allow the creation of ova images

requires open-vmdk, a gentoo ebuild is available here:
https://git.unitas-network.de/Gentoo/unitas-misc/src/branch/master/app-emulation/open-vmdk

Makefile

@@ -10,6 +10,9 @@ RAW_IMAGE = $(IMAGES)/$(APPLIANCE).img
 QCOW_IMAGE = $(IMAGES)/$(APPLIANCE).qcow
 VMDK_IMAGE = $(IMAGES)/$(APPLIANCE).vmdk
 VMDK_TYPE = IDE
+OVA_IMAGE = $(IMAGES)/$(APPLIANCE).ova
+OVA_NUM_CPUS = 1
+OVA_MEM_SIZE = 1024
 XVA_IMAGE = $(IMAGES)/$(APPLIANCE).xva
 LST_FILE = $(IMAGES)/$(APPLIANCE)-packages.lst
 CHECKSUMS = $(IMAGES)/SHA256SUMS
@@ -312,6 +315,16 @@ endif
 
 vmdk: $(VMDK_IMAGE)
 
+NUM_CPUS := $(OVA_NUM_CPUS)
+MEM_SIZE := $(OVA_MEM_SIZE)
+export NUM_CPUS MEM_SIZE
+
+$(OVA_IMAGE): $(VMDK_IMAGE)
+	@print Creating `basename $(OVA_IMAGE)`
+	cd $(IMAGES) && mkova.sh $(APPLIANCE) $(VMDK_IMAGE) /usr/share/open-vmdk/template.ovf
+
+ova: $(OVA_IMAGE)
+
 $(STAGE4_TARBALL): $(PORTAGE_DIR) stage3-$(VA_ARCH).tar.xz appliances/$(APPLIANCE) configs/rsync-excludes
 	$(MAKE) $(STAGE3)
 	$(MAKE) $(PREPROOT)
@@ -380,6 +393,7 @@ help:
 	@echo 'image                    - Build a raw VM image from stage4'
 	@echo 'qcow                     - Build a qcow VM image from a raw image'
 	@echo 'vmdk                     - Build a vmdk image from a raw image'
+	@echo 'ova                      - Build a  ova image from a vmdk image'
 	@echo 'xva                      - Build an xva image from a raw image'
 	@echo 'appliance-list           - List built-in appliances'
 	@echo 'help                     - Show this help'
@@ -400,4 +414,4 @@ help:
 	@print 'Example to build the base appliance'
 	@echo 'make APPLIANCE=base HEADLESS=YES VIRTIO=YES stage4 qcow clean'
 
-.PHONY: qcow vmdk clean realclean distclean stage4 image stage4 help appliance-list eclean sync_portage sync_stage3 checksums
+.PHONY: qcow vmdk ova clean realclean distclean stage4 image stage4 help appliance-list eclean sync_portage sync_stage3 checksums