3 mainmenu "Buildroot $BR2_VERSION Configuration"
5 config BR2_HAVE_DOT_CONFIG
11 option env="BR2_VERSION_FULL"
19 option env="BUILD_DIR"
21 # Hidden config symbols for packages to check system gcc version
22 config BR2_HOST_GCC_VERSION
24 option env="HOST_GCC_VERSION"
26 config BR2_HOST_GCC_AT_LEAST_4_5
28 default y if BR2_HOST_GCC_VERSION = "4 5"
30 config BR2_HOST_GCC_AT_LEAST_4_6
32 default y if BR2_HOST_GCC_VERSION = "4 6"
33 select BR2_HOST_GCC_AT_LEAST_4_5
35 config BR2_HOST_GCC_AT_LEAST_4_7
37 default y if BR2_HOST_GCC_VERSION = "4 7"
38 select BR2_HOST_GCC_AT_LEAST_4_6
40 config BR2_HOST_GCC_AT_LEAST_4_8
42 default y if BR2_HOST_GCC_VERSION = "4 8"
43 select BR2_HOST_GCC_AT_LEAST_4_7
45 config BR2_HOST_GCC_AT_LEAST_4_9
47 default y if BR2_HOST_GCC_VERSION = "4 9"
48 select BR2_HOST_GCC_AT_LEAST_4_8
50 config BR2_HOST_GCC_AT_LEAST_5
52 default y if BR2_HOST_GCC_VERSION = "5"
53 select BR2_HOST_GCC_AT_LEAST_4_9
55 config BR2_HOST_GCC_AT_LEAST_6
57 default y if BR2_HOST_GCC_VERSION = "6"
58 select BR2_HOST_GCC_AT_LEAST_5
60 config BR2_HOST_GCC_AT_LEAST_7
62 default y if BR2_HOST_GCC_VERSION = "7"
63 select BR2_HOST_GCC_AT_LEAST_6
65 # Hidden boolean selected by packages in need of Java in order to build
67 config BR2_NEEDS_HOST_JAVA
70 # Hidden boolean selected by packages in need of javac in order to build
71 # (example: classpath)
72 config BR2_NEEDS_HOST_JAVAC
75 # Hidden boolean selected by packages in need of jar in order to build
76 # (example: classpath)
77 config BR2_NEEDS_HOST_JAR
80 # Hidden boolean selected by pre-built packages for x86, when they
81 # need to run on x86-64 machines (example: pre-built external
82 # toolchains, binary tools like SAM-BA, etc.).
83 config BR2_HOSTARCH_NEEDS_IA32_LIBS
86 # Hidden boolean selected by packages that need to build 32 bits
87 # binaries with the host compiler, even on 64 bits build machines (e.g
89 config BR2_HOSTARCH_NEEDS_IA32_COMPILER
92 # Hidden boolean selected by packages that need the host to have an
94 config BR2_NEEDS_HOST_UTF8_LOCALE
97 source "arch/Config.in"
104 string "Wget command"
105 default "wget --passive-ftp -nd -t 3"
108 string "Subversion (svn) command"
109 default "svn --non-interactive"
112 string "Bazaar (bzr) command"
123 config BR2_LOCALFILES
124 string "Local files retrieval command"
128 string "Secure copy (scp) command"
132 string "Secure shell (ssh) command"
136 string "Mercurial (hg) command"
140 string "zcat command"
143 Command to be used to extract a gzip'ed file to stdout. zcat
144 is identical to gunzip -c except that the former may not be
145 available on your system.
146 Default is "gzip -d -c"
147 Other possible values include "gunzip -c" or "zcat".
150 string "bzcat command"
153 Command to be used to extract a bzip2'ed file to stdout.
154 bzcat is identical to bunzip2 -c except that the former may
155 not be available on your system.
157 Other possible values include "bunzip2 -c" or "bzip2 -d -c".
160 string "xzcat command"
163 Command to be used to extract a xz'ed file to stdout.
167 string "lzcat command"
170 Command to be used to extract a lzip'ed file to stdout.
171 Default is "lzip -d -c"
173 config BR2_TAR_OPTIONS
177 Options to pass to tar when extracting the sources.
178 E.g. " -v --exclude='*.svn*'" to exclude all .svn internal
179 files and to be verbose.
