[Xen-devel] [PATCH v2 1/7] blkif: document how FreeBSD uses the physical-device backend node

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

FreeBSD blkback uses the physical-device 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.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
---
 xen/include/public/io/blkif.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/include/public/io/blkif.h b/xen/include/public/io/blkif.h
index 99f0326..9a5baa4 100644
--- a/xen/include/public/io/blkif.h
+++ b/xen/include/public/io/blkif.h
@@ -89,14 +89,18 @@
  *      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"
+ * physical-device:
+ *      Values:         OS specific
  *
- *      MAJOR and MINOR are the major number and minor number of the
- *      backing device respectively.
+ *      A free formatted string that contains the OS specific path to the
+ *      backing device for this blkback instance.
+ *
+ *      Linux and NetBSD encode the block device major and minor numbers using
+ *      the following printf format: "%x:%x", while FreeBSD places the path to
+ *      the file or device in the filesystem.
  *
  * type
  *      Values:         "file", "phy", "tap"
-- 
2.5.4 (Apple Git-61)


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