Libraries should be listed last on the compiler's command line, so that the linker can look for and find still unresolved symbols. The librt library, required for the shm_* functions, was announced using CFLAGS, which puts the library *before* the source files, and fails compilation on my system: ====================== gcc -isystem /src/linux-selftests/usr/include -Wall -lrt test_cachestat.c -o /src/linux-selftests/kselftest/cachestat/test_cachestat /usr/bin/ld: /tmp/cceQWO3u.o: in function `test_cachestat_shmem': test_cachestat.c:(.text+0x890): undefined reference to `shm_open' /usr/bin/ld: test_cachestat.c:(.text+0x99c): undefined reference to `shm_unlink' collect2: error: ld returned 1 exit status make[4]: *** [../lib.mk:181: /src/linux-selftests/kselftest/cachestat/test_cachestat] Error 1 ====================== Announce the library using the LDLIBS variable, which ensures the proper ordering on the command line. Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> --- tools/testing/selftests/cachestat/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/cachestat/Makefile b/tools/testing/selftests/cachestat/Makefile index fca73aaa7d141..778b54ebb0364 100644 --- a/tools/testing/selftests/cachestat/Makefile +++ b/tools/testing/selftests/cachestat/Makefile @@ -3,6 +3,6 @@ TEST_GEN_PROGS := test_cachestat CFLAGS += $(KHDR_INCLUDES) CFLAGS += -Wall -CFLAGS += -lrt +LDLIBS += -lrt include ../lib.mk -- 2.25.1
