x86_64: initial support for PARTUUID

This change configures grub to mount the rootfs by PARTUUID instead of the
device path if CONFIG_TARGET_ROOTFS_PARTNAME is unset.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

SVN-Revision: 42936

target/linux/x86_64/image/Makefile

@@ -40,7 +40,9 @@ ifneq ($(GRUB_TERMINALS),)
   GRUB_TERMINAL_CONFIG := terminal_input $(GRUB_TERMINALS); terminal_output $(GRUB_TERMINALS)
 endif
 
+SIGNATURE:=$(shell dd if=/dev/urandom bs=4 count=1 2>/dev/null | hexdump -v -e '"%02x"')
 ROOTPART:=$(call qstrip,$(CONFIG_TARGET_ROOTFS_PARTNAME))
+ROOTPART:=$(if $(ROOTPART),$(ROOTPART),PARTUUID=$(SIGNATURE)-02)
 
 GRUB_TIMEOUT:=$(call qstrip,$(CONFIG_GRUB_TIMEOUT))
 
@@ -82,7 +84,7 @@ ifneq ($(CONFIG_GRUB_IMAGES),)
 		-e 's#@CMDLINE@#$(strip $(call Image/cmdline/$(1)) $(BOOTOPTS) $(GRUB_CONSOLE_CMDLINE))#g' \
 		-e 's#@TIMEOUT@#$(GRUB_TIMEOUT)#g' \
 		./grub.cfg > $(KDIR)/root.grub/boot/grub/grub.cfg
-	PADDING="$(CONFIG_TARGET_IMAGES_PAD)" PATH="$(TARGET_PATH)" ./gen_image_generic.sh \
+	PADDING="$(CONFIG_TARGET_IMAGES_PAD)" SIGNATURE="$(SIGNATURE)" PATH="$(TARGET_PATH)" ./gen_image_generic.sh \
 		$(BIN_DIR)/$(IMG_PREFIX)-combined-$(1).img \
 		$(CONFIG_TARGET_KERNEL_PARTSIZE) $(KDIR)/root.grub \
 		$(CONFIG_TARGET_ROOTFS_PARTSIZE) $(KDIR)/root.$(1) \

target/linux/x86_64/image/gen_image_generic.sh

@@ -20,7 +20,7 @@ sect=63
 cyl=$(( ($KERNELSIZE + $ROOTFSSIZE) * 1024 * 1024 / ($head * $sect * 512)))
 
 # create partition table
-set `ptgen -o "$OUTPUT" -h $head -s $sect -p ${KERNELSIZE}m -p ${ROOTFSSIZE}m ${ALIGN:+-l $ALIGN}`
+set `ptgen -o "$OUTPUT" -h $head -s $sect -p ${KERNELSIZE}m -p ${ROOTFSSIZE}m ${ALIGN:+-l $ALIGN} ${SIGNATURE:+-S 0x$SIGNATURE}`
 
 KERNELOFFSET="$(($1 / 512))"
 KERNELSIZE="$(($2 / 512))"