This patch adds a new source module, xen-bus-helper.c, which builds on
basic libxenstore primitives to provide functions to create (setting
permissions appropriately) and destroy xenstore areas, and functions to
'printf' and 'scanf' nodes therein. The main xen-bus code then uses
these primitives [1] to initialize and destroy the frontend and backend
areas for a XenDevice during realize and unrealize respectively.
The 'xen-block' implementation is extended with a 'get_name' method that
returns the VBD number. This number is required to 'name' the xenstore
areas.
NOTE: An exit handler is also added to make sure the xenstore areas are
cleaned up if QEMU terminates without devices being unrealized.
[1] The 'scanf' functions are actually not yet needed, but they will be
needed by code delivered in subsequent patches.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This patch adds new XenDevice-s: 'xen-disk' and 'xen-cdrom', both derived
from a common 'xen-block' parent type. These will eventually replace the
'xen_disk' (note the underscore rather than hyphen) legacy PV backend but
it is illustrative to build up the implementation incrementally, along with
the XenBus/XenDevice framework. Subsequent patches will therefore add to
these devices' implementation as new features are added to the framework.
After this patch has been applied it is possible to instantiate new
'xen-disk' or 'xen-cdrom' devices with a single 'vdev' parameter, which
accepts values adhering to the Xen VBD naming scheme [1]. For example, a
command-line instantiation of a xen-disk can be done with an argument
similar to the following:
-device xen-disk,vdev=hda
The implementation of the vdev parameter formulates the appropriate VBD
number for use in the PV protocol.
[1] https://xenbits.xen.org/docs/unstable/man/xen-vbd-interface.7.html
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>