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authorTiezhu Yang <yangtiezhu@loongson.cn>2021-01-22 09:39:44 +0800
committerDaniel Borkmann <daniel@iogearbox.net>2021-01-23 00:09:03 +0100
commit628add78b07ad05ad005f1909dfc3c91e195ac23 (patch)
tree3dfcf7b4ea410419a0ca483bc10a544175d96634 /Documentation/bpf
parent443edcefb8213155c0da22c4a999f4a49858fa39 (diff)
downloadlinux-628add78b07ad05ad005f1909dfc3c91e195ac23.tar.bz2
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The current LLVM and Clang build procedure in samples/bpf/README.rst is out of date.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 'Documentation/bpf')
-rw-r--r--Documentation/bpf/bpf_devel_QA.rst11
1 files changed, 7 insertions, 4 deletions
diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst
index 5b613d2a5f1a..2ed89abbf9a4 100644
--- a/Documentation/bpf/bpf_devel_QA.rst
+++ b/Documentation/bpf/bpf_devel_QA.rst
@@ -501,16 +501,19 @@ All LLVM releases can be found at: http://releases.llvm.org/
Q: Got it, so how do I build LLVM manually anyway?
--------------------------------------------------
-A: You need cmake and gcc-c++ as build requisites for LLVM. Once you have
-that set up, proceed with building the latest LLVM and clang version
+A: 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.
+
+You need ninja, cmake and gcc-c++ as build requisites for LLVM. Once you
+have 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