On 5/30/23 15:29, Jiri Olsa wrote: > On Tue, May 30, 2023 at 02:33:52PM +0200, Viktor Malik wrote: >> Building BPF selftests with custom HOSTCFLAGS yields an error: >> >> # make HOSTCFLAGS="-O2" >> [...] >> HOSTCC ./tools/testing/selftests/bpf/tools/build/resolve_btfids/main.o >> main.c:73:10: fatal error: linux/rbtree.h: No such file or directory >> 73 | #include <linux/rbtree.h> >> | ^~~~~~~~~~~~~~~~ >> >> The reason is that tools/bpf/resolve_btfids/Makefile passes header >> include paths by extending HOSTCFLAGS which is overridden by setting >> HOSTCFLAGS in the make command (because of Makefile rules [1]). >> >> This patch fixes the above problem by passing the include paths via >> `HOSTCFLAGS_resolve_btfids` which is used by tools/build/Build.include >> and can be combined with overridding HOSTCFLAGS. >> >> [1] https://www.gnu.org/software/make/manual/html_node/Overriding.html >> >> Fixes: 56a2df7615fa ("tools/resolve_btfids: Compile resolve_btfids as host program") >> Signed-off-by: Viktor Malik <vmalik@xxxxxxxxxx> >> --- >> tools/bpf/resolve_btfids/Makefile | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile >> index ac548a7baa73..4b8079f294f6 100644 >> --- a/tools/bpf/resolve_btfids/Makefile >> +++ b/tools/bpf/resolve_btfids/Makefile >> @@ -67,7 +67,7 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU >> LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) >> LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) >> >> -HOSTCFLAGS += -g \ >> +HOSTCFLAGS_resolve_btfids += -g \ >> -I$(srctree)/tools/include \ >> -I$(srctree)/tools/include/uapi \ >> -I$(LIBBPF_INCLUDE) \ >> @@ -76,7 +76,7 @@ HOSTCFLAGS += -g \ >> >> LIBS = $(LIBELF_LIBS) -lz >> >> -export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR >> +export srctree OUTPUT HOSTCFLAGS_resolve_btfids Q HOSTCC HOSTLD HOSTAR > > hum, AFAICS this way the spacified HOSTCFLAGS="-O2" won't be pushed > to the libbpf and libsubcmd dependencies, right? IIUC, it will, b/c we're doing: HOST_OVERRIDES := ... EXTRA_CFLAGS="$(HOSTCFLAGS)" and then pass HOST_OVERRIDES to libbpf and libsubcmd builds, which will then pick EXTRA_CFLAGS as a part of their build. Confirmed for libsubcmd: $ make HOSTCFLAGS="-O2" V=1 | grep libsubcmd | grep O2 | wc -l 14 $ make V=1 | grep libsubcmd | grep O2 | wc -l 0 Interestingly, I couldn't do the same for libbpf. It looks like libbpf is not rebuilt for resolve_btfids b/c resolve_btfids/Makefile uses $(BPFOBJ) as the libbpf target and selftests/bpf/Makefile passes BPFOBJ=$(HOST_BPFOBJ) to the resolve_btfids build. So, an already built libbpf is reused and that one hasn't picked HOSTCFLAGS. > how about we add the EXTRA_CFLAGS variable like we do in libbpf, > libsubcmd or perf > > with the change below you'd need to run: > > $ make EXTRA_CFLAGS="-O2" > I'd like to avoid that b/c then, we would need to issue a different make command for the BPF selftests than for the rest of the kernel to pass custom flags to host-built programs. > I'll dig up the cross build scenarious we broke last time we > touched this stuff, perhaps Ian might remember as well ;-) That will be useful, thanks :-) Viktor > > jirka > > > --- > diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile > index ac548a7baa73..58cfedc9c2db 100644 > --- a/tools/bpf/resolve_btfids/Makefile > +++ b/tools/bpf/resolve_btfids/Makefile > @@ -18,8 +18,8 @@ else > endif > > # Overrides for the prepare step libraries. > -HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \ > - CROSS_COMPILE="" EXTRA_CFLAGS="$(HOSTCFLAGS)" > +HOST_OVERRIDES = AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)" \ > + CROSS_COMPILE="" > > RM ?= rm > HOSTCC ?= gcc > @@ -67,7 +67,7 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU > LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) > LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) > > -HOSTCFLAGS += -g \ > +HOSTCFLAGS += $(EXTRA_CFLAGS) -g \ > -I$(srctree)/tools/include \ > -I$(srctree)/tools/include/uapi \ > -I$(LIBBPF_INCLUDE) \ > @@ -76,7 +76,7 @@ HOSTCFLAGS += -g \ > > LIBS = $(LIBELF_LIBS) -lz > > -export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR > +export srctree OUTPUT HOSTCFLAGS Q HOSTCC HOSTLD HOSTAR EXTRA_CFLAGS > include $(srctree)/tools/build/Makefile.include > > $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT) >
