ui/console: Pass placeholder surface to displays

ui/console used to accept NULL as graphic console surface, but its
semantics was inconsistent among displays:
- cocoa and gtk-egl perform NULL dereference.
- egl-headless, spice and spice-egl do nothing.
- gtk releases underlying resources.
- sdl2-2d and sdl2-gl destroys the window.
- vnc shows a message, "Display output is not active."

Fortunately, only virtio-gpu and virtio-gpu-3d assign NULL so
we can study them to figure out the desired behavior. They assign
NULL *except* for the primary display when the device is realized,
reset, or its scanout is disabled. This effectively destroys
windows for the (uninitialized) secondary displays.

To implement the consistent behavior of display device
realization/reset, this change embeds it to the operation
switching the surface. When NULL was given as a new surface when
switching, ui/console will instead passes a placeholder down
to each display listeners.

sdl destroys the window for a secondary console if its surface is a
placeholder. The other displays simply shows the placeholder.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <20210225101316.83940-2-akihiko.odaki@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/ui/console.c b/ui/console.c
index 32823faf4147dea98a4a9ad98164ebc120b1c6b9..171a7bf14b94fc0d5185fdc68238f8e5e8cf7815 100644 (file)
--- a/ui/console.c
+++ b/ui/console.c
@@ -1675,11 +1675,26 @@ void dpy_gfx_update_full(QemuConsole *con)
 void dpy_gfx_replace_surface(QemuConsole *con,
                              DisplaySurface *surface)
 {
+    static const char placeholder_msg[] = "Display output is not active.";
     DisplayState *s = con->ds;
     DisplaySurface *old_surface = con->surface;
     DisplayChangeListener *dcl;
+    int width;
+    int height;
+
+    if (!surface) {
+        if (old_surface) {
+            width = surface_width(old_surface);
+            height = surface_height(old_surface);
+        } else {
+            width = 640;
+            height = 480;
+        }
+
+        surface = qemu_create_placeholder_surface(width, height, placeholder_msg);
+    }
 
-    assert(old_surface != surface || surface == NULL);
+    assert(old_surface != surface);
 
     con->surface = surface;
     QLIST_FOREACH(dcl, &s->listeners, next) {

diff --git a/ui/gtk.c b/ui/gtk.c
index c32ee34edcaf442a2f715bb81e2c302d36927abc..3edaf041defcf9ea1e4de2dcc76f7d3817375f2a 100644 (file)
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -567,10 +567,6 @@ static void gd_switch(DisplayChangeListener *dcl,
     }
     vc->gfx.ds = surface;
 
-    if (!surface) {
-        return;
-    }
-
     if (surface->format == PIXMAN_x8r8g8b8) {
         /*
          * PIXMAN_x8r8g8b8 == CAIRO_FORMAT_RGB24

diff --git a/ui/sdl2-2d.c b/ui/sdl2-2d.c
index a2ea85127d5729baccf0b2a341f535a8c56bc03c..bfebbdeaea8c304a59a111770a81f7063fe4ac4f 100644 (file)
--- a/ui/sdl2-2d.c
+++ b/ui/sdl2-2d.c
@@ -32,14 +32,11 @@ void sdl2_2d_update(DisplayChangeListener *dcl,
                     int x, int y, int w, int h)
 {
     struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
-    DisplaySurface *surf = qemu_console_surface(dcl->con);
+    DisplaySurface *surf = scon->surface;
     SDL_Rect rect;
     size_t surface_data_offset;
     assert(!scon->opengl);
 
-    if (!surf) {
-        return;
-    }
     if (!scon->texture) {
         return;
     }
@@ -75,7 +72,7 @@ void sdl2_2d_switch(DisplayChangeListener *dcl,
         scon->texture = NULL;
     }
 
-    if (!new_surface) {
+    if (is_placeholder(new_surface) && qemu_console_get_index(dcl->con)) {
         sdl2_window_destroy(scon);
         return;
     }

diff --git a/ui/sdl2-gl.c b/ui/sdl2-gl.c
index fd594d7461109b91e6e3fb07fea2e42fb0c5fd16..a21d2deed91680299c441c017072b2aaba284c49 100644 (file)
--- a/ui/sdl2-gl.c
+++ b/ui/sdl2-gl.c
@@ -86,7 +86,7 @@ void sdl2_gl_switch(DisplayChangeListener *dcl,
 
     scon->surface = new_surface;
 
-    if (!new_surface) {
+    if (is_placeholder(new_surface) && qemu_console_get_index(dcl->con)) {
         qemu_gl_fini_shader(scon->gls);
         scon->gls = NULL;
         sdl2_window_destroy(scon);
@@ -112,7 +112,7 @@ void sdl2_gl_refresh(DisplayChangeListener *dcl)
     assert(scon->opengl);
 
     graphic_hw_update(dcl->con);
-    if (scon->updates && scon->surface) {
+    if (scon->updates && scon->real_window) {
         scon->updates = 0;
         sdl2_gl_render_surface(scon);
     }

diff --git a/ui/spice-display.c b/ui/spice-display.c
index ad93b953a90cc69b0bd5d626bf419c959cdf8c34..d22781a23d06760cb84aefb17ee834ea9341efb7 100644 (file)
--- a/ui/spice-display.c
+++ b/ui/spice-display.c
@@ -388,7 +388,7 @@ void qemu_spice_display_switch(SimpleSpiceDisplay *ssd,
     SimpleSpiceUpdate *update;
     bool need_destroy;
 
-    if (surface && ssd->surface &&
+    if (ssd->surface &&
         surface_width(surface) == pixman_image_get_width(ssd->surface) &&
         surface_height(surface) == pixman_image_get_height(ssd->surface) &&
         surface_format(surface) == pixman_image_get_format(ssd->surface)) {
@@ -410,8 +410,8 @@ void qemu_spice_display_switch(SimpleSpiceDisplay *ssd,
 
     /* full mode switch */
     trace_qemu_spice_display_surface(ssd->qxl.id,
-                                     surface ? surface_width(surface)  : 0,
-                                     surface ? surface_height(surface) : 0,
+                                     surface_width(surface),
+                                     surface_height(surface),
                                      false);
 
     memset(&ssd->dirty, 0, sizeof(ssd->dirty));

diff --git a/ui/vnc.c b/ui/vnc.c
index 4d2151272e5651f83b4aba0ee8a314678bb60742..310abc937812df3a89c2ac06b3a934e32755b5ed 100644 (file)
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -790,20 +790,10 @@ static bool vnc_check_pageflip(DisplaySurface *s1,
 static void vnc_dpy_switch(DisplayChangeListener *dcl,
                            DisplaySurface *surface)
 {
-    static const char placeholder_msg[] =
-        "Display output is not active.";
-    static DisplaySurface *placeholder;
     VncDisplay *vd = container_of(dcl, VncDisplay, dcl);
     bool pageflip = vnc_check_pageflip(vd->ds, surface);
     VncState *vs;
 
-    if (surface == NULL) {
-        if (placeholder == NULL) {
-            placeholder = qemu_create_placeholder_surface(640, 480, placeholder_msg);
-        }
-        surface = placeholder;
-    }
-
     vnc_abort_display_jobs(vd);
     vd->ds = surface;