From a6328f7c2b7cd8322f57d8e7802fd227d9abc514 Mon Sep 17 00:00:00 2001
From: Michael Marineau <michael.marineau@coreos.com>
Date: Thu, 27 Mar 2014 15:41:41 -0700
Subject: [PATCH] feat(vm_image_util): Add /usr/.noupdate flag file in PXE
 images.

This can be used by update_engine as a quick test to determine if it is
running on a system that it can handle. This avoids needing something
like the 'coreos.diskless' kernel command line flag.
---
 build_library/vm_image_util.sh | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/build_library/vm_image_util.sh b/build_library/vm_image_util.sh
index 2623ebc044..5b789504ad 100644
--- a/build_library/vm_image_util.sh
+++ b/build_library/vm_image_util.sh
@@ -301,6 +301,9 @@ _write_cpio_disk() {
 ${squashfs} /sysroot squashfs x-initrd.mount 0 0
 tmpfs /sysroot/usr/share/oem tmpfs size=0,mode=755,x-initrd.mount 0 0
 EOF
+
+        # Inject /usr/.noupdate into squashfs to disable update_engine
+        echo "/usr/.noupdate f 444 root root echo -n" >"${VM_TMP_DIR}/extra"
     else
         # Set tmpfs as default root, squashfs as default /usr
         sudo_clobber "${cpio_target}/etc/fstab" <<EOF
@@ -320,11 +323,14 @@ users:
     passwd: $(</etc/shared_user_passwd.txt)
 EOF
         fi
+
+        # Inject /usr/.noupdate into squashfs to disable update_engine
+        echo "/.noupdate f 444 root root echo -n" >"${VM_TMP_DIR}/extra"
     fi
 
     # Build the squashfs, embed squashfs into a gzipped cpio
     pushd "${cpio_target}" >/dev/null
-    sudo mksquashfs "${base_dir}" "./${squashfs}"
+    sudo mksquashfs "${base_dir}" "./${squashfs}" -pf "${VM_TMP_DIR}/extra"
     find . | cpio -o -H newc | gzip > "$2"
     popd >/dev/null