[PATCH v2 1/1] kbuild: deb-pkg: Build parallely with current dpkg-buildpackage

[Bastian Germann <bage@linutronix.de>]

With dpkg-buildpackage v1.21.10 or later, the only way to build the
deb-pkg generated package parallely is adding -j<N> to the MAKEFLAGS
environment variable or using the --jobs-force option. The package ignores
the usual parallel build option that is described in Debian Policy §4.9.1.

Derive make's -j parameter from the DEB_BUILD_OPTIONS environment variable
that ends up being set by dpkg-buildpackage -j<N>.

Link: https://www.debian.org/doc/debian-policy/ch-source.html
Signed-off-by: Bastian Germann <bage@linutronix.de>
---
 scripts/package/mkdebian | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
index f74380036bb5..0217790e7a26 100755
--- a/scripts/package/mkdebian
+++ b/scripts/package/mkdebian
@@ -238,11 +238,15 @@ fi
 cat <<EOF > debian/rules
 #!$(command -v $MAKE) -f
 
+ifneq (,\$(filter parallel=%,\$(DEB_BUILD_OPTIONS)))
+	JOBS = -j\$(subst parallel=,,\$(filter parallel=%,\$(DEB_BUILD_OPTIONS)))
+endif
+
 srctree ?= .
 
 build-indep:
 build-arch:
-	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} \
+	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} \$(JOBS) \
 	\$(shell \$(srctree)/scripts/package/deb-build-option) \
 	olddefconfig all
 
@@ -250,10 +254,10 @@ build: build-arch
 
 binary-indep:
 binary-arch: build-arch
-	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} intdeb-pkg
+	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} \$(JOBS) intdeb-pkg
 clean:
 	rm -rf debian/files debian/linux-*
-	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} clean
+	\$(MAKE) -f \$(srctree)/Makefile ARCH=${ARCH} \$(JOBS) clean
 
 binary: binary-arch
 EOF
-- 
2.39.2