common.sh: add arm64 chroot utility functions

By copying and removing the relevant qemu static executable the
functions enable and disable the chroot environment for arm64 rootfs.

Signed-off-by: Andrej Rosano <andrej@inversepath.com>

common.sh

@@ -992,3 +992,36 @@ BOAT
   echo -e "${V_VIDOFF}"
   die "$* failed"
 }
+
+# The binfmt_misc support in the kernel is required.
+# The aarch64 binaries should be executed through
+# "/usr/bin/qemu-aarch64-static"
+setup_qemu_static() {
+  local root_fs_dir="$1"
+  case "${BOARD}" in
+    amd64-usr) return 0;;
+    arm64-usr)
+      if [[ -f "${root_fs_dir}/sbin/ldconfig" ]]; then
+        sudo cp /usr/bin/qemu-aarch64 "${root_fs_dir}"/usr/bin/qemu-aarch64-static
+      else
+        die "Missing basic layout in target rootfs"
+      fi
+    ;;
+    *) die "Unsupported arch" ;;
+  esac
+}
+
+clean_qemu_static() {
+  local root_fs_dir="$1"
+  case "${BOARD}" in
+    amd64-usr) return 0;;
+    arm64-usr)
+      if [[ -f "${root_fs_dir}/usr/bin/qemu-aarch64-static" ]]; then
+        sudo rm "${root_fs_dir}"/usr/bin/qemu-aarch64-static
+      else
+        die "File not found"
+      fi
+    ;;
+    *) die "Unsupported arch" ;;
+  esac
+}