Re: [RFC 1/2] perf: support build BPF skeletons with perf

[Jiri Olsa]

On Wed, Nov 18, 2020 at 08:50:45PM -0800, Song Liu wrote:

SNIP

> +
> +$(TMP_OUTPUT):
> +	$(call msg,MKDIR,$@)
> +	$(Q)mkdir -p $(TMP_OUTPUT)
> +
> +$(TMP_OUTPUT)/vmlinux.h: $(VMLINUX_BTF_PATH) | $(TMP_OUTPUT) $(BPFTOOL)
> +	$(call msg,GEN,$@)
> +	$(Q)if [ ! -e "$(VMLINUX_BTF_PATH)" ] ; then \
> +		echo "Couldn't find kernel BTF; set VMLINUX_BTF to"	       \
> +			"specify its location." >&2;			       \
> +		exit 1;\
> +	fi
> +	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
> +
> +$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(TMP_OUTPUT)
> +	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)			       \
> +		    OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
> +
> +$(DEFAULT_BPFTOOL): | $(TMP_OUTPUT)
> +	$(Q)$(MAKE) $(submake_extras) -C ../../../bpf/bpftool		      \
> +		    prefix= OUTPUT=$(TMP_OUTPUT)/ DESTDIR=$(TMP_OUTPUT) install

could we build just the bootstrap version of bpftool?
should be enough for skeleton and vmlinux.h dump, no?

thanks,
jirka