183 config BR2_DEFCONFIG_FROM_ENV
185 option env="BR2_DEFCONFIG"
188 string "Location to save buildroot config"
189 default BR2_DEFCONFIG_FROM_ENV if BR2_DEFCONFIG_FROM_ENV != ""
190 default "$(CONFIG_DIR)/defconfig"
192 When running 'make savedefconfig', the defconfig file will be
193 saved in this location.
196 string "Download dir"
197 default "$(TOPDIR)/dl"
199 Directory to store all the source files that we need to fetch.
200 If the Linux shell environment has defined the BR2_DL_DIR
201 environment variable, then this overrides this configuration
203 The directory is organized with a subdirectory for each package.
204 Each package has its own $(LIBFOO_DL_DIR) variable that can be used
205 to find the correct path.
207 The default is $(TOPDIR)/dl
211 default "$(BASE_DIR)/host"
213 Directory to store all the binary files that are built for the
214 host. This includes the cross compilation toolchain when
215 building the internal buildroot toolchain.
217 The default is $(BASE_DIR)/host
219 menu "Mirrors and Download locations"
221 config BR2_PRIMARY_SITE
222 string "Primary download site"
225 Primary site to download from. If this option is set then
226 buildroot will try to download package source first from this
227 site and try the default if the file is not found.
229 - URIs recognized by $(WGET)
230 - local URIs of the form file://absolutepath
231 - scp URIs of the form scp://[user@]host:path.
233 config BR2_PRIMARY_SITE_ONLY
234 bool "Only allow downloads from primary download site"
235 depends on BR2_PRIMARY_SITE != ""
237 If this option is enabled, downloads will only be attempted
238 from the primary download site. Other locations, like the
239 package's official download location or the backup download
240 site, will not be considered. Therefore, if the package is not
241 present on the primary site, the download fails.
243 This is useful for project developers who want to ensure that
244 the project can be built even if the upstream tarball
247 if !BR2_PRIMARY_SITE_ONLY
249 config BR2_BACKUP_SITE
250 string "Backup download site"
251 default "http://sources.buildroot.net"
253 Backup site to download from. If this option is set then
254 buildroot will fall back to download package sources from here
255 if the normal location fails.
257 config BR2_KERNEL_MIRROR
258 string "Kernel.org mirror"
259 default "https://cdn.kernel.org/pub"
261 kernel.org is mirrored on a number of servers around the
262 world. The following allows you to select your preferred
263 mirror. By default, a CDN is used, which automatically
264 redirects to a mirror geographically close to you.
266 Have a look on the kernel.org site for a list of mirrors, then
267 enter the URL to the base directory. Examples:
269 http://www.XX.kernel.org/pub (XX = country code)
270 http://mirror.aarnet.edu.au/pub/ftp.kernel.org
272 config BR2_GNU_MIRROR
273 string "GNU Software mirror"
274 default "http://ftpmirror.gnu.org"
276 GNU has multiple software mirrors scattered around the
277 world. The following allows you to select your preferred
278 mirror. By default, a generic address is used, which
279 automatically selects an up-to-date and local mirror.
281 Have a look on the gnu.org site for a list of mirrors, then
282 enter the URL to the base directory. Examples:
284 http://ftp.gnu.org/pub/gnu
285 http://mirror.aarnet.edu.au/pub/gnu
287 config BR2_LUAROCKS_MIRROR
288 string "LuaRocks mirror"
289 default "http://rocks.moonscript.org"
293 See http://luarocks.org
295 config BR2_CPAN_MIRROR
296 string "CPAN mirror (Perl packages)"
297 default "http://cpan.metacpan.org"
299 CPAN (Comprehensive Perl Archive Network) is a repository of
300 Perl packages. It has multiple software mirrors scattered
301 around the world. This option allows you to select a mirror.
303 The list of mirrors is available at:
304 http://search.cpan.org/mirror
311 int "Number of jobs to run simultaneously (0 for auto)"
314 Number of jobs to run simultaneously. If 0, determine
315 automatically according to number of CPUs on the host system.
318 bool "Enable compiler cache"
320 This option will enable the use of ccache, a compiler cache.
321 It will cache the result of previous builds to speed up future
322 builds. By default, the cache is stored in
323 $HOME/.buildroot-ccache.
