path: root/tools/build
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authorWang Nan <>2015-11-24 13:36:06 +0000
committerArnaldo Carvalho de Melo <>2015-11-25 16:36:36 -0300
commit5725dd8fa888b4dcdff58241f9d3d3ac42a048e2 (patch)
treecf03e731333d1e9a0397d9ecb427d3cebbcb516d /tools/build
parent4d3b16269059eee12dc572848191c8e4e7bd24b3 (diff)
tools build: Clean CFLAGS and LDFLAGS for fixdep
Sometimes passing variables to tools/build is dangerous. For example, on my platform there is a gcc problem (gcc 4.8.1): It passes the stackprotector-all feature check: $ gcc -fstack-protector-all -c ./test.c $ echo $? 0 But requires LDFLAGS support if separate compiling and linking: $ gcc -fstack-protector-all -c ./test.c $ gcc ./test.o ./test.o: In function `main': test.c:(.text+0xb): undefined reference to `__stack_chk_guard' test.c:(.text+0x21): undefined reference to `__stack_chk_guard' collect2: error: ld returned 1 exit status $ gcc -fstack-protector-all ./test.o $ echo $? 0 $ gcc ./test.o -lssp $ echo $? 0 $ In this environment building perf throws an error: $ make BUILD: Doing 'make -j24' parallel build config/Makefile:344: No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR config/Makefile:403: No libaudit.h found, disables 'trace' tool, please install audit-libs-devel or libaudit-dev config/Makefile:418: slang not found, disables TUI support. Please install slang-devel or libslang-dev config/Makefile:432: GTK2 not found, disables GTK2 support. Please install gtk2-devel or libgtk2.0-dev config/Makefile:564: No bfd.h/libbfd found, please install binutils-dev[el]/zlib-static/libiberty-dev to gain symbol demangling config/Makefile:606: No numa.h found, disables 'perf bench numa mem' benchmark, please install numactl-devel/libnuma-devel/libnuma-dev CC fixdep.o LD fixdep-in.o LINK fixdep fixdep-in.o: In function `parse_dep_file': /kernel/tools/build/fixdep.c:47: undefined reference to `__stack_chk_guard' /kernel/tools/build/fixdep.c:117: undefined reference to `__stack_chk_guard' fixdep-in.o: In function `main': /kernel-hydrogen/tools/build/fixdep.c:156: undefined reference to `__stack_chk_guard' /kernel/tools/build/fixdep.c:168: undefined reference to `__stack_chk_guard' collect2: error: ld returned 1 exit status make[2]: *** [fixdep] Error 1 make[1]: *** [fixdep] Error 2 make: *** [all] Error 2 This is because the CFLAGS used in building perf pollutes the CFLAGS used for fixdep, passing -fstack-protector-all to buiold fixdep which is obviously not required. Since fixdep is a small host side tool, we should keep its CFLAGS/LDFLAGS simple and clean. This patch clears the CFLAGS and LDFLAGS passed when building fixdep, so such gcc problem won't block the perf build process. Signed-off-by: Wang Nan <> Acked-by: Jiri Olsa <> Cc: Alexei Starovoitov <> Cc: Masami Hiramatsu <> Cc: Zefan Li <> Cc: Link: Signed-off-by: Arnaldo Carvalho de Melo <>
Diffstat (limited to 'tools/build')
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/build/Makefile.include b/tools/build/Makefile.include
index 4e09ad617a60..6254760290c9 100644
--- a/tools/build/Makefile.include
+++ b/tools/build/Makefile.include
@@ -4,7 +4,7 @@ ifdef CROSS_COMPILE
- $(Q)$(MAKE) -C $(srctree)/tools/build fixdep
+ $(Q)$(MAKE) -C $(srctree)/tools/build CFLAGS= LDFLAGS= fixdep
.PHONY: fixdep