ui: Make the DisplayType enum entries conditional

Libvirt's "domcapabilities" command has a way to state whether certain
graphic frontends are available in QEMU or not. Originally, libvirt
looked at the "--help" output of the QEMU binary to determine whether
SDL was available or not (by looking for the "-sdl" parameter in the
help text), but since libvirt stopped doing this analysis of the help
text, the detection of SDL is currently broken, see:

 https://bugzilla.redhat.com/show_bug.cgi?id=1790902

QEMU should provide a way via the QMP interface instead. A simple way,
without introducing additional commands, is to make the DisplayType
enum entries conditional, so that the enum only contains the entries if
the corresponding CONFIG_xxx switches have been set. This of course
only gives an indication which possibilities have been enabled during
compile-time of QEMU (and does not take into account whether modules
are later available or not for example - for this we'd need a separate
command), but anyway, this should already be good enough for the above
bug ticket, and it's a good idea anyway to make the QMP interface
conditional here, so let's simply do it.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210615090439.70926-1-thuth@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/ui/console.c b/ui/console.c
index 2de5f41..1103b65 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -2370,13 +2370,19 @@ void qemu_display_register(QemuDisplay *ui)
 bool qemu_display_find_default(DisplayOptions *opts)
 {
     static DisplayType prio[] = {
+#if defined(CONFIG_GTK)
         DISPLAY_TYPE_GTK,
+#endif
+#if defined(CONFIG_SDL)
         DISPLAY_TYPE_SDL,
+#endif
+#if defined(CONFIG_COCOA)
         DISPLAY_TYPE_COCOA
+#endif
     };
     int i;
 
-    for (i = 0; i < ARRAY_SIZE(prio); i++) {
+    for (i = 0; i < (int)ARRAY_SIZE(prio); i++) {
         if (dpys[prio[i]] == NULL) {
             ui_module_load_one(DisplayType_str(prio[i]));
         }