xbd(4) [netbsd man page]

XBD(4)							 BSD/xen Kernel Interfaces Manual						    XBD(4)

NAME

     xbd -- Xen frontend paravirtualized block device interface

SYNOPSIS

     xbd* at xenbus?

DESCRIPTION

     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 cre-
     ation 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.

DIAGNOSTICS

     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.

SEE ALSO

     xbdback(4), xenbus(4), dkctl(8)

HISTORY

     The xbd driver first appeared in NetBSD 3.0.

AUTHORS

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

BSD
								  January 8, 2011							       BSD

XBDBACK(4)						 BSD/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 drivers 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
     identifier.  This identifier is usually associated to the device node as seen by the guest using major(3) and minor(3) numbers.  For example,
     identifier ``769'' (0x301) means major 3 and minor 1, identified as ``hda1'' under Linux convention.  For NetBSD, the guest device name spec-
     ified in the guest configuration file does not matter, and can be chosen arbitrarily.

     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 pro-
     tocol 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>.

BSD
								   June 7, 2011 							       BSD