[RFC PATCH v2 03/11] system/vl: Filter machine list available for a particular target binary

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Binaries can register a QOM type to filter their machines
by filling their TargetInfo::machine_typename field.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/qemu/target_info-impl.h |  3 +++
 include/qemu/target_info.h      |  8 ++++++++
 system/vl.c                     | 14 ++++++++++++++
 target_info.c                   |  5 +++++
 4 files changed, 30 insertions(+)

diff --git a/include/qemu/target_info-impl.h b/include/qemu/target_info-impl.h
index d5c94ed5296..990fb067d20 100644
--- a/include/qemu/target_info-impl.h
+++ b/include/qemu/target_info-impl.h
@@ -16,6 +16,9 @@ typedef struct TargetInfo {
     /* runtime equivalent of TARGET_NAME definition */
     const char *const name;
 
+    /* QOM typename machines for this binary must implement */
+    const char *const machine_typename;
+
 } TargetInfo;
 
 const TargetInfo *target_info(void);
diff --git a/include/qemu/target_info.h b/include/qemu/target_info.h
index 3f6cbbbd300..e9fd2fdd7b0 100644
--- a/include/qemu/target_info.h
+++ b/include/qemu/target_info.h
@@ -16,4 +16,12 @@
  */
 const char *target_name(void);
 
+/**
+ * target_machine_interface_typename:
+ *
+ * Returns: Name of the QOM interface implemented by machines
+ *          usable on this target binary.
+ */
+const char *target_machine_interface_typename(void);
+
 #endif
diff --git a/system/vl.c b/system/vl.c
index d8a0fe713c9..4e43e55afe7 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -27,6 +27,7 @@
 #include "qemu/datadir.h"
 #include "qemu/units.h"
 #include "qemu/module.h"
+#include "qemu/target_info.h"
 #include "exec/cpu-common.h"
 #include "exec/page-vary.h"
 #include "hw/qdev-properties.h"
@@ -836,11 +837,17 @@ static bool usb_parse(const char *cmdline, Error **errp)
 static MachineClass *find_machine(const char *name, GSList *machines)
 {
     GSList *el;
+    const char *qom_typename_filter = target_machine_interface_typename();
 
     for (el = machines; el; el = el->next) {
         MachineClass *mc = el->data;
 
         if (!strcmp(mc->name, name) || !g_strcmp0(mc->alias, name)) {
+            if (qom_typename_filter
+                && !object_class_dynamic_cast(el->data, qom_typename_filter)) {
+                /* Machine is not for this binary: fail */
+                return NULL;
+            }
             return mc;
         }
     }
@@ -1563,6 +1570,7 @@ static void machine_help_func(const QDict *qdict)
     g_autoptr(GSList) machines = NULL;
     GSList *el;
     const char *type = qdict_get_try_str(qdict, "type");
+    const char *qom_typename_filter = target_machine_interface_typename();
 
     machines = object_class_get_list(TYPE_MACHINE, false);
     if (type) {
@@ -1577,6 +1585,12 @@ static void machine_help_func(const QDict *qdict)
     machines = g_slist_sort(machines, machine_class_cmp);
     for (el = machines; el; el = el->next) {
         MachineClass *mc = el->data;
+
+        if (qom_typename_filter
+            && !object_class_dynamic_cast(el->data, qom_typename_filter)) {
+            /* Machine is not for this binary: skip */
+            continue;
+        }
         if (mc->alias) {
             printf("%-20s %s (alias of %s)\n", mc->alias, mc->desc, mc->name);
         }
diff --git a/target_info.c b/target_info.c
index 877a6a15014..226eed1fd7d 100644
--- a/target_info.c
+++ b/target_info.c
@@ -14,3 +14,8 @@ const char *target_name(void)
 {
     return target_info()->name;
 }
+
+const char *target_machine_interface_typename(void)
+{
+    return target_info()->machine_typename;
+}
-- 
2.47.1