Manual browser: xbd(4)

XBD(4) Kernel Interfaces Manual (Xen) XBD(4)


xbdXen frontend paravirtualized block device interface


xbd* at xenbus?


The xbd interface forms the frontend part of the paravirtualized drivers used by Xen guest domains to have a block device interface.

From a guest point of view, xbd is similar to a hard disk, and can be treated in the very same way regarding partitioning, file systems creation and usage, and mounting. By default, a NetBSD guest domain will assume that “xbd0a” serves as the root file system.

When the host is NetBSD, the xbd interface is backed by a xbdback(4) interface. In the XenStore, xbd and xbdback are identified by “vbd” (virtual block device) entries.


xbd%d: using event channel %d
Specifies the event channel used by this xbd interface.
xbd%d: %s MB, %d bytes/sect x %u sectors
Gives the total size of the xbd block device, its sector size and total number of sectors.
xbd%d: WARNING: cache flush not supported by backend
The backend driver associated with this xbd device does not support cache flushing operation. This can be problematic for file system operations that require cache sync to avoid data loss or corruption.


The xbd driver first appeared in NetBSD 3.0.


The xbd driver was written by Manuel Bouyer <>.
January 8, 2011 NetBSD 7.0