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
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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