On 4/4/21 11:55 PM, Sedat Dilek wrote:
On Mon, Apr 5, 2021 at 4:24 AM Yonghong Song <yhs@xxxxxx> wrote:
On 4/4/21 10:25 AM, Sedat Dilek wrote:
On Sun, Apr 4, 2021 at 6:40 PM Yonghong Song <yhs@xxxxxx> wrote:
On 4/4/21 5:46 AM, Sedat Dilek wrote:
[...]
Next build-error:
g++ -g -rdynamic -Wall -O2 -DHAVE_GENHDR
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/b
pf/tools/include -I/home/dileks/src/linux-kernel/git/include/generated
-I/home/dileks/src/linux-kernel/git/tools/lib
-I/home/dileks/src/linux-kernel/git/tools/include
-I/home/dileks/src/linux-kernel/git/tools/include/uapi
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-Dbpf_prog_load=bpf_prog_test_load
-Dbpf_load_program=bpf_test_load_program test_cpp.cpp
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_core_extern.skel.h
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_stub.o
-lcap -lelf -lz -lrt -lpthread -o
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp
/usr/bin/ld: /home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a(libbpf-in.o):
relocation R_X86_64_32 against `.rodata.str1.1' ca
n not be used when making a PIE object; recompile with -fPIE
collect2: error: ld returned 1 exit status
make: *** [Makefile:455:
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp]
Error 1
make: Leaving directory
'/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf'
LOL, I was not aware that there is usage of *** CXX*** in tools
directory (see g++ line and /usr/bin/ld ?).
So, I changed my $MAKE_OPTS to use "CXX=clang++".
In kernel, if LLVM=1 is set, we have:
ifneq ($(LLVM),)
HOSTCC = clang
HOSTCXX = clang++
else
HOSTCC = gcc
HOSTCXX = g++
endif
ifneq ($(LLVM),)
CC = clang
LD = ld.lld
AR = llvm-ar
NM = llvm-nm
OBJCOPY = llvm-objcopy
OBJDUMP = llvm-objdump
READELF = llvm-readelf
STRIP = llvm-strip
else
CC = $(CROSS_COMPILE)gcc
LD = $(CROSS_COMPILE)ld
AR = $(CROSS_COMPILE)ar
NM = $(CROSS_COMPILE)nm
OBJCOPY = $(CROSS_COMPILE)objcopy
OBJDUMP = $(CROSS_COMPILE)objdump
READELF = $(CROSS_COMPILE)readelf
STRIP = $(CROSS_COMPILE)strip
endif
So if you have right path, you don't need to set HOSTCC and HOSTCXX
explicitly.
That is all correct with HOSTCXX but there is no CXX=... assignment
otherwise test_cpp will use g++ as demonstrated.
This is not a kernel Makefile issue.
We have:
testing/selftests/bpf/Makefile:CXX ?= $(CROSS_COMPILE)g++
So you need to explicit add CXX=clang++ when compiling
bpf selftests with LLVM=1 LLVM_IAS=1.
NOPE.
$ echo $MAKE $MAKE_OPTS
make V=1 LLVM=1 LLVM_IAS=1 CXX=clang++ PAHOLE=/opt/pahole/bin/pahole
$ LC_ALL=C $MAKE $MAKE_OPTS -C tools/testing/selftests/bpf/ 2>&1 | tee
../make-log_tools-testing-selftests-bpf_llvm-1-llvm_ias-1_cxx-clang.txt
This breaks again like reported before:
clang++ -g -rdynamic -Wall -O2 -DHAVE_GENHDR
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/include
-I/home/dileks/src/linux-kernel/git/include/generated
-I/home/dileks/src/linux-kernel/git/tools/lib
-I/home/dileks/src/linux-kernel/git/tools/include
-I/home/dileks/src/linux-kernel/git/tools/include/uapi
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-Dbpf_prog_load=bpf_prog_test_load
-Dbpf_load_program=bpf_test_load_program test_cpp.cpp
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_core_extern.skel.h
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_stub.o
-lcap -lelf -lz -lrt -lpthread -o
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp
clang-12: warning: treating 'c-header' input as 'c++-header' when in
C++ mode, this behavior is deprecated [-Wdeprecated]
clang-12: error: cannot specify -o when generating multiple output files
make: *** [Makefile:455:
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp]
Error 1
make: Leaving directory
'/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf'
Do you know some magic CXX flags to be passed?
I tested in my environment. The reason is LC_ALL=C.
Without LC_ALL=C, make succeeded and with it, test_cpp
compilation failed. Is it possible for you to drop
LC_ALL=C for bpf selftests?
The following command succeeded for me:
make -C tools/testing/selftests/bpf -j60 LLVM=1 V=1 CXX=clang++ CC=clang
The only solution is to suppress the build of test_cpp (see
TEST_GEN_PROGS_EXTENDED):
$ git diff tools/testing/selftests/bpf/Makefile
diff --git a/tools/testing/selftests/bpf/Makefile
b/tools/testing/selftests/bpf/Makefile
index 044bfdcf5b74..cf7c7c8f72cf 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -77,8 +77,8 @@ TEST_PROGS_EXTENDED := with_addr.sh \
# Compile but not part of 'make run_tests'
TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
- test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \
- xdpxceiver
+ test_lirc_mode2_user xdping runqslower bench bpf_testmod.ko xdpxceiver
+ # test_cpp # Suppress the build when CXX=clang++ is used
TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
I have attached both make-logs with and without suppressing the build
of test_cpp and the diff.
- Sedat -
[...]