325 Note that Buildroot does not try to invalidate the cache
326 contents when the compiler changes in an incompatible way.
327 Therefore, if you make a change to the compiler version and/or
328 configuration, you are responsible for purging the ccache
329 cache by removing the $HOME/.buildroot-ccache directory.
333 config BR2_CCACHE_DIR
334 string "Compiler cache location"
335 default "$(HOME)/.buildroot-ccache"
337 Where ccache should store cached files.
338 If the Linux shell environment has defined the BR2_CCACHE_DIR
339 environment variable, then this overrides this configuration
342 config BR2_CCACHE_INITIAL_SETUP
343 string "Compiler cache initial setup"
345 Initial ccache settings to apply, such as --max-files or
348 For example, if your project is known to require more space
349 than the default max cache size, then you might want to
350 increase the cache size to a suitable amount using the -M
353 The string you specify here is passed verbatim to ccache.
354 Refer to ccache documentation for more details.
356 These initial settings are applied after ccache has been
359 config BR2_CCACHE_USE_BASEDIR
360 bool "Use relative paths"
363 Allow ccache to convert absolute paths within the output
364 directory into relative paths.
366 During the build, many -I include directives are given with an
367 absolute path. These absolute paths end up in the hashes that
368 are computed by ccache. Therefore, when you build from a
369 different directory, the hash will be different and the cached
370 object will not be used.
372 To improve cache performance, set this option to y. This
373 allows ccache to rewrite absolute paths within the output
374 directory into relative paths. Note that only paths within the
375 output directory will be rewritten; therefore, if you change
376 BR2_HOST_DIR to point outside the output directory and
377 subsequently move it to a different location, this will lead
380 This option has as a result that the debug information in the
381 object files also has only relative paths. Therefore, make
382 sure you cd to the build directory before starting gdb. See
383 the section "COMPILING IN DIFFERENT DIRECTORIES" in the ccache
384 manual for more information.
388 config BR2_ENABLE_DEBUG
389 bool "build packages with debugging symbols"
391 Build packages with debugging symbols enabled. All libraries
392 and binaries in the 'staging' directory will have debugging
393 symbols, which allows remote debugging even if libraries and
394 binaries are stripped on the target. Whether libraries and
395 binaries are stripped on the target is controlled by the
396 BR2_STRIP_* options below.
400 prompt "gcc debug level"
403 Set the debug level for gcc
408 Debug level 1 produces minimal information, enough for making
409 backtraces in parts of the program that you don't plan to
410 debug. This includes descriptions of functions and external
411 variables, but no information about local variables and no
417 The default gcc debug level is 2
422 Level 3 includes extra information, such as all the macro
423 definitions present in the program. Some debuggers support
424 macro expansion when you use -g3.
428 config BR2_STRIP_strip
429 bool "strip target binaries"
431 depends on !BR2_PACKAGE_HOST_ELF2FLT
433 Binaries and libraries in the target filesystem will be
434 stripped using the normal 'strip' command. This allows to save
435 space, mainly by removing debugging symbols. Debugging symbols
436 on the target are needed for native debugging, but not when
437 remote debugging is used.
439 config BR2_STRIP_EXCLUDE_FILES
440 string "executables that should not be stripped"
442 depends on BR2_STRIP_strip
444 You may specify a space-separated list of binaries and
445 libraries here that should not be stripped on the target.
447 config BR2_STRIP_EXCLUDE_DIRS
448 string "directories that should be skipped when stripping"
450 depends on BR2_STRIP_strip
452 You may specify a space-separated list of directories that
453 should be skipped when stripping. Binaries and libraries in
454 these directories will not be touched. The directories should
455 be specified relative to the target directory, without leading
459 prompt "gcc optimization level"
460 default BR2_OPTIMIZE_S
462 Set the optimization level for gcc
464 config BR2_OPTIMIZE_0
465 bool "optimization level 0"
469 config BR2_OPTIMIZE_1
470 bool "optimization level 1"
472 Optimize. Optimizing compilation takes somewhat more time, and
473 a lot more memory for a large function. With -O, the compiler
474 tries to reduce code size and execution time, without
475 performing any optimizations that take a great deal of
476 compilation time. -O turns on the following optimization
477 flags: -fdefer-pop -fdelayed-branch -fguess-branch-probability
478 -fcprop-registers -floop-optimize -fif-conversion
479 -fif-conversion2 -ftree-ccp -ftree-dce -ftree-dominator-opts
480 -ftree-dse -ftree-ter -ftree-lrs -ftree-sra -ftree-copyrename
481 -ftree-fre -ftree-ch -funit-at-a-time -fmerge-constants. -O
482 also turns on -fomit-frame-pointer on machines where doing so
483 does not interfere with debugging.
