On 13/07/2022 19:55, Andrii Nakryiko wrote: > On Mon, Jul 11, 2022 at 7:37 PM Pu Lehui <pulehui@xxxxxxxxxx> wrote: >> >> kernel/bpf/preload/iterators use bpftool for vmlinux.h, skeleton, and >> static linking only. So we can use lightweight bootstrap version of >> bpftool to handle these, and it will be faster. >> >> Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx> >> Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> >> --- >> kernel/bpf/preload/iterators/Makefile | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/bpf/preload/iterators/Makefile b/kernel/bpf/preload/iterators/Makefile >> index bfe24f8c5a20..cf5f39f95fed 100644 >> --- a/kernel/bpf/preload/iterators/Makefile >> +++ b/kernel/bpf/preload/iterators/Makefile >> @@ -9,7 +9,7 @@ LLVM_STRIP ?= llvm-strip >> TOOLS_PATH := $(abspath ../../../../tools) >> BPFTOOL_SRC := $(TOOLS_PATH)/bpf/bpftool >> BPFTOOL_OUTPUT := $(abs_out)/bpftool >> -DEFAULT_BPFTOOL := $(OUTPUT)/sbin/bpftool >> +DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool >> BPFTOOL ?= $(DEFAULT_BPFTOOL) >> >> LIBBPF_SRC := $(TOOLS_PATH)/lib/bpf >> @@ -61,9 +61,14 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU >> OUTPUT=$(abspath $(dir $@))/ prefix= \ >> DESTDIR=$(LIBBPF_DESTDIR) $(abspath $@) install_headers >> >> +ifeq ($(CROSS_COMPILE),) >> $(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT) >> $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC) \ >> OUTPUT=$(BPFTOOL_OUTPUT)/ \ >> - LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/ \ >> - LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/ \ >> - prefix= DESTDIR=$(abs_out)/ install-bin >> + LIBBPF_BOOTSTRAP_OUTPUT=$(LIBBPF_OUTPUT)/ \ >> + LIBBPF_BOOTSTRAP_DESTDIR=$(LIBBPF_DESTDIR)/ bootstrap >> +else >> +$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT) >> + $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC) \ >> + OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap >> +endif > > another idea (related to my two previous comments for this patch set), > maybe we can teach bpftool's Makefile to reuse LIBBPF_OUTPUT as > LIBBPF_BOOTSTRAP_OUTPUT, if there is no CROSS_COMPILE? Then we can > keep iterators/Makefile, samples/bpf/Makefile and runqslower/Makefile > simpler and ignorant of CROSS_COMPILE, but still get the benefit of > not rebuilding libbpf unnecessarily in non-cross-compile mode? Could be a good idea. Seeing how the HID BPF patches add BTF/skeletons generation at new locations, I'm also starting to wonder if it would be worth having a Makefile.bpftool.include of some sort to harmonise the way we compile the bootstrap bpftool as a dependency, and make it easier to maintain. I haven't looked at how feasible that would be, yet.
