On Thu, Jan 21, 2021 at 01:27:35PM +0800, Tiezhu Yang wrote: > The current LLVM and Clang build procedure in samples/bpf/README.rst is > out of date. See below that the links are not accessible any more. > > $ git clone http://llvm.org/git/llvm.git > Cloning into 'llvm'... > fatal: unable to access 'http://llvm.org/git/llvm.git/': Maximum (20) redirects followed > $ git clone --depth 1 http://llvm.org/git/clang.git > Cloning into 'clang'... > fatal: unable to access 'http://llvm.org/git/clang.git/': Maximum (20) redirects followed > > The LLVM community has adopted new ways to build the compiler. There are > different ways to build LLVM and Clang, the Clang Getting Started page [1] > has one way. As Yonghong said, it is better to copy the build procedure > in Documentation/bpf/bpf_devel_QA.rst to keep consistent. > > I verified the procedure and it is proved to be feasible, so we should > update README.rst to reflect the reality. At the same time, update the > related comment in Makefile. > > Additionally, as Fangrui said, the dir llvm-project/llvm/build/install is > not used, BUILD_SHARED_LIBS=OFF is the default option [2], so also change > Documentation/bpf/bpf_devel_QA.rst together. > > [1] https://clang.llvm.org/get_started.html > [2] https://www.llvm.org/docs/CMake.html > > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> > Acked-by: Yonghong Song <yhs@xxxxxx> Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Small comment below. > --- > > v2: Update the commit message suggested by Yonghong, > thank you very much. > > v3: Remove the default option BUILD_SHARED_LIBS=OFF > and just mkdir llvm-project/llvm/build suggested > by Fangrui. > > Documentation/bpf/bpf_devel_QA.rst | 3 +-- > samples/bpf/Makefile | 2 +- > samples/bpf/README.rst | 16 +++++++++------- > 3 files changed, 11 insertions(+), 10 deletions(-) > > diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst > index 5b613d2..18788bb 100644 > --- a/Documentation/bpf/bpf_devel_QA.rst > +++ b/Documentation/bpf/bpf_devel_QA.rst > @@ -506,11 +506,10 @@ that set up, proceed with building the latest LLVM and clang version > from the git repositories:: > > $ git clone https://github.com/llvm/llvm-project.git > - $ mkdir -p llvm-project/llvm/build/install > + $ mkdir -p llvm-project/llvm/build > $ cd llvm-project/llvm/build > $ cmake .. -G "Ninja" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \ > -DLLVM_ENABLE_PROJECTS="clang" \ > - -DBUILD_SHARED_LIBS=OFF \ > -DCMAKE_BUILD_TYPE=Release \ > -DLLVM_BUILD_RUNTIME=OFF > $ ninja > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile > index 26fc96c..d061446 100644 > --- a/samples/bpf/Makefile > +++ b/samples/bpf/Makefile > @@ -208,7 +208,7 @@ TPROGLDLIBS_xdpsock += -pthread -lcap > TPROGLDLIBS_xsk_fwd += -pthread > > # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline: > -# make M=samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang > +# make M=samples/bpf LLC=~/git/llvm-project/llvm/build/bin/llc CLANG=~/git/llvm-project/llvm/build/bin/clang > LLC ?= llc > CLANG ?= clang > OPT ?= opt > diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst > index dd34b2d..23006cb 100644 > --- a/samples/bpf/README.rst > +++ b/samples/bpf/README.rst > @@ -65,17 +65,19 @@ To generate a smaller llc binary one can use:: > Quick sniplet for manually compiling LLVM and clang > (build dependencies are cmake and gcc-c++):: Technically, ninja is now a build dependency as well, it might be worth mentioning that here (usually the package is ninja or ninja-build). Regardless of whether that is addressed or not (because it is small), feel free to carry forward my tag in any future revisions unless they drastically change. > - $ git clone http://llvm.org/git/llvm.git > - $ cd llvm/tools > - $ git clone --depth 1 http://llvm.org/git/clang.git > - $ cd ..; mkdir build; cd build > - $ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86" > - $ make -j $(getconf _NPROCESSORS_ONLN) > + $ git clone https://github.com/llvm/llvm-project.git > + $ mkdir -p llvm-project/llvm/build > + $ cd llvm-project/llvm/build > + $ cmake .. -G "Ninja" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \ > + -DLLVM_ENABLE_PROJECTS="clang" \ > + -DCMAKE_BUILD_TYPE=Release \ > + -DLLVM_BUILD_RUNTIME=OFF > + $ ninja > > It is also possible to point make to the newly compiled 'llc' or > 'clang' command via redefining LLC or CLANG on the make command line:: > > - make M=samples/bpf LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang > + make M=samples/bpf LLC=~/git/llvm-project/llvm/build/bin/llc CLANG=~/git/llvm-project/llvm/build/bin/clang > > Cross compiling samples > ----------------------- > -- > 2.1.0 >
