libxl: postpone backend name resolution

This adds a backend_domname field in libxl devices that contain a
backend_domid field, allowing either a domid or a domain name to be
specified in the configuration structures.  The domain name is resolved
into a domain ID in the _setdefault function when adding the device.
This change allows the backend of the block devices to be specified
(which previously required passing the libxl_ctx down into the block
device parser), and will simplify specification of backend domains in
other users of libxl.

The check on run_hotplug_scripts in parse_config_data is removed because
it is a duplicate of the one in libxl__device_nic_setdefault, and is
removed here because it no longer has the resolved domain ID to check.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
[ ijc -- reran flex ]

1 files changed, 12 insertions, 0 deletions

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 92f3f8ee0b..25efa76a04 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -296,6 +296,18 @@
  */
 #define LIBXL_HAVE_BUILDINFO_USBDEVICE_LIST 1
 
+/*
+ * LIBXL_HAVE_DEVICE_BACKEND_DOMNAME
+ *
+ * If this is defined, libxl_device_* structures containing a backend_domid
+ * field also contain a backend_domname field.  If backend_domname is set, it is
+ * resolved to a domain ID when the device is used and takes precedence over the
+ * backend_domid field.
+ *
+ * If this is not defined, the backend_domname field does not exist.
+ */
+#define LIBXL_HAVE_DEVICE_BACKEND_DOMNAME 1
+
 /* Functions annotated with LIBXL_EXTERNAL_CALLERS_ONLY may not be
  * called from within libxl itself. Callers outside libxl, who
  * do not #include libxl_internal.h, are fine. */