OvmfPkg: Introduce XenBus Protocol.

This protocol will be used for communication between a PV driver (like a
PV block driver) and the XenBus/XenStore.

Change in V5:
- Replace the license by the commonly used file header text.

Change in V3:
- Add disclaimer about the volatile nature of the protocol.
- Add a description on the two introduced members to the protocol.

Change in V2:
- Comment, file header
- Protocol License
- Declare xen interface version earlier
- Rename protocol from Xenbus to XenBus

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16262 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/XenBusDxe/XenBusDxe.h

@@ -18,6 +18,11 @@
 
 #include <Uefi.h>
 
+//
+// Xen interface version used
+//
+#define  __XEN_INTERFACE_VERSION__ 0x00040400
+
 //
 // Libraries
 //
@@ -45,6 +50,7 @@
 //
 // Produced Protocols
 //
+#include <Protocol/XenBus.h>
 
 
 //

OvmfPkg/XenBusDxe/XenBusDxe.inf

@@ -62,6 +62,7 @@
   gEfiPciIoProtocolGuid
   gEfiComponentName2ProtocolGuid
   gEfiComponentNameProtocolGuid
+  gXenBusProtocolGuid
 
 
 [Guids]