On Mon, Apr 12, 2021 at 4:29 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> To build kernel with clang, people typically use
> make -j60 LLVM=1 LLVM_IAS=1
Just as a side note:
When building with a high parallel-make-job like above "-j60" I saw
that "test_core_extern.skel.h" was not generated which is a pre-req
header file for building stuff like test_cpp.cpp.
I have in my build-script:
MAXCPUS="$(($(getconf _NPROCESSORS_ONLN)))"
MAKE_JOBS="${MAXCPUS}"
Thanks.
- Sedat -
> 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, using the above command, 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.
>
> Changelog:
> v1 -> v2:
> . add -Wno-unused-command-line-argument and -Wno-format-security
> for clang only as (1). gcc does not exhibit those
> warnings, and (2). -Wno-unused-command-line-argument is
> only supported by clang. (Sedat)
>
> 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 | 7 ++++++-
> tools/testing/selftests/lib.mk | 4 ++++
> 4 files changed, 21 insertions(+), 4 deletions(-)
>
> --
> 2.30.2
>
