From fab1d32c34213991cae93fdbcbb5338e225f8323 Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Thu, 31 Mar 2016 14:56:36 +0200 Subject: [PATCH] blkif: document how FreeBSD uses the physical-device backend node MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit FreeBSD blkback uses the physical-device-path xenstore node in order to fetch the path to the underlying backing storage (either a block device or raw image). This node is set by the hotplug scripts. Also clarify the usage of the physical-device node. Signed-off-by: Roger Pau Monné Reviewed-by: George Dunlap Acked-by: Ian Jackson --- xen/include/public/io/blkif.h | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h index 99f0326a47..ce0dbfeb19 100644 --- a/xen/include/public/io/blkif.h +++ b/xen/include/public/io/blkif.h @@ -89,15 +89,23 @@ * Values: string * * A free formatted string providing sufficient information for the - * backend driver to open the backing device. (e.g. the path to the - * file or block device representing the backing store.) + * hotplug script to attach the device and provide a suitable + * handler (ie: a block device) for blkback to use. * * physical-device * Values: "MAJOR:MINOR" + * Notes: 11 * * MAJOR and MINOR are the major number and minor number of the * backing device respectively. * + * physical-device-path + * Values: path string + * + * A string that contains the absolute path to the disk image. On + * NetBSD and Linux this is always a block device, while on FreeBSD + * it can be either a block device or a regular file. + * * type * Values: "file", "phy", "tap" * @@ -391,6 +399,7 @@ * than RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST. *(10) The discard-secure property may be present and will be set to 1 if the * backing device supports secure discard. + *(11) Only used by Linux and NetBSD. */ /* -- 2.39.5