Hi Andrii, Downloaded tarball for kernel release 5.5.4, and I cannot compile tools/testing/selftests/bpf/ with latest LLVM release version 9. Looking closer at the build error messages, I can see that this is caused by using LLVM features that (I assume) will be avail in release 10. I find it very strange that we can release a kernel that have build dependencies on a unreleased version of LLVM. I'm willing to help out, such that we can do either version or feature detection, to either skip compiling specific test programs or at least give users a proper warning of they are using a too "old" LLVM version. I love the new LLVM BTF features, but we cannot break users/CI-systems that wants to run the BPF-selftests. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer http://releases.llvm.org/download.html Compile error message: unknown builtin '__builtin_preserve_field_info' Full: make -C /home/jbrouer/build/linux-5.5.4/tools/lib/bpf OUTPUT=/home/jbrouer/build/linux-5.5.4/tools/testing/selftests/bpf/ make[1]: Entering directory '/home/jbrouer/build/linux-5.5.4/tools/lib/bpf' make[1]: Leaving directory '/home/jbrouer/build/linux-5.5.4/tools/lib/bpf' (clang -I. -I/home/jbrouer/build/linux-5.5.4/tools/testing/selftests/bpf -g -D__TARGET_ARCH_x86 -mlittle-endian -I. -I./include/uapi -I/home/jbrouer/build/linux-5.5.4/tools/include/uapi -I/home/jbrouer/build/linux-5.5.4/tools/lib/bpf -I/home/jbrouer/build/linux-5.5.4/tools/testing/selftests/usr/include -idirafter /usr/local/include -idirafter /usr/lib64/clang/9.0.0/include -idirafter /usr/include -Wno-compare-distinct-pointer-types -O2 -target bpf -emit-llvm -c progs/test_core_reloc_bitfields_probed.c -o - || echo "BPF obj compilation failed") | llc -mattr=dwarfris -march=bpf -mcpu=probe -mattr=+alu32 -filetype=obj -o /home/jbrouer/build/linux-5.5.4/tools/testing/selftests/bpf/test_core_reloc_bitfields_probed.o progs/test_core_reloc_bitfields_probed.c:47:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->ub1 = BPF_CORE_READ_BITFIELD_PROBED(in, ub1); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:48:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->ub2 = BPF_CORE_READ_BITFIELD_PROBED(in, ub2); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:49:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->ub7 = BPF_CORE_READ_BITFIELD_PROBED(in, ub7); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:50:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->sb4 = BPF_CORE_READ_BITFIELD_PROBED(in, sb4); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:51:14: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->sb20 = BPF_CORE_READ_BITFIELD_PROBED(in, sb20); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:52:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->u32 = BPF_CORE_READ_BITFIELD_PROBED(in, u32); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ progs/test_core_reloc_bitfields_probed.c:53:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration] out->s32 = BPF_CORE_READ_BITFIELD_PROBED(in, s32); ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:52:2: note: expanded from macro 'BPF_CORE_READ_BITFIELD_PROBED' __CORE_BITFIELD_PROBE_READ(&val, s, field); \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:28:10: note: expanded from macro '__CORE_BITFIELD_PROBE_READ' __CORE_RELO(src, fld, BYTE_SIZE), \ ^ /home/jbrouer/build/linux-5.5.4/tools/lib/bpf/bpf_core_read.h:23:2: note: expanded from macro '__CORE_RELO' __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) ^ 7 errors generated. llc: error: llc: <stdin>:1:1: error: expected top-level entity BPF obj compilation failed ^ make: *** [Makefile:281: /home/jbrouer/build/linux-5.5.4/tools/testing/selftests/bpf/test_core_reloc_bitfields_probed.o] Error 1
