On Tue, Dec 17, 2024 at 12:10 PM Li Zhijian <lizhijian@xxxxxxxxxxx> wrote:
>
> Fixes an issue where out-of-tree kselftest builds fail when building
> the BPF and bpftools components. The failure occurs because the top-level
> Makefile passes a relative srctree path ('..') to its sub-Makefiles, which
> leads to errors in locating necessary files.
>
> For example, the following error is encountered:
>
> ```
> $ make V=1 O=$build/ TARGETS=hid kselftest-all
> ...
> make -C ../tools/testing/selftests all
> make[4]: Entering directory '/path/to/linux/tools/testing/selftests/hid'
> make -C /path/to/linux/tools/testing/selftests/../../../tools/lib/bpf OUTPUT=/path/to/linux/O/kselftest/hid/tools/build/libbpf/ \
> EXTRA_CFLAGS='-g -O0' \
> DESTDIR=/path/to/linux/O/kselftest/hid/tools prefix= all install_headers
> make[5]: Entering directory '/path/to/linux/tools/lib/bpf'
> ...
> make[5]: Entering directory '/path/to/linux/tools/bpf/bpftool'
> Makefile:127: ../tools/build/Makefile.feature: No such file or directory
> make[5]: *** No rule to make target '../tools/build/Makefile.feature'. Stop.
> ```
>
> To resolve this, the srctree is exported as an absolute path (abs_srctree)
> when performing an out-of-tree build. This ensures that all sub-Makefiles
> have the correct path to the source tree, preventing directory resolution
> errors.
NACK.
This negates 9da0763bdd82572be243fcf5161734f11568960f
This is a recurring topic [1] because kselftest adopts a completely
different build system.
If kselftest cannot do this correctly, please do not hook it to the
top-Makefile.
[1] https://lore.kernel.org/linux-kbuild/cover.1657614127.git.guillaume.tucker@xxxxxxxxxxxxx/
> Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
> ---
> Request for Additional Testing
>
> We welcome all contributors and CI systems to test this change thoroughly.
This is NACKed. I recommend not wasting CI system resources.
> In theory, this change should not affect in-tree builds. However, to ensure
> stability and compatibility, we encourage testing across different
> configurations.
>
> What has been tested?
> - out-of-tree kernel build
> - out-of-tree kselftest-all
> ---
> Makefile | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index e5b8a8832c0c..36e65806bb5e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -275,7 +275,8 @@ else ifeq ($(srcroot)/,$(dir $(CURDIR)))
> srcroot := ..
> endif
>
> -export srctree := $(if $(KBUILD_EXTMOD),$(abs_srctree),$(srcroot))
> +srctree := $(if $(KBUILD_EXTMOD),$(abs_srctree),$(srcroot))
> +export srctree := $(if $(building_out_of_srctree),$(abs_srctree),$(srctree))
>
> ifdef building_out_of_srctree
> export VPATH := $(srcroot)
> --
> 2.44.0
>
>
--
Best Regards
Masahiro Yamada
