On Sat, Jan 30, 2021 at 9:15 AM Jonathan Corbet [off-list ref] wrote:

Noa Sakurajin [off-list ref] writes:

[CC += kbuild maintainers]

quoted

 Before the command python was needed for the documentation to build.
 This patch checks if python is available and uses python3 as
 fallback.

 This is needed because a lot of distribution (at least Ubuntu)
 only provide python3 and not python. scripts/sphinx-pre-install
 checks for python3 first and does not check if python exists
 which causes it to report that everything is installed even
 if the documentation build failed.

Signed-off-by: Noa Sakurajin <redacted>
---
 Documentation/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 61a7310b49e0..8a4a7df3b74a 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile

@@ -75,7 +75,8 @@ quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
       cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/userspace-api/media $2 && \
      PYTHONDONTWRITEBYTECODE=1 \
      BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
-     $(PYTHON) $(srctree)/scripts/jobserver-exec \
+     PY=$(shell command -v $(PYTHON) 2> /dev/null) \
+     $${PY:-"$(PYTHON3)"} $(srctree)/scripts/jobserver-exec \

So I see what you're trying to do, and we definitely want this to work.
I susped this isn't the right fix, though; it could leave us open to
similar issues elsewhere in the tree.

Personally, I think that $(PYTHON) should get a working Python if it's
installed, so I would suggest fixing the top-level Makefile to set it
correctly.  Masahiro, thoughts on that?

Alternatively, we could just say $(PYTHON3) and explicitly leave Python2
behind; that needs to happen in the not-too-distant future regardless
but we haven't decided to actually do it yet.

We are already doing this in linux-next.

I will apply this.
https://lore.kernel.org/patchwork/patch/1373422/

Thanks,

jon

-- 
Best Regards
Masahiro Yamada