On Thu, Jan 21, 2021 at 12:08:31AM -0800, Andrii Nakryiko wrote: > On Wed, Jan 20, 2021 at 9:36 PM Nathan Chancellor > <natechancellor@xxxxxxxxx> wrote: > > > > 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 out of date.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). > > it's possible to generate Makefile by passing `-g "Unix Makefiles"`, > which would avoid dependency on ninja, no? Yes, although I am fairly certain that building with ninja is quicker so I would recommend keeping it. One small extra dependency never killed anyone plus ninja is becoming more common nowadays :) > > 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 > > >
