Update to new Xen core platform stack

Update vchan-xen to the interface changes in the new Xen core
platform stack.

Part of mirage/mirage#1159, depends on mirage/mirage-xen#23.

vchan-xen.opam

@@ -18,7 +18,7 @@ depends: [
   "io-page"
   "mirage-flow" {>= "2.0.0"}
   "xenstore" {>= "1.2.2"}
-  "mirage-xen" {>= "5.0.0"}
+  "mirage-xen" {>= "6.0.0"}
   "xenstore_transport" {>= "1.0.0"}
   "sexplib"
   "cmdliner"

xen/dune

@@ -1,6 +1,6 @@
 (library
  (name vchan_xen)
  (public_name vchan-xen)
- (libraries lwt xen-evtchn xenstore xenstore.client mirage-xen mirage-flow vchan)
+ (libraries lwt xenstore xenstore.client mirage-xen mirage-flow vchan)
  (wrapped false)
  (preprocess (pps ppx_sexp_conv)))

xen/events_xen.ml

@@ -26,8 +26,8 @@ let port_of_string x =
 
 let string_of_port = string_of_int
 
-type channel = Eventchn.t
-let sexp_of_channel x = Sexplib.Sexp.Atom (string_of_int (Eventchn.to_int x))
+type channel = OS.Eventchn.t
+let sexp_of_channel x = Sexplib.Sexp.Atom (string_of_int (OS.Eventchn.to_int x))
 
 type event = OS.Activations.event
 let sexp_of_event _ = Sexplib.Sexp.Atom "<event>"
@@ -37,21 +37,21 @@ let initial = OS.Activations.program_start
 let recv = OS.Activations.after
 
 let send channel =
-  let h = Eventchn.init () in
-  Eventchn.notify h channel
+  let h = OS.Eventchn.init () in
+  OS.Eventchn.notify h channel
 
 let listen domid =
-  let h = Eventchn.init () in
-  let port = Eventchn.bind_unbound_port h domid in
-  Eventchn.unmask h port;
-  Eventchn.to_int port, port
+  let h = OS.Eventchn.init () in
+  let port = OS.Eventchn.bind_unbound_port h domid in
+  OS.Eventchn.unmask h port;
+  OS.Eventchn.to_int port, port
 
 let connect domid port =
-  let h = Eventchn.init () in
-  let port' = Eventchn.bind_interdomain h domid port in
-  Eventchn.unmask h port';
+  let h = OS.Eventchn.init () in
+  let port' = OS.Eventchn.bind_interdomain h domid port in
+  OS.Eventchn.unmask h port';
   port'
 
 let close channel =
-  let h = Eventchn.init () in
-  Eventchn.unbind h channel
+  let h = OS.Eventchn.init () in
+  OS.Eventchn.unbind h channel