On 4/10/21 12:19 PM, Sedat Dilek wrote:
On Sat, Apr 10, 2021 at 6:49 PM Yonghong Song <yhs@xxxxxx> wrote:To build kernel with clang, people typically use make -j60 LLVM=1 LLVM_IAS=1 LLVM_IAS=1 is not required for non-LTO build but is required for LTO build. In my environment, I am always having LLVM_IAS=1 regardless of whether LTO is enabled or not. After kernel is build with clang, the following command can be used to build selftests with clang: make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1 But currently, some compilations still use gcc and there are also compilation errors and warnings. This patch set intends to fix these issues. Patch #1 and #2 fixed the issue so clang/clang++ is used instead of gcc/g++. Patch #3 fixed a compilation failure. Patch #4 and #5 fixed various compiler warnings. Yonghong Song (5): selftests: set CC to clang in lib.mk if LLVM is set tools: allow proper CC/CXX/... override with LLVM=1 in Makefile.include selftests/bpf: fix test_cpp compilation failure with clang selftests/bpf: silence clang compilation warnings bpftool: fix a clang compilation warning tools/bpf/bpftool/net.c | 2 +- tools/scripts/Makefile.include | 12 ++++++++++-- tools/testing/selftests/bpf/Makefile | 4 +++- tools/testing/selftests/lib.mk | 4 ++++ 4 files changed, 18 insertions(+), 4 deletions(-) -- 2.30.2Thanks for CCing me and taking care to clean BPF selftests with clang. I applied (adapted 4/5) the 5 patches to fit latest Linus Git. As I had a fresh compiled Clang-CFI kernel without enabling BTF debug-info KConfig this fails at some point. I am not sure what the situation is with Clang-CFI + BTF thus I will do another Clang-LTO build with BTF enabled. So, I was not able to build test_cpp. I am missing some comments that LLVM=1 misses to set CXX=clang++ if people want that explicitly as CXX. Did you try with this?
Yes, this patch set should fix this issue.
AFAICS LC_ALL=C was not the culprit. Did you try with and without LC_ALL=C - I have this in all my build-scripts. Here I have German localisation as default.
Just tried. Yes, LC_ALL=C does not impact compilation any more with this patch set.
Wil report later... (might be Monday when Linux v5.12-rc7 is released). - Sedat -
