diff options
| author | Tiezhu Yang <yangtiezhu@loongson.cn> | 2021-01-22 09:39:44 +0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-01-23 00:09:03 +0100 |
| commit | 628add78b07ad05ad005f1909dfc3c91e195ac23 (patch) | |
| tree | 3dfcf7b4ea410419a0ca483bc10a544175d96634 /samples | |
| parent | 443edcefb8213155c0da22c4a999f4a49858fa39 (diff) | |
bpf, docs: Update build procedure for manually compiling LLVM and Clang
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out of date.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.
At last, we recommend that developers who want the fastest incremental
builds use the Ninja build system [1], you can find it in your system's
package manager, usually the package is ninja or ninja-build [3], so add
ninja to build dependencies suggested by Nathan.
[1] https://clang.llvm.org/get_started.html
[2] https://www.llvm.org/docs/CMake.html
[3] https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Cc: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/bpf/1611279584-26047-1-git-send-email-yangtiezhu@loongson.cn
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/bpf/Makefile | 2 | ||||
| -rw-r--r-- | samples/bpf/README.rst | 22 |
2 files changed, 15 insertions, 9 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 26fc96ca619e..d06144613ca2 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 dd34b2d26f1c..60c6494adb1b 100644 --- a/samples/bpf/README.rst +++ b/samples/bpf/README.rst @@ -62,20 +62,26 @@ To generate a smaller llc binary one can use:: -DLLVM_TARGETS_TO_BUILD="BPF" +We recommend that developers who want the fastest incremental builds +use the Ninja build system, you can find it in your system's package +manager, usually the package is ninja or ninja-build. + Quick sniplet for manually compiling LLVM and clang -(build dependencies are cmake and gcc-c++):: +(build dependencies are ninja, cmake and gcc-c++):: - $ 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 ----------------------- |