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
(cherry picked from commit 567779e51a)
This commit is contained in:
Jim Fehlig 2013-02-20 13:02:28 -07:00 committed by Eric Blake
parent 96a49bd8bb
commit e91f69ed89

View File

@ -547,9 +547,13 @@ libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_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? */