[OpenWrt-Devel] [PATCH] x86: use PARTUUID instead explicitly specifying the device by default

[Matthias Schiffer]

This changes the x86 image generation to match x86_64, using the PARTUUID for
the rootfs instead of explicitly configuring the device.

This unbreaks KVM with VirtIO, which uses /dev/vda2 instead of /dev/sda2.

Tested in QEMU/KVM with VirtIO, VirtualBox and VMware.

Signed-off-by: Matthias Schiffer <mschiffer at universe-factory.net>
---
 config/Config-images.in                     | 2 --
 target/linux/x86/image/Makefile             | 4 +++-
 target/linux/x86/image/gen_image_generic.sh | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/config/Config-images.in b/config/Config-images.in
index 5c2e79e..a420c39 100644
--- a/config/Config-images.in
+++ b/config/Config-images.in
@@ -267,8 +267,6 @@ menu "Target Images"
 	config TARGET_ROOTFS_PARTNAME
 		string "Root partition on target device"
 		depends on OLPC_BOOTSCRIPT_IMAGES || GRUB_IMAGES
-		default "/dev/xvda2" if TARGET_x86_xen_domu
-		default "/dev/sda2" if TARGET_x86 && ! TARGET_x86_xen_domu
 		help
 		  Override the root partition on the final device. If left empty,
 		  it will be mounted by PARTUUID which makes the kernel find the
diff --git a/target/linux/x86/image/Makefile b/target/linux/x86/image/Makefile
index 5983718..a0045a7 100644
--- a/target/linux/x86/image/Makefile
+++ b/target/linux/x86/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) \
diff --git a/target/linux/x86/image/gen_image_generic.sh b/target/linux/x86/image/gen_image_generic.sh
index 9d11efb..3fb31f6 100755
--- a/target/linux/x86/image/gen_image_generic.sh
+++ b/target/linux/x86/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))"
-- 
2.3.2
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