On Sun, Oct 3, 2021 at 12:22 PM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote: > > API headers from libbpf should not be accessed directly from the > library's source directory. Instead, they should be exported with "make > install_headers". Let's make sure that runqslower installs the > headers properly when building. > > We use a libbpf_hdrs target to mark the logical dependency on libbpf's > headers export for a number of object files, even though the headers > should have been exported at this time (since bpftool needs them, and is > required to generate the skeleton or the vmlinux.h). > > When descending from a parent Makefile, the specific output directories > for building the library and exporting the headers are configurable with > BPFOBJ_OUTPUT and BPF_DESTDIR, respectively. This is in addition to > OUTPUT, on top of which those variables are constructed by default. > > Also adjust the Makefile for the BPF selftests. We pass a number of > variables to the "make" invocation, because we want to point runqslower > to the (target) libbpf shared with other tools, instead of building its > own version. In addition, runqslower relies on (target) bpftool, and we > also want to pass the proper variables to its Makefile so that bpftool > itself reuses the same libbpf. > > Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> > --- > tools/bpf/runqslower/Makefile | 22 +++++++++++++--------- > tools/testing/selftests/bpf/Makefile | 15 +++++++++------ > 2 files changed, 22 insertions(+), 15 deletions(-) > > diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile > index 3818ec511fd2..049aef7e9a4c 100644 > --- a/tools/bpf/runqslower/Makefile > +++ b/tools/bpf/runqslower/Makefile > @@ -9,9 +9,9 @@ BPFTOOL ?= $(DEFAULT_BPFTOOL) > LIBBPF_SRC := $(abspath ../../lib/bpf) > BPFOBJ_OUTPUT := $(OUTPUT)libbpf/ > BPFOBJ := $(BPFOBJ_OUTPUT)libbpf.a > -BPF_INCLUDE := $(BPFOBJ_OUTPUT) > -INCLUDES := -I$(OUTPUT) -I$(BPF_INCLUDE) -I$(abspath ../../lib) \ > - -I$(abspath ../../include/uapi) > +BPF_DESTDIR := $(BPFOBJ_OUTPUT) > +BPF_INCLUDE := $(BPF_DESTDIR)/include > +INCLUDES := -I$(OUTPUT) -I$(BPF_INCLUDE) -I$(abspath ../../include/uapi) > CFLAGS := -g -Wall > > # Try to detect best kernel BTF source > @@ -33,7 +33,7 @@ endif > > .DELETE_ON_ERROR: > > -.PHONY: all clean runqslower > +.PHONY: all clean runqslower libbpf_hdrs > all: runqslower > > runqslower: $(OUTPUT)/runqslower > @@ -46,13 +46,15 @@ clean: > $(Q)$(RM) $(OUTPUT)runqslower > $(Q)$(RM) -r .output > > +libbpf_hdrs: $(BPFOBJ) > + > $(OUTPUT)/runqslower: $(OUTPUT)/runqslower.o $(BPFOBJ) > $(QUIET_LINK)$(CC) $(CFLAGS) $^ -lelf -lz -o $@ > > $(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h \ > - $(OUTPUT)/runqslower.bpf.o > + $(OUTPUT)/runqslower.bpf.o libbpf_hdrs this phony dependency will cause runqslower.o to be always rebuilt, try running make multiple times with no changes inside tools/bpf/runqslower. Can this be done just as an order-only dependency? > > -$(OUTPUT)/runqslower.bpf.o: $(OUTPUT)/vmlinux.h runqslower.h > +$(OUTPUT)/runqslower.bpf.o: $(OUTPUT)/vmlinux.h runqslower.h libbpf_hdrs > > $(OUTPUT)/%.skel.h: $(OUTPUT)/%.bpf.o | $(BPFTOOL) > $(QUIET_GEN)$(BPFTOOL) gen skeleton $< > $@ [...]
