Re: [PATCH v2 bpf-next 4/4] selftests/bpf: build everything in debug mode
From: Andrii Nakryiko <hidden>
Date: 2021-03-16 05:24:22
Also in:
bpf
On Sat, Mar 13, 2021 at 1:09 PM Andrii Nakryiko [off-list ref] wrote:
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Build selftests, bpftool, and libbpf in debug mode with DWARF data to facilitate easier debugging. In terms of impact on building and running selftests. Build is actually faster now: BEFORE: make -j60 380.21s user 37.87s system 1466% cpu 28.503 total AFTER: make -j60 345.47s user 37.37s system 1599% cpu 23.939 total test_progs runtime seems to be the same: BEFORE: real 1m5.139s user 0m1.600s sys 0m43.977s AFTER: real 1m3.799s user 0m1.721s sys 0m42.420s Huge difference is being able to debug issues throughout test_progs, bpftool, and libbpf without constantly updating 3 Makefiles by hand (including GDB seeing the source code without any extra incantations). Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- tools/testing/selftests/bpf/Makefile | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index c3999587bc23..d0db2b673c6f 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile@@ -21,7 +21,7 @@ endif BPF_GCC ?= $(shell command -v bpf-gcc;) SAN_CFLAGS ?= -CFLAGS += -g -rdynamic -Wall -O2 $(GENFLAGS) $(SAN_CFLAGS) \ +CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS) \ -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) \ -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT) \ -Dbpf_prog_load=bpf_prog_test_load \@@ -201,6 +201,7 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOLDIR) \ CC=$(HOSTCC) LD=$(HOSTLD) \ + EXTRA_CFLAGS='-g -Og' \
I was asked about '-Og' flag and the minimum GCC version that supports it. It seems it was added in GCC 4.8 ([0]), so given the kernel's minimum version is GCC 4.9, we shouldn't need take any extra precautions to handle older compilers. [0] https://gcc.gnu.org/gcc-4.8/changes.html
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OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \ prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install@@ -218,6 +219,7 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ ../../../include/uapi/linux/bpf.h \ | $(INCLUDE_DIR) $(BUILD_DIR)/libbpf $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \ + EXTRA_CFLAGS='-g -Og' \ DESTDIR=$(SCRATCH_DIR) prefix= all install_headers ifneq ($(BPFOBJ),$(HOST_BPFOBJ))@@ -225,7 +227,8 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ ../../../include/uapi/linux/bpf.h \ | $(INCLUDE_DIR) $(HOST_BUILD_DIR)/libbpf $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) \ - OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \ + EXTRA_CFLAGS='-g -Og' \ + OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \ DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers endif --2.24.1