xenbus #18 xenvif #17 xennet #14 xenvbd #16

XENBUS
Handle SDV scan and refine
Re-order refine because it vapourizes the SDV summary log
Refinements to build.py
Uncomment actual build!
Add missing file
Add SDV to normal driver build
Re-worked GNTTAB

XENVIF
Re-order refine because it vapourizes the SDV summary log
Remove IP helper linkage (and hence dependency on netio.sys)
Add SDV to normal driver build
Handle SDV scan and refine
Introduce granter abstraction
Allocate grant references as needed rather than up-front.
Add missing argument to GranterGetReference().
Switch to new GNTTAB interface.

XENNET
Handle SDV scan and refine
Build/SDV refinements

XENVBD
[SCTX-1718] Set DisableCDDB and DontStartRawDevices to 0 before rebooting,
Dont attempt to read values before setting to 0
Fix a few build warnings
Switch to new GNTTAB interface.
Rename XENVBD_CONTEXT to XENVBD_MAPPING to better describe its use
Update blkif.h to include INDIRECT definitions
Track BLKIF_OP_{READ/WRITE} on per request basis, not per SRB
Read additional features/parameters (at appropriate state)
Track Lookaside list max allocs and failed allocs better
Split XENVBD_SEGMENT into segment data and bounce buffer context data
Split PrepareReadWrite into seperate calls for Segments and Requests
Add XENVBD_REQUEST_INDIRECT
Add missing Verbose parameter
Insert INDIRECT operations onto ring
Prepare, submit and cleanup BLKIF_OP_INDIRECT
Tidy up some Verbose and DEBUG output
Pass a tag to blkif_request_t.id instead of a raw pointer.
Zero ring slot after processing response
Enable single requests to be submitted to the ring
Remove unneeded include
Tidy up code with Granter/Notifier/BlockRing accessors
No need to lock when accessing private front ring.
Reduce calls to BlockRingPush and NotifierSend during PdoSubmitPrepared
Tidy up REQUEST preparation code,
Split XENVBD_REQUEST into unioned parts by BLKIF_OP_*
Refactor to improve code clarity
Add handler for SCSIOP_UNMAP, translating to BLKIF_OP_DISCARD
Wrap lookaside list access to an inline structure
Manage SrbStatus better.

Signed-off-by: Ben Chalmers <Ben.Chalmers@citrix.com>