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XBDBACK(4)            NetBSD/xen Kernel Interfaces Manual           XBDBACK(4)


NAME

     xbdback -- Xen backend paravirtualized block device interface


SYNOPSIS

     pseudo-device xbdback


DESCRIPTION

     The xbdback interface forms the backend part of the paravirtualized driv-
     ers used by Xen domains to offer a block device interface, similar to a
     hard disk.  xbdback interfaces are backed either by a physical device
     directly, or an image file mounted through vnd(4).

     All xbdback interfaces follow the ``xbdbackXiY'' naming convention, where
     `X' represents the guest domain identifier, and `Y' an arbitrary identi-
     fier.  This identifier is usually associated to the device node as seen
     by the guest using major(3) and minor(3) numbers.  For example, identi-
     fier ``769'' (0x301) means major 3 and minor 1, identified as ``hda1''
     under Linux convention.  For NetBSD, the guest device name specified in
     the guest configuration file does not matter, and can be chosen arbitrar-
     ily.

     A xbdback interface will appear as a xbd(4) block device inside a NetBSD
     guest domain.  In the XenStore, xbd and xbdback are identified by ``vbd''
     (virtual block device) entries.


DIAGNOSTICS

     xbd backend: attach device %s (size %d) for domain %d  Gives the device
     used as xbdback interface for the given guest domain, and its size, in
     bytes.

     xbd backend 0x%x for domain %d using event channel %d, protocol %s  Gives
     the backend identifier, guest domain ID, event channel ID, and protocol
     used for block level communication.

     xbdback %s: can't VOP_OPEN device 0x%x: %d  When this message appears in
     the system message buffer with error 16 (EBUSY), the device is likely to
     be already mounted.  It must be unmounted first, as the system will
     refuse to open it a second time.


SEE ALSO

     vnd(4), xbd(4), xenbus(4)


HISTORY

     The xbdback driver first appeared in NetBSD 4.0.


AUTHORS

     The xbdback driver was written by Manuel Bouyer <bouyer@NetBSD.org>.

NetBSD 9.3                       June 7, 2011                       NetBSD 9.3