Merge ~smoser/cloud-init:bug/1379080-fix-xen-kernel-detection into cloud-init:ubuntu/devel

[Scott Moser]

[Dan Watkins (oddbloke)]

review: Needs Fixing

[Scott Moser (smoser)]

comments addressed.

diff --git a/debian/update-grub-legacy-ec2 b/debian/update-grub-legacy-ec2
index 19648f6..cb4e170 100755
--- a/debian/update-grub-legacy-ec2
+++ b/debian/update-grub-legacy-ec2
@@ -1398,8 +1398,23 @@ fi
 
 
 if ! type is_xen_kernel >/dev/null 2>&1; then
+  check_xen_config_for_kernel() {
+    # input is like /boot/vmlinuz-2.6.35-13-virtual
+    # expected config path is /boot/config-2.6.35-13-virtual
+    local kernel="$1" config="" dir="" bname=""
+    dir=${kernel%/*}
+    [ "$dir" = "$kernel"] && dir="."
+    bname=${kernel##*/}
+    config="$dir/config-${bname#*-}"
+    [ -f "$config" ] || return 1
+    grep -q CONFIG_XEN=y "$config"
+  }
+
   is_xen_kernel() {
     # input is like /boot/vmlinuz-2.6.35-13-virtual
+    # return whether or not this kernel is xen bootable.
+    check_xen_config_for_kernel "$1" && return 0
+
     # get the version string out of it.
     local ver_flavor="";
     ver_flavor="${1##*vmlinuz-}"
@@ -1418,6 +1433,9 @@ if ! type is_xen_kernel >/dev/null 2>&1; then
 fi
 
 for kern in /boot/vmlinuz-*; do
+  case "$kern" in
+    *.signed) continue;;
+  esac
   is_xen_kernel "${kern}" &&
     xen_verlist="${xen_verlist} ${kern#/boot/vmlinuz-}"
 done