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In commit26e37cef16, we started using __WORDSIZE to get the size of longs on the given architecture, in order to support all CPU architectures. Unfortunately, __WORDSIZE is not enabled in musl, so in19bd089004, we switched to using LONG_BIT instead of __WORDSIZE. However, LONG_BIT is not readily available on glibc, you need _XOPEN_SOURCE to be defined, which was done ina34e7f88f6. However, ina34e7f88f6, _XOPEN_SOURCE was just defined, with no specific value. This caused the build to break again on uClibc-ng and older glibcs, because clock_gettime() and CLOCK_MONOTONIC were no longer defined. In both uClibc-ng and glibc, CLOCK_MONOTONIC is only defined if __USE_POSIX199309 is defined. It turns out that simply defining _XOPEN_SOURCE with no value does not lead to __USE_POSIX199309 being defined in uClibc-ng and old glibcs, while it is defined in newer glibcs. The difference comes from the following snippet of code, which is present in recent enough glibc's <feature.h> but not uClibc-ng's or older glibc's <feature.h>: /* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE is defined, use POSIX.1-2008 (or another version depending on _XOPEN_SOURCE). */ So the fact that we are defining _DEFAULT_SOURCE makes it assume that we're using POSIX 2008.09, which obviously includes POSIX 1993.09. Due to the lack of this code snippet, uClibc-ng <features.h> only enables: !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE) but not: So we need an _XOPEN_SOURCE level of at least 500 for POSIX 1993.09 definitions to be available. This is confirmed by the feature_test_macros man page, which states: _XOPEN_SOURCE < 500 _POSIX_C_SOURCE is defined with the value 2. 500 <= _XOPEN_SOURCE < 600 _POSIX_C_SOURCE is defined with the value 199506L. When this is fixed, another issue arises with older glibc toolchains (such as Sourcery ARM), where fd_set is no longer defined. Inded, with POSIX-1.2001 being enabled, we need to include <sys/select.h> to access the fd_set definition and friends (see man fd_set for details). This commit was tested with two glibc toolchains (recent and old), one uClibc-ng toolchain and one musl toolchain. Fixes: http://autobuild.buildroot.net/results/e20f9474fc0217036faa6561df33fa983466ddfe/ (uClibc-ng) http://autobuild.buildroot.net/results/b5d944389fc96ef2c5e0608fe4ac34149e5f9739/ (glibc) Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Acked-by: Vincent Fazio <vfazio@gmail.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at http://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on Freenode IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches