libxl: disks: allow specification of "backendtype=phy|tap|qdisk"

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/docs/misc/xl-disk-configuration.txt b/docs/misc/xl-disk-configuration.txt
index de0a75e1bc..91e0cc7284 100644
--- a/docs/misc/xl-disk-configuration.txt
+++ b/docs/misc/xl-disk-configuration.txt
@@ -139,6 +139,23 @@ cdrom
 Convenience alias for "devtype=cdrom".
 
 
+backendtype=<backend-type>
+--------------------------
+
+Description:           Specifies the backend implementation to use
+Supported values:      phy, tap, qdisk
+Mandatory:             No
+Default value:         Automatically determine which backend to use.
+
+This does not affect the guest's view of the device.  It controls
+which software implementation of the Xen backend driver us used.
+
+Not all backend drivers support all combinations of other options.
+For example, "phy" does not support formats other than "raw".
+Normally this option should not be specified, in which case libxl will
+automatically determine the most suitable backend.
+
+
 script=<script>
 ---------------