Start generating a bootable kernel partition as part of build_image

src/scripts/build_image

Index: src/scripts/build_image
diff --git a/src/scripts/build_image b/src/scripts/build_image
index fbad19a4d39cfc1455b83fc10cd97d1c84b8f9d2..7ed1137ade9d18ba215a77d37e870017903588a3 100755
--- a/src/scripts/build_image
+++ b/src/scripts/build_image
@@ -380,11 +380,6 @@ sudo INSTALL_MASK="$INSTALL_MASK" emerge-${BOARD} \
   --root="$ROOT_FS_DIR" --root-deps=rdeps \
   --getbinpkg --usepkg chromeos $EMERGE_JOBS
 
-# Extract the kernel from the root filesystem for use by the GPT image. Legacy
-# BIOS will use the kernel in the rootfs (via syslinux), Chrome OS BIOS will
-# use the kernel partition.
-sudo cp -f "${ROOT_FS_DIR}/boot/vmlinuz" "${OUTPUT_DIR}/vmlinuz.image"
-
 # Create EFI System Partition to boot stock EFI BIOS (but not ChromeOS EFI
 # BIOS). We only need this for x86, but it's simpler and safer to keep the disk
 # images the same for both x86 and ARM.
@@ -421,6 +416,32 @@ menuentry "local image B" {
 
 EOF
 
+# Legacy BIOS will use the kernel in the rootfs (via syslinux), as will
+# standard EFI BIOS (via grub, from the EFI System Partition). Chrome OS BIOS
+# will use a separate signed kernel partition, which we'll create now.
+# FIXME: remove serial output, debugging messages
+cat <<'EOF' > "${OUTPUT_DIR}/config.txt"
+earlyprintk=serial,ttyS0,115200
+console=ttyS0,115200
+init=/sbin/init
+add_efi_memmap
+boot=local
+rootwait
+root=/dev/sd%D%P
+ro
+noresume
+noswap
+i915.modeset=1
+loglevel=7
+Hi_Mom
+EOF
+
+# FIXME: This just creates the image. It doesn't sign it.
+sudo create_blob -o "${OUTPUT_DIR}/vmlinuz.image" \
+  "${ROOT_FS_DIR}/boot/vmlinuz" \
+  "${OUTPUT_DIR}/config.txt" \
+  /lib64/bootstub/bootstub.efi
+
 # Perform any customizations on the root file system that are needed.
 "${SCRIPTS_DIR}/customize_rootfs" \
   --root="$ROOT_FS_DIR" \