[PATCH v2 2/2] tools/ocaml/libs/xc: backward compatible domid control at domain creation time

["Edwin Török" <edvin.torok@citrix.com>]

One can specify the domid to use when creating the domain, but this was hardcoded to 0.

Keep the existing `domain_create` function, and make domid an optional argument.
When not specified default to 0.

A new version of xenopsd can choose to start using this, while old versions of xenopsd will keep
building and using the old API.
(The ABI will change, but that changes every time a function is introduced/removed or modified)

Controlling the domid can be useful during testing or migration.

Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
---
Changed since V1:
* introduced an optional ?domid for better backwards compatibility
* use CAMLparam3 because we have an additional parameter
---
 tools/ocaml/libs/xc/xenctrl.ml      | 5 ++++-
 tools/ocaml/libs/xc/xenctrl.mli     | 4 ++--
 tools/ocaml/libs/xc/xenctrl_stubs.c | 6 +++---
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index e878699b0a..e0a47c4769 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -179,9 +179,12 @@ let with_intf f =
 		handle := Some h;
 		f h
 
-external domain_create: handle -> domctl_create_config -> domid
+external domain_create_stub: handle -> domid -> domctl_create_config -> domid
        = "stub_xc_domain_create"
 
+let domain_create handle ?(domid=0) config =
+	domain_create_stub handle domid config
+
 external domain_sethandle: handle -> domid -> string -> unit
        = "stub_xc_domain_sethandle"
 
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index e64907df8e..84311fa33d 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -143,8 +143,8 @@ val get_handle: unit -> handle option
  * would invalidate the handle that with_intf passes to its argument. *)
 val close_handle: unit -> unit
 
-external domain_create : handle -> domctl_create_config -> domid
-  = "stub_xc_domain_create"
+val domain_create: handle -> ?domid:int -> domctl_create_config -> domid
+
 external domain_sethandle : handle -> domid -> string -> unit = "stub_xc_domain_sethandle"
 external domain_max_vcpus : handle -> domid -> int -> unit
   = "stub_xc_domain_max_vcpus"
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 94aba38a42..9a8dbe5579 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -175,9 +175,9 @@ static unsigned int ocaml_list_to_c_bitmap(value l)
 	return val;
 }
 
-CAMLprim value stub_xc_domain_create(value xch, value config)
+CAMLprim value stub_xc_domain_create(value xch, value wanted_domid, value config)
 {
-	CAMLparam2(xch, config);
+	CAMLparam3(xch, wanted_domid, config);
 	CAMLlocal2(l, arch_domconfig);
 
 	/* Mnemonics for the named fields inside domctl_create_config */
@@ -191,7 +191,7 @@ CAMLprim value stub_xc_domain_create(value xch, value config)
 #define VAL_MAX_MAPTRACK_FRAMES Field(config, 7)
 #define VAL_ARCH                Field(config, 8)
 
-	uint32_t domid = 0;
+	uint32_t domid = Int_val(wanted_domid);
 	int result;
 	struct xen_domctl_createdomain cfg = {
 		.ssidref = Int32_val(VAL_SSIDREF),
-- 
2.29.2