docs: Makefile: Inherit PYTHONPYCACHEPREFIX setting as env variable

Commit 6c2f0b28d76e ("docs: Makefile: store __pycache__ at the output
directory") assigns a new path to PYTHONPYCACHEPREFIX for building
kernel documentation.

However, it is not necessarily optimal for everyone.

If you find PYTHONPYCACHEPREFIX is already set, it strongly suggests
that the developer has selected the setting as best suited for one's own
workflow.

Use "?=" in the assignment to PYTHONPYCACHEPREFIX so that the path of
$(abspath $(BUILDDIR)/__pycache__) works only as a safeguard.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <0253ce98-960c-4498-8ace-a4354e3ebc26@gmail.com>

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 59e95ebae786c6abf0cb972c4712ae7c9135957d..d30d66ddf1ada5b7921cb45f2c0d8454fd3c523d 100644 (file)
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -82,9 +82,11 @@ loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit;
 # $5 reST source folder relative to $(src),
 #    e.g. "userspace-api/media" for the linux-tv book-set at ./Documentation/userspace-api/media
 
+PYTHONPYCACHEPREFIX ?= $(abspath $(BUILDDIR)/__pycache__)
+
 quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
       cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/userspace-api/media $2 && \
-       PYTHONPYCACHEPREFIX=$(abspath $(BUILDDIR)/__pycache__) \
+       PYTHONPYCACHEPREFIX="$(PYTHONPYCACHEPREFIX)" \
        BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(src)/$5/$(SPHINX_CONF)) \
        $(PYTHON3) $(srctree)/scripts/jobserver-exec \
        $(CONFIG_SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \