGS		Flags to the compiler when creating C objects.
272
273CLEANDIRS	Additional files (CLEANFILES) and directories (CLEANDIRS) to
274CLEANFILES	remove during clean and cleandir targets.  "rm -rf" and
275		"rm -f" are used, respectively.
276
277DPADD		Additional dependencies for the program.  Usually used for
278		libraries.  For example, to depend on the compatibility and
279		utility libraries use:
280
281			DPADD=${LIBCOMPAT} ${LIBUTIL}
282
283		There is a predefined identifier for each (non-profiled,
284		non-shared) library and object.  Library file names are
285		transformed to identifiers by removing the extension and
286		converting to upper case.
287
288		There are no special identifiers for profiled or shared
289		libraries or objects.  The identifiers for the standard
290		libraries are used in DPADD.  This works correctly iff all
291		the libraries are built at the same time.  Unfortunately,
292		it causes unnecessary relinks to shared libraries when
293		only the static libraries have changed.  Dependencies on
294		shared libraries should be only on the library version
295		numbers.
296
297FILES		A list of non-executable files.
298		The installation is controlled by the FILESNAME, FILESOWN,
299		FILESGRP, FILESMODE, FILESDIR variables that can be
300		further specialized by FILES<VAR>_<file>.
301
302LDADD		Additional loader objects.  Usually used for libraries.
303		For example, to load with the compatibility and utility
304		libraries, use:
305
306			LDADD=-lutil -lcompat
307
308LDFLAGS		Additional loader flags. Passed to the loader via CC,
309		since that's used to link programs as well, so loader
310		specific flags need to be prefixed with -Wl, to work.
311
312LIBADD		Additional libraries.  This is for base system libraries
313		and is only valid inside of the /usr/src tree.
314		Use LIBADD=name instead of LDADD=-lname.
315
316LINKS		The list of binary links; should be full pathnames, the
317		linked-to file coming first, followed by the linked
318		file.  The files are hard-linked.  For example, to link
319		/bin/test and /bin/[, use:
320
321			LINKS=	/bin/test /bin/[
322
323MAN		Manual pages.  If no MAN variable is defined,
324		"MAN=${PROG}.1" is assumed. See bsd.man.mk for more details.
325
326PROG		The name of the program to build.  If not supplied, nothing
327		is built.
328
329PROGNAME	The name that the above program will be installed as, if
330		different from ${PROG}.
331
332PROG_CXX	If defined, the name of the program to build.  Also
333		causes <bsd.prog.mk> to link the program with the
334		standard C++ library.  PROG_CXX overrides the value
335		of PROG if PROG is also set.
336
337PROGS		When used with <bsd.progs.mk>, allow building multiple
338PROGS_CXX	PROG and PROG_CXX in one Makefile.  To define
339		individual variables for each program the VAR.prog
340		syntax should be used.  For example:
341
342		PROGS=		foo bar
343		SRCS.foo=	foo_src.c
344		LDADD.foo=	-lutil
345		SRCS.bar=	bar_src.c
346
347		The supported variables are:
348		- BINDIR
349		- BINGRP
350		- BINMODE
351		- BINOWN
352		- CFLAGS
353		- CXXFLAGS
354		- DEBUG_FLAGS
355		- DPADD
356		- DPSRCS
357		- INTERNALPROG (no installation)
358		- LDADD
359		- LDFLAGS
360		- LIBADD
361		- LINKS
362		- MAN
363		- MLINKS
364		- NO_WERROR
365		- PROGNAME
366		- SRCS
367		- STRIP
368		- WARNS
369
370SCRIPTS		A list of interpreter scripts [file.{sh,csh,pl,awk,...}].
371		The installation is controlled by the SCRIPTSNAME, SCRIPTSOWN,
372		SCRIPTSGRP, SCRIPTSMODE, SCRIPTSDIR variables that can be
373		further specialized by SCRIPTS<VAR>_<script>.
374
375SRCS		List of source files to build the program.  If SRCS is not
376		defined, it's assumed to be ${PROG}.c or, if PROG_CXX is
377		defined, ${PROG_CXX}.cc.
378
379STRIP		The flag passed to the install program to cause the binary
380		to be stripped.  This is to be used when building your
381		own install script so that the entire system can be made
382		stripped/not-stripped using a single nob.
383
384SUBDIR		A list of subdirectories that should be built as well.
385		Each of the targets will execute the same target in the
386		subdirectories.
387
388The include file <bsd.prog.mk> includes the file named "../Makefile.inc"
389if it exists, as well as the include file <bsd.man.mk>.
