File 567779e5-libxl-default-disk-backend.patch of Package libvirt

commit 567779e51a7727b021dee095c9d75cf0cde0bd43
Author: Jim Fehlig <jfehlig@suse.com>
Date:   Wed Feb 20 13:02:28 2013 -0700

    libxl: Fix setting of disk backend
    
    The libxl driver was setting the backend field of libxl_device_disk
    structure to LIBXL_DISK_BACKEND_TAP when the driver element of disk
    configuration was not specified.  This needlessly forces the use of
    blktap driver, which may not be loaded in dom0
    
    https://bugzilla.redhat.com/show_bug.cgi?id=912488
    
    Ian Campbell suggested that LIBXL_DISK_BACKEND_UNKNOWN is a better
    default in this case
    
    https://www.redhat.com/archives/libvir-list/2013-February/msg01126.html

Index: libvirt-1.0.2/src/libxl/libxl_conf.c
===================================================================
--- libvirt-1.0.2.orig/src/libxl/libxl_conf.c
+++ libvirt-1.0.2/src/libxl/libxl_conf.c
@@ -525,9 +525,13 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk
             return -1;
         }
     } else {
-        /* No driverName - default to raw/tap?? */
+        /*
+         * If driverName is not specified, default to raw as per
+         * xl-disk-configuration.txt in the xen documentation and let
+         * libxl pick a suitable backend.
+         */
         x_disk->format = LIBXL_DISK_FORMAT_RAW;
-        x_disk->backend = LIBXL_DISK_BACKEND_TAP;
+        x_disk->backend = LIBXL_DISK_BACKEND_UNKNOWN;
     }
 
     /* XXX is this right? */