Make deb files reproducible

Author: mpolitzer

build.mk

@@ -47,14 +47,16 @@ cross-deb:  # TARGET == riscv64
 	cat tools/template/cross-control.template | sed 's|ARG_KERNEL_VERSION|$(KERNEL_VERSION)|g' > $(DESTDIR)/DEBIAN/control
 	$(MAKE) -rC $(LINUX_DIR) $(LINUX_OPTS) headers_install \
 		INSTALL_HDR_PATH=$(abspath $(DESTDIR))/usr/riscv64-linux-gnu
-	dpkg-deb -Zxz --root-owner-group --build $(DESTDIR) $(CROSS_DEB_FILENAME)
+	find $(DESTDIR) -exec touch -d "$(KERNEL_TIMESTAMP)" {} \;
+	SOURCE_DATE_EPOCH="1" dpkg-deb -Zxz --root-owner-group --build $(DESTDIR) $(CROSS_DEB_FILENAME)
 
 native-deb: # HOST   == riscv64
 	mkdir -p $(DESTDIR)/DEBIAN
 	cat tools/template/cross-control.template | sed 's|ARG_KERNEL_VERSION|$(KERNEL_VERSION)|g' > $(DESTDIR)/DEBIAN/control
 	$(MAKE) -rC $(LINUX_DIR) $(LINUX_OPTS) headers_install \
 		INSTALL_HDR_PATH=$(abspath $(DESTDIR))/usr
-	dpkg-deb -Zxz --root-owner-group --build $(DESTDIR) $(NATIVE_DEB_FILENAME)
+	find $(DESTDIR) -exec touch -d "$(KERNEL_TIMESTAMP)" {} \;
+	SOURCE_DATE_EPOCH="1" dpkg-deb -Zxz --root-owner-group --build $(DESTDIR) $(NATIVE_DEB_FILENAME)
 
 # configure riscv-pk
 # ------------------------------------------------------------------------------