File 48d81cef-libxl-qdisk.patch of Package libvirt

commit 48d81cef3b2dff6fe02bd7c8f0bf4f5aff917d8c
Author: Jim Fehlig <jfehlig@suse.com>
Date:   Thu Jun 19 23:36:25 2014 -0600

    libxl: prefer qdisk for <driver name='file'>
    
    The libxl driver currently sets the disk backend to
    LIBXL_DISK_BACKEND_TAP when <driver name='file'> is specified
    in the <disk> config.  qdisk should be prefered with this
    configuration, otherwise existing configuration such as the
    following, which worked with the old Xen driver, will not work
    with the libxl driver
    
      <disk type='file' device='cdrom'>
        <driver name='file'/>
        <source file='/path/to/some/iso'/>
        <target dev='hdc' bus='ide'/>
        <readonly/>
      </disk>
    
    In addition, tap performs poorly compared to qdisk.

Index: libvirt-1.2.5/src/libxl/libxl_conf.c
===================================================================
--- libvirt-1.2.5.orig/src/libxl/libxl_conf.c
+++ libvirt-1.2.5/src/libxl/libxl_conf.c
@@ -794,7 +794,7 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk
                 return -1;
             }
             x_disk->format = LIBXL_DISK_FORMAT_RAW;
-            x_disk->backend = LIBXL_DISK_BACKEND_TAP;
+            x_disk->backend = LIBXL_DISK_BACKEND_QDISK;
         } else if (STREQ(driver, "phy")) {
             if (format != VIR_STORAGE_FILE_NONE &&
                 format != VIR_STORAGE_FILE_RAW) {