485 config BR2_OPTIMIZE_2
486 bool "optimization level 2"
488 Optimize even more. GCC performs nearly all supported
489 optimizations that do not involve a space-speed tradeoff. The
490 compiler does not perform loop unrolling or function inlining
491 when you specify -O2. As compared to -O, this option increases
492 both compilation time and the performance of the generated
493 code. -O2 turns on all optimization flags specified by -O. It
494 also turns on the following optimization flags:
495 -fthread-jumps -fcrossjumping -foptimize-sibling-calls
496 -fcse-follow-jumps -fcse-skip-blocks -fgcse -fgcse-lm
497 -fexpensive-optimizations -fstrength-reduce
498 -frerun-cse-after-loop -frerun-loop-opt -fcaller-saves
499 -fpeephole2 -fschedule-insns -fschedule-insns2
500 -fsched-interblock -fsched-spec -fregmove -fstrict-aliasing
501 -fdelete-null-pointer-checks -freorder-blocks
502 -freorder-functions -falign-functions -falign-jumps
503 -falign-loops -falign-labels -ftree-vrp -ftree-pre. Please
504 note the warning under -fgcse about invoking -O2 on programs
505 that use computed gotos.
507 config BR2_OPTIMIZE_3
508 bool "optimization level 3"
510 Optimize yet more. -O3 turns on all optimizations specified by
511 -O2 and also turns on the -finline-functions, -funswitch-loops
512 and -fgcse-after-reload options.
514 config BR2_OPTIMIZE_G
515 bool "optimize for debugging"
516 depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
518 Optimize for debugging. This enables optimizations that do not
519 interfere with debugging. It should be the optimization level
520 of choice for the standard edit-compile-debug cycle, offering
521 a reasonable level of optimization while maintaining fast
522 compilation and a good debugging experience.
524 config BR2_OPTIMIZE_S
525 bool "optimize for size"
527 Optimize for size. -Os enables all -O2 optimizations that do
528 not typically increase code size. It also performs further
529 optimizations designed to reduce code size. -Os disables the
530 following optimization flags: -falign-functions -falign-jumps
531 -falign-loops -falign-labels -freorder-blocks
532 -freorder-blocks-and-partition -fprefetch-loop-arrays
533 -ftree-vect-loop-version
536 config BR2_OPTIMIZE_FAST
537 bool "optimize for fast"
538 depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_6
540 Optimize for fast. Disregard strict standards
541 compliance. -Ofast enables all -O3 optimizations. It also
542 enables optimizations that are not valid for all
543 standard-compliant programs. It turns on -ffast-math and the
544 Fortran-specific -fstack-arrays, unless -fmax-stack-var-size
545 is specified, and -fno-protect-parens.
549 config BR2_GOOGLE_BREAKPAD_ENABLE
550 bool "Enable google-breakpad support"
551 depends on BR2_INSTALL_LIBSTDCPP
552 depends on BR2_HOST_GCC_AT_LEAST_4_8 # C++11
553 depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 # C++11
554 depends on BR2_USE_WCHAR
555 depends on BR2_TOOLCHAIN_HAS_THREADS
556 depends on (BR2_TOOLCHAIN_USES_GLIBC || BR2_TOOLCHAIN_USES_UCLIBC)
557 depends on BR2_PACKAGE_GOOGLE_BREAKPAD_ARCH_SUPPORTS
558 depends on BR2_PACKAGE_HOST_GOOGLE_BREAKPAD_ARCH_SUPPORTS
559 select BR2_PACKAGE_GOOGLE_BREAKPAD
561 This option will enable the use of google breakpad, a library
562 and tool suite that allows you to distribute an application to
563 users with compiler-provided debugging information removed,
564 record crashes in compact "minidump" files, send them back to
565 your server and produce C and C++ stack traces from these
566 minidumps. Breakpad can also write minidumps on request for
567 programs that have not crashed.
