On 01/20/2021 10:43 AM, Nick Desaulniers wrote:
On Mon, Jan 18, 2021 at 11:56 PM Tiezhu Yang <yangtie...@loongson.cn> wrote:
The current llvm/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out of date.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/clang, the Clang Getting Started page [1] has
one way. As Yonghong said, it is better to just 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.
[1] https://clang.llvm.org/get_started.html
There's also
https://www.kernel.org/doc/html/latest/kbuild/llvm.html#getting-llvm
(could cross link in rst/sphinx).
Signed-off-by: Tiezhu Yang <yangtie...@loongson.cn>
Acked-by: Yonghong Song <y...@fb.com>
---
v2: Update the commit message suggested by Yonghong,
thank you very much.
samples/bpf/Makefile | 2 +-
samples/bpf/README.rst | 17 ++++++++++-------
2 files changed, 11 insertions(+), 8 deletions(-)
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..d1be438 100644
--- a/samples/bpf/README.rst
+++ b/samples/bpf/README.rst
@@ -65,17 +65,20 @@ To generate a smaller llc binary one can use::
Quick sniplet for manually compiling LLVM and clang
(build dependencies are 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"
Is the BPF target not yet on by default?
The default value includes BPF.
I frown upon disabling other backends.
I think the initial aim of the build procedure in samples/bpf/README.rst [1]
is a simple and quick start guide:
[ To generate a smaller llc binary one can use:
-DLLVM_TARGETS_TO_BUILD="BPF" ]
[1] https://github.com/torvalds/linux/blob/master/samples/bpf/README.rst
- $ make -j $(getconf _NPROCESSORS_ONLN)
+ $ git clone https://github.com/llvm/llvm-project.git
+ $ mkdir -p llvm-project/llvm/build/install
+ $ 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
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
--
You received this message because you are subscribed to the Google Groups "Clang
Built Linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to clang-built-linux+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/clang-built-linux/1611042978-21473-1-git-send-email-yangtiezhu%40loongson.cn.
