console: add ui module loading support

If a requested user interface is not available, try loading it as
module, simliar to block layer modules.  Needed to keep things working
when followup patches start to build user interfaces as modules.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20180301100547.18962-8-kraxel@redhat.com

Makefile.objs

@@ -56,6 +56,7 @@ common-obj-y += hw/
 common-obj-y += replay/
 
 common-obj-y += ui/
+common-obj-m += ui/
 common-obj-y += bt-host.o bt-vhci.o
 bt-host.o-cflags := $(BLUEZ_CFLAGS)
 

include/qemu/module.h

@@ -53,6 +53,7 @@ typedef enum {
 #define trace_init(function) module_init(function, MODULE_INIT_TRACE)
 
 #define block_module_load_one(lib) module_load_one("block-", lib)
+#define ui_module_load_one(lib) module_load_one("ui-", lib)
 
 void register_module_init(void (*fn)(void), module_init_type type);
 void register_dso_module_init(void (*fn)(void), module_init_type type);

ui/console.c

@@ -2198,6 +2198,9 @@ bool qemu_display_find_default(DisplayOptions *opts)
     int i;
 
     for (i = 0; i < ARRAY_SIZE(prio); i++) {
+        if (dpys[prio[i]] == NULL) {
+            ui_module_load_one(DisplayType_lookup.array[prio[i]]);
+        }
         if (dpys[prio[i]] == NULL) {
             continue;
         }
@@ -2213,6 +2216,9 @@ void qemu_display_early_init(DisplayOptions *opts)
     if (opts->type == DISPLAY_TYPE_NONE) {
         return;
     }
+    if (dpys[opts->type] == NULL) {
+        ui_module_load_one(DisplayType_lookup.array[opts->type]);
+    }
     if (dpys[opts->type] == NULL) {
         error_report("Display '%s' is not available.",
                      DisplayType_lookup.array[opts->type]);