569 if BR2_GOOGLE_BREAKPAD_ENABLE
571 config BR2_GOOGLE_BREAKPAD_INCLUDE_FILES
572 string "List of executables and libraries to extract symbols from"
575 You may specify a space-separated list of binaries and
576 libraries with full paths relative to $(TARGET_DIR) of which
577 debug symbols will be dumped for further use with google
580 A directory structure that can be used by minidump-stackwalk
583 $(STAGING_DIR)/usr/share/google-breakpad-symbols
589 default BR2_SHARED_LIBS if BR2_BINFMT_SUPPORTS_SHARED
590 default BR2_STATIC_LIBS if !BR2_BINFMT_SUPPORTS_SHARED
592 Select the type of libraries you want to use on the target.
594 The default is to build dynamic libraries and use those on the
595 target filesystem, except when the architecture and/or the
596 selected binary format does not support shared libraries.
598 config BR2_STATIC_LIBS
601 Build and use only static libraries. No shared libraries will
602 be installed on the target. This potentially increases your
603 code size and should only be used if you know what you are
604 doing. Note that some packages may not be available when this
605 option is enabled, due to their need for dynamic library
608 config BR2_SHARED_LIBS
610 depends on BR2_BINFMT_SUPPORTS_SHARED
612 Build and use only shared libraries. This is the recommended
613 solution as it saves space and build time.
615 config BR2_SHARED_STATIC_LIBS
616 bool "both static and shared"
617 depends on BR2_BINFMT_SUPPORTS_SHARED
619 Build both shared and static libraries, but link executables
620 dynamically. While building both shared and static libraries
621 take more time and more disk space, having static libraries
622 may be useful to link some of the applications statically.
626 config BR2_PACKAGE_OVERRIDE_FILE
627 string "location of a package override file"
628 default "$(CONFIG_DIR)/local.mk"
630 A package override file is a short makefile that contains
631 variable definitions of the form <pkg>_OVERRIDE_SRCDIR, which
632 allows to tell Buildroot to use an existing directory as the
633 source directory for a particular package. See the Buildroot
634 documentation for more details on this feature.
636 config BR2_GLOBAL_PATCH_DIR
637 string "global patch directories"
639 You may specify a space separated list of one or more
640 directories containing global package patches. For a specific
641 version <packageversion> of a specific package <packagename>,
642 patches are applied as follows:
644 First, the default Buildroot patch set for the package is
645 applied from the package's directory in Buildroot.
647 Then for every directory - <global-patch-dir> - that exists in
648 BR2_GLOBAL_PATCH_DIR, if the directory
649 <global-patch-dir>/<packagename>/<packageversion>/ exists,
650 then all *.patch files in this directory will be applied.
652 Otherwise, if the directory <global-patch-dir>/<packagename>
653 exists, then all *.patch files in the directory will be
658 config BR2_COMPILER_PARANOID_UNSAFE_PATH
659 bool "paranoid check of library/header paths"
662 By default, when this option is disabled, when the Buildroot
663 cross-compiler will encounter an unsafe library or header path
664 (such as /usr/include, or /usr/lib), the compiler will display
667 By enabling this option, this warning is turned into an error,
668 which will completely abort the build when such unsafe paths
671 Note that this mechanism is available for both the internal
672 toolchain (through the toolchain wrapper and binutils patches)
673 and external toolchain backends (through the toolchain
676 config BR2_REPRODUCIBLE
677 bool "Make the build reproducible (experimental)"
678 # SOURCE_DATE_EPOCH support in toolchain-wrapper requires GCC 4.4
679 depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_4
681 This option will remove all sources of non-reproducibility
682 from the build process. For a given Buildroot configuration,
683 this allows to generate exactly identical binaries from one
684 build to the other, including on different machines.
686 The current implementation is restricted to builds with the
687 same output directory. Many (absolute) paths are recorded in
688 intermediary files, and it is very likely that some of these
689 paths leak into the target rootfs. If you build with the
690 same O=... path, however, the result is identical.
