| Message ID | 20190829105645.12285-2-quentin.monnet@netronome.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | tools: bpftool: improve bpftool build experience | expand |
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index f284c207765a..cd0fc05464e7 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -24,7 +24,7 @@ endif LIBBPF = $(BPF_PATH)libbpf.a -BPFTOOL_VERSION := $(shell make --no-print-directory -sC ../../.. kernelversion) +BPFTOOL_VERSION := $(shell make -rR --no-print-directory -sC ../../.. kernelversion) $(LIBBPF): FORCE $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(OUTPUT) $(OUTPUT)libbpf.a
Bpftool calls the toplevel Makefile to get the kernel version for the sources it is built from. But when the utility is built from the top of the kernel repository, it may dump the following error message for certain architectures (including x86): $ make tools/bpf [...] make[3]: *** [checkbin] Error 1 [...] This does not prevent bpftool compilation, but may feel disconcerting. The "checkbin" arch-dependent target is not supposed to be called for target "kernelversion", which is a simple "echo" of the version number. It turns out this is caused by the make invocation in tools/bpf/bpftool, which attempts to find implicit rules to apply. Extract from debug output: Reading makefiles... Reading makefile 'Makefile'... Reading makefile 'scripts/Kbuild.include' (search path) (no ~ expansion)... Reading makefile 'scripts/subarch.include' (search path) (no ~ expansion)... Reading makefile 'arch/x86/Makefile' (search path) (no ~ expansion)... Reading makefile 'scripts/Makefile.kcov' (search path) (no ~ expansion)... Reading makefile 'scripts/Makefile.gcc-plugins' (search path) (no ~ expansion)... Reading makefile 'scripts/Makefile.kasan' (search path) (no ~ expansion)... Reading makefile 'scripts/Makefile.extrawarn' (search path) (no ~ expansion)... Reading makefile 'scripts/Makefile.ubsan' (search path) (no ~ expansion)... Updating makefiles.... Considering target file 'scripts/Makefile.ubsan'. Looking for an implicit rule for 'scripts/Makefile.ubsan'. Trying pattern rule with stem 'Makefile.ubsan'. [...] Trying pattern rule with stem 'Makefile.ubsan'. Trying implicit prerequisite 'scripts/Makefile.ubsan.o'. Looking for a rule with intermediate file 'scripts/Makefile.ubsan.o'. Avoiding implicit rule recursion. Trying pattern rule with stem 'Makefile.ubsan'. Trying rule prerequisite 'prepare'. Trying rule prerequisite 'FORCE'. Found an implicit rule for 'scripts/Makefile.ubsan'. Considering target file 'prepare'. File 'prepare' does not exist. Considering target file 'prepare0'. File 'prepare0' does not exist. Considering target file 'archprepare'. File 'archprepare' does not exist. Considering target file 'archheaders'. File 'archheaders' does not exist. Finished prerequisites of target file 'archheaders'. Must remake target 'archheaders'. Putting child 0x55976f4f6980 (archheaders) PID 31743 on the chain. To avoid that, pass the -r and -R flags to eliminate the use of make built-in rules (and while at it, built-in variables) when running command "make kernelversion" from bpftool's Makefile. Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> --- tools/bpf/bpftool/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)