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authorIvan Khoronzhuk <ivan.khoronzhuk@linaro.org>2019-10-11 03:28:08 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-10-12 16:09:00 -0700
commit1600c9c26f6bbdd29fb1b44f13fb751846d2ebe8 (patch)
tree8dc76784476e53cfbd5465a509d107be5e5717f0 /samples
parentb2327c107d6255e4ea591042120514bedcdc616a (diff)
downloadlinux-1600c9c26f6bbdd29fb1b44f13fb751846d2ebe8.tar.bz2
samples/bpf: Add preparation steps and sysroot info to readme
Add couple preparation steps: clean and configuration. Also add newly added sysroot support info to cross-compile section. Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191011002808.28206-16-ivan.khoronzhuk@linaro.org
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/README.rst41
1 files changed, 36 insertions, 5 deletions
diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst
index 5f27e4faca50..cc1f00a1ee06 100644
--- a/samples/bpf/README.rst
+++ b/samples/bpf/README.rst
@@ -14,6 +14,20 @@ Compiling requires having installed:
Note that LLVM's tool 'llc' must support target 'bpf', list version
and supported targets with command: ``llc --version``
+Clean and configuration
+-----------------------
+
+It can be needed to clean tools, samples or kernel before trying new arch or
+after some changes (on demand)::
+
+ make -C tools clean
+ make -C samples/bpf clean
+ make clean
+
+Configure kernel, defconfig for instance::
+
+ make defconfig
+
Kernel headers
--------------
@@ -68,9 +82,26 @@ It is also possible to point make to the newly compiled 'llc' or
Cross compiling samples
-----------------------
In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
-environment variables before calling make. This will direct make to build
-samples for the cross target.
+environment variables before calling make. But do this before clean,
+cofiguration and header install steps described above. This will direct make to
+build samples for the cross target::
+
+ export ARCH=arm64
+ export CROSS_COMPILE="aarch64-linux-gnu-"
+
+Headers can be also installed on RFS of target board if need to keep them in
+sync (not necessarily and it creates a local "usr/include" directory also)::
+
+ make INSTALL_HDR_PATH=~/some_sysroot/usr headers_install
+
+Pointing LLC and CLANG is not necessarily if it's installed on HOST and have
+in its targets appropriate arm64 arch (usually it has several arches).
+Build samples::
+
+ make samples/bpf/
+
+Or build samples with SYSROOT if some header or library is absent in toolchain,
+say libelf, providing address to file system containing headers and libs,
+can be RFS of target board::
-export ARCH=arm64
-export CROSS_COMPILE="aarch64-linux-gnu-"
-make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
+ make samples/bpf/ SYSROOT=~/some_sysroot