692 This is labeled as an experimental feature, as not all
693 packages behave properly to ensure reproducibility.
697 comment "Security Hardening Options"
700 bool "Stack Smashing Protection"
701 default BR2_SSP_ALL if BR2_ENABLE_SSP # legacy
702 depends on BR2_TOOLCHAIN_HAS_SSP
704 Enable stack smashing protection support using GCC's
705 -fstack-protector option family.
708 http://www.linuxfromscratch.org/hints/downloads/files/ssp.txt
711 Note that this requires the toolchain to have SSP support.
712 This is always the case for glibc and eglibc toolchain, but is
713 optional in uClibc toolchains.
718 Disable stack-smashing protection.
720 config BR2_SSP_REGULAR
721 bool "-fstack-protector"
723 Emit extra code to check for buffer overflows, such as stack
724 smashing attacks. This is done by adding a guard variable to
725 functions with vulnerable objects. This includes functions
726 that call alloca, and functions with buffers larger than 8
727 bytes. The guards are initialized when a function is entered
728 and then checked when the function exits. If a guard check
729 fails, an error message is printed and the program exits.
731 config BR2_SSP_STRONG
732 bool "-fstack-protector-strong"
733 depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
735 Like -fstack-protector but includes additional functions to be
736 protected - those that have local array definitions, or have
737 references to local frame addresses.
739 comment "Stack Smashing Protection strong needs a toolchain w/ gcc >= 4.9"
740 depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
743 bool "-fstack-protector-all"
745 Like -fstack-protector except that all functions are
746 protected. This option might have a significant performance
747 impact on the compiled binaries.
751 comment "Stack Smashing Protection needs a toolchain w/ SSP"
752 depends on !BR2_TOOLCHAIN_HAS_SSP
755 bool "RELRO Protection"
756 depends on BR2_SHARED_LIBS
758 Enable a link-time protection know as RELRO (RELocation Read
759 Only) which helps to protect from certain type of exploitation
760 techniques altering the content of some ELF sections.
762 config BR2_RELRO_NONE
765 Disables Relocation link-time protections.
767 config BR2_RELRO_PARTIAL
770 This option makes the dynamic section not writeable after
771 initialization (with almost no performance penalty).
773 config BR2_RELRO_FULL
776 This option includes the partial configuration, but also marks
777 the GOT as read-only at the cost of initialization time during
778 program loading, i.e every time an executable is started.
782 comment "RELocation Read Only (RELRO) needs shared libraries"
783 depends on !BR2_SHARED_LIBS
786 bool "Buffer-overflow Detection (FORTIFY_SOURCE)"
787 depends on BR2_TOOLCHAIN_USES_GLIBC
788 depends on !BR2_OPTIMIZE_0
790 Enable the _FORTIFY_SOURCE macro which introduces additional
791 checks to detect buffer-overflows in the following standard
792 library functions: memcpy, mempcpy, memmove, memset, strcpy,
793 stpcpy, strncpy, strcat, strncat, sprintf, vsprintf, snprintf,
796 NOTE: This feature requires an optimization level of s/1/2/3/g
798 Support for this feature has been present since GCC 4.x.
800 config BR2_FORTIFY_SOURCE_NONE
803 Disables additional checks to detect buffer-overflows.
805 config BR2_FORTIFY_SOURCE_1
808 This option sets _FORTIFY_SOURCE to 1 and only introduces
809 checks that shouldn't change the behavior of conforming
810 programs. Adds checks at compile-time only.
812 config BR2_FORTIFY_SOURCE_2
815 This option sets _FORTIFY_SOURCES to 2 and some more
816 checking is added, but some conforming programs might fail.
817 Also adds checks at run-time (detected buffer overflow
818 terminates the program)
822 comment "Fortify Source needs a glibc toolchain and optimization"
823 depends on (!BR2_TOOLCHAIN_USES_GLIBC || BR2_OPTIMIZE_0)
826 source "toolchain/Config.in"
828 source "system/Config.in"
830 source "linux/Config.in"
832 source "package/Config.in"
834 source "fs/Config.in"
836 source "boot/Config.in"
838 source "package/Config.in.host"
840 source "Config.in.legacy"
842 source "$BR2_BUILD_DIR/.br2-external.in"