xen/build: disable default built-in rules and variables

Disable the built-in rules and variables from GNU make to improve
build performance and avoid awkward corner cases with the built-in
rules. Currently none of the implicit rules are used but this is helpful
to do when developing changes to the build system.

Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/Makefile b/xen/Makefile
index fa9cf0a62be833d11edfc4254708093fca66e216..3a1de99532b81fa03cb9dac8a13fdb79e43ae886 100644 (file)
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -15,6 +15,9 @@ export XEN_BUILD_HOST ?= $(shell hostname)
 export BASEDIR := $(CURDIR)
 export XEN_ROOT := $(BASEDIR)/..
 
+# Do not use make's built-in rules and variables
+MAKEFLAGS += -rR
+
 EFI_MOUNTPOINT ?= $(BOOT_DIR)/efi
 
 .PHONY: default