390
391Some simple examples:
392
393To build foo from foo.c with a manual page foo.1, use:
394
395	PROG=	foo
396
397	.include <bsd.prog.mk>
398
399To build foo from foo.c with a manual page foo.2, add the line:
400
401	MAN=	foo.2
402
403If foo does not have a manual page at all, add the line:
404
405	MAN=
406
407If foo has multiple source files, add the line:
408
409	SRCS=	a.c b.c c.c d.c
410
411=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
412
413The include file, <bsd.snmpmod.mk>, handles building MIB modules for bsnmpd
414from one or more source files, along with their manual pages.  It has a
415limited number of suffixes, consistent with the current needs of the BSD
416tree.
417
418bsd.snmpmod.mk leverages bsd.lib.mk for building MIB modules and
419bsd.files.mk for installing MIB description and definition files.
420
421It implements the following additional targets:
422
423	smilint:
424		execute smilint on the MIBs defined by BMIBS.
425
426		The net-mgmt/libsmi package must be installed before
427		executing this target. The net-mgmt/net-snmp package
428		should be installed as well to reduce false positives
429		from smilint.
430
431It sets/uses the following variables:
432
433BMIBS		The MIB definitions to install.
434
435BMIBSDIR	The directory where the MIB definitions are installed.
436		This defaults to `${SHAREDIR}/snmp/mibs`.
437
438DEFS		The MIB description files to install.
439
440DEFSDIR		The directory where MIB description files are installed.
441		This defaults to `${SHAREDIR}/snmp/defs`.
442
443EXTRAMIBDEFS	Extra MIB description files to use as input when
444		generating ${MOD}_oid.h and ${MOD}_tree.[ch].
445
446EXTRAMIBSYMS	Extra MIB definition files used only for extracting
447		symbols.
448
449		EXTRAMIBSYMS are useful when resolving inter-module
450		dependencies and are useful with files containing only
451		enum-definitions.
452
453		See ${MOD}_oid.h for more details.
454
455LOCALBASE	The package root where smilint and the net-snmp
456		definitions can be found
457
458MOD		The bsnmpd module name.
459
460SMILINT		smilint binary to use with the smilint make target.
461
462SMILINT_FLAGS	flags to pass to smilint.
463
464SMIPATH		A colon-separated directory path where MIBs definitions
465		can be found. See "SMIPATH" in smi_config for more
466		details.
467
468XSYM		MIB names to extract symbols for. See ${MOD}_oid.h for
469		more details.
470
471It generates the following files:
472
473${MOD}_tree.c	A source file and header which programmatically describes
474${MOD}_tree.h	the MIB (type, OID name, ACCESS attributes, etc).
475
476		The files are generated via "gensnmptree -p".
477
478		See gensnmptree(1) for more details.
479
480${MOD}_oid.h	A header which programmatically describes the MIB root and
481		MIB tables.
482
483		The files are generated via "gensnmptree -e".
484
485		See gensnmptree(1) for more details.
486
487=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
488
489The include file <bsd.subdir.mk> contains the default targets for building
490subdirectories.  It has the same seven targets as <bsd.prog.mk>: all, clean,
491cleandir, depend, install, lint, and tags.  For all of the directories
492listed in the variable SUBDIRS, the specified directory will be visited
493and the target made.  There is also a default target which allows the
494command "make subdir" where subdir is any directory listed in the variable
495SUBDIRS.
496
497=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
498
499The include file <bsd.lib.mk> has support for building libraries.  It has
500the same seven targets as <bsd.prog.mk>: all, clean, cleandir, depend,
501install, lint, and tags.  It has a limited number of suffixes, consistent
502with the current needs of the BSD tree.
503
504It sets/uses the following variables:
505
506LDADD		Additional loader objects.
507
508LIB		The name of the library to build.  Both a shared and static
509		library will be built.  NO_PIC can be set to only build a
510		static library.
511
512LIBADD		Additional libraries.  This is for base system libraries
513		and is only valid inside of the /usr/src tree.
514		Use LIBADD=name instead of LDADD=-lname.
515
516LIBDIR		Target directory for libraries.
517
518LIBGRP		Library group.
519
520LIBMODE		Library mode.
521
522LIBOWN		Library owner.
523
524LIBRARIES_ONLY	Do not build or install files other than the library.
525
526LIB_CXX		The name of the library to build. It also causes
527		<bsd.lib.mk> to link the library with the
528		standard C++ library.  LIB_CXX overrides the value
529		of LIB if LIB is also set.  Both a shared and static library
530		will be built.  NO_PIC can be set to only build a static
531		library.
532
533LINTLIBDIR	Target directory for lint libraries.
534
535MAN		The manual pages to be installed. See bsd.man.mk for more
536		details.
537
538SHLIB		Like LIB but only builds a shared library.
