Some changes to be able to build an armel-based rootfs.

src/scripts/build_image.sh

Index: src/scripts/build_image.sh
diff --git a/src/scripts/build_image.sh b/src/scripts/build_image.sh
index 6c6f9bc2be87c3a04766e088a68e0d1763826c64..982c6035e8fcce255e682e901fcc7f99fb3111c4 100755
--- a/src/scripts/build_image.sh
+++ b/src/scripts/build_image.sh
@@ -142,15 +142,16 @@ fi
 
 # -- Turn root file system into bootable image --
 
-# Setup extlinux configuration.
-# TODO: For some reason the /dev/disk/by-uuid is not being generated by udev
-# in the initramfs. When we figure that out, switch to root=UUID=$UUID.
-cat <<EOF | sudo dd of="$ROOT_FS_DIR"/boot/extlinux.conf
+if [ "$FLAGS_arch" = "x86" ]; then
+  # Setup extlinux configuration.
+  # TODO: For some reason the /dev/disk/by-uuid is not being generated by udev
+  # in the initramfs. When we figure that out, switch to root=UUID=$UUID.
+  cat <<EOF | sudo dd of="$ROOT_FS_DIR"/boot/extlinux.conf
 DEFAULT chromeos-usb
 PROMPT 0
 TIMEOUT 0
 
-label chromeos-usb
+  label chromeos-usb
   menu label chromeos-usb
   kernel vmlinuz
   append quiet console=tty2 initrd=initrd.img init=/sbin/init boot=local rootwait root=LABEL=$DISK_LABEL ro noresume noswap i915.modeset=1 loglevel=1
@@ -164,22 +165,28 @@ EOF
 # Make partition bootable and label it.
 sudo "$SCRIPTS_DIR/extlinux.sh" -z --install "${ROOT_FS_DIR}/boot"
 
+fi  # --arch=x86
+
 cleanup_rootfs_loop
 
+if [ "$FLAGS_arch" = "x86" ]; then
+
 # Create a master boot record.
 # Start with the syslinux master boot record. We need to zero-pad to
 # fill out a 512-byte sector size.
-SYSLINUX_MBR="/usr/lib/syslinux/mbr.bin"
-dd if="$SYSLINUX_MBR" of="$MBR_IMG" bs=512 count=1 conv=sync
-# Create a partition table in the MBR.
-NUM_SECTORS=$((`stat --format="%s" "$ROOT_FS_IMG"` / 512))
-sudo sfdisk -H64 -S32 -uS -f "$MBR_IMG" <<EOF
+  SYSLINUX_MBR="/usr/lib/syslinux/mbr.bin"
+  dd if="$SYSLINUX_MBR" of="$MBR_IMG" bs=512 count=1 conv=sync
+  # Create a partition table in the MBR.
+  NUM_SECTORS=$((`stat --format="%s" "$ROOT_FS_IMG"` / 512))
+  sudo sfdisk -H64 -S32 -uS -f "$MBR_IMG" <<EOF
 ,$NUM_SECTORS,L,-,
 ,$NUM_SECTORS,S,-,
 ,$NUM_SECTORS,L,*,
 ;
 EOF
 
+fi  # --arch=x86
+
 OUTSIDE_OUTPUT_DIR="${EXTERNAL_TRUNK_PATH}/src/build/images/${IMAGE_SUBDIR}"
 echo "Done.  Image created in ${OUTPUT_DIR}"
 echo "To copy to USB keyfob, outside the chroot, do something like:"