xenbus(4) [netbsd man page]

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

NAME

     xenbus -- Xen bus abstraction for paravirtualized drivers

SYNOPSIS

     xenbus* at hypervisor?

DESCRIPTION

     The xenbus interface offers an abstraction layer used for communications between domains.	xenbus is mainly used by split paravirtualized
     drivers, so backend and frontend devices can exchange configuration information, properties, and statistics.

     xenbus is not used for data transfer (network frames, blocks, PCI commands, ...). This functionality is implemented by each paravirtualized
     driver independently, typically via shared memory pages and an event channel that serves as a virtual interrupt, for signaling.

     The xenbus abstraction offers guests the possibility to read and write information directly from and to XenStore, a centralized database
     accessible to all domains.  For this reason, it also has an event channel associated to it, so that domains can post messages to the XenStore
     facility.

DIAGNOSTICS

     xenbus0: using event channel %d  The event channel associated to the xenbus interface, for communication with the XenStore database.

SEE ALSO

     pciback(4), xbd(4), xbdback(4), xennet(4), xpci(4), xvif(4)

HISTORY

     The xenbus driver first appeared in NetBSD 3.0.

AUTHORS

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

BSD
								  January 8, 2011							       BSD

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