539
540SHLIB_CXX	Like LIB_CXX but only builds a shared library.
541
542SHLIB_LDSCRIPT	Template file to generate shared library linker script.
543		If not defined, a simple symlink is created to the real
544		shared object.
545
546SRCS		List of source files to build the library.  Suffix types
547		.s, .c, and .f are supported.  Note, .s files are preferred
548		to .c files of the same name.  (This is not the default for
549		versions of make.)
550
551The include file <bsd.lib.mk> includes the file named "../Makefile.inc"
552if it exists, as well as the include file <bsd.man.mk>.
553
554It has rules for building profiled objects; profiled libraries are
555built by default.
556
557Libraries are ranlib'd before installation.
558
559=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
560
561The include file <bsd.test.mk> handles building one or more test programs
562intended to be used in the FreeBSD Test Suite under /usr/tests/.
563
564It has seven targets:
565
566	all:
567		build the test programs.
568	check:
569		runs the test programs from CHECKDIR with kyua test.
570
571		The beforecheck and aftercheck targets will be invoked, if
572		defined, to execute commands before and after the realcheck
573		target has been executed, respectively.
574
575		The devel/kyua package must be installed before invoking this
576		target.
577
578		See CHECKDIR for more details.
579	clean:
580		remove the test programs and any object files.
581	cleandir:
582		remove all of the files removed by the target clean, as
583		well as .depend and tags.
584	depend:
585		make the dependencies for the source files, and store
586		them in the file .depend.
587	install:
588                install the test programs and their data files; if the
589                Makefile does not itself define the target install, the
590                targets beforeinstall and afterinstall may also be used
591                to cause actions immediately before and after the
592                install target is executed.
593	lint:
594		run lint on the source files.
595	tags:
596		create a tags file for the source files.
597
598It sets/uses the following variables, among many others:
599
600ATF_TESTS_C	The names of the ATF C test programs to build.
601
602ATF_TESTS_CXX	The names of the ATF C++ test programs to build.
603
604ATF_TESTS_SH	The names of the ATF sh test programs to build.
605
606CHECKDIR	The directory that 'make check' executes tests from.
607
608		The value of CHECKDIR defaults to .OBJDIR.
609
610KYUAFILE	If 'auto' (the default), generate a Kyuafile out of the
611		test programs defined in the Makefile.  If 'yes', then a
612		manually-crafted Kyuafile must be supplied with the
613		sources.  If 'no', no Kyuafile is installed (useful for
614		subdirectories providing helper programs or data files
615		only).
616
617LOCALBASE	The --prefix for the kyua package.
618
619		The value of LOCALBASE defaults to /usr/local .
620
621NOT_FOR_TEST_SUITE
622		If defined, none of the built test programs get
623		installed under /usr/tests/ and no Kyuafile is
624		automatically generated.  Should not be used within the
625		FreeBSD source tree but is provided for the benefit of
626		third-parties.
627
628PLAIN_TESTS_C	The names of the plain (legacy) programs to build.
629
630PLAIN_TESTS_CXX	The names of the plain (legacy) test programs to build.
631
632PLAIN_TESTS_SH	The names of the plain (legacy) test programs to build.
633
634TAP_PERL_INTERPRETER
635		Path to the Perl interpreter to be used for
636		TAP-compliant test programs that are written in Perl.
637		Refer to TAP_TESTS_PERL for details.
638
639TAP_TESTS_C	The names of the TAP-compliant C test programs to build.
640
641TAP_TESTS_CXX	The names of the TAP-compliant C++ test programs to
642		build.
643
644TAP_TESTS_PERL	The names of the TAP-compliant Perl test programs to
645		build.  The corresponding source files should end with
646		the .pl extension; the test program is marked as
647		requiring Perl; and TAP_PERL_INTERPRETER is used in the
648		built scripts as the interpreter of choice.
649
650TAP_TESTS_SH	The names of the TAP-compliant sh test programs to
651		build.
652
653TESTSBASE	Installation prefix for tests. Defaults to /usr/tests
654
655TESTSDIR	Path to the installed tests.  Must be a subdirectory of
656		TESTSBASE and the subpath should match the relative
657		location of the tests within the src tree.
658
659		The value of TESTSDIR defaults to
660		${TESTSBASE}/${RELDIR:H} , e.g. /usr/tests/bin/ls when
661		included from bin/ls/tests .
662
663TESTS_SUBDIRS	List of subdirectories containing tests into which to
664		recurse.  Differs from SUBDIR in that these directories
665		get registered into the automatically-generated
666		Kyuafile (if any).
667
668The actual building of the test programs is performed by <bsd.prog.mk>.
669Please see the documentation above for this other file for additional
670details on the behavior of <bsd.test.mk>.
671