Changeset 74581 in vbox for trunk

Timestamp:

Oct 2, 2018 2:01:09 PM (7 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

125454

Message:

Additions/linux/vboxvideo: better work-around for missing dirty rectangles.
bugref:9235: No screenshot for Linux VM
Background: a long time ago, Linux user-space applications using the DRM
graphics interface did not need to provide the graphics driver with dirty
rectangle information. This was changed to make life easier for virtual
devices like ours, but the version of Plymouth (the splash screen at system
boot) in recent Ubuntu 14.04 versions does not do it. We did some nasty
tricks to make the hardware notice screen updates anyway, and they caused
screenshots in Linux virtual machines not to work (and might have other side
effects).
This changes removes the tricks mentioned above, and instead introduces a
twice-a-second refresh timer in the driver. As this is only intended for that
version of Plymouth, we disable the timer as soon as we either receive dirty
rectangle information, or the user-space client shows that it can handle
screen resizes (which Plymouth cannot, at least that version). Once page flip
support is integrated we could use that as a test instead of the second, but
only if there is actually a need. Twice a second refresh is quite a high
overhead, but it is only incurred in that rare case, and usually only for a
few seconds at that.

Location:

trunk/src/VBox/Additions/linux/drm

Files:

• vbox_drv.c (modified) (2 diffs)
• vbox_drv.h (modified) (2 diffs)
• vbox_main.c (modified) (3 diffs)
• vbox_mode.c (modified) (2 diffs)

trunk/src/VBox/Additions/linux/drm/vbox_drv.c

@@ -227 +227 @@
 
         mutex_lock(&vbox->hw_mutex);
-        /*
-         * Disable VBVA when someone releases master in case the next person
-         * tries tries to do VESA.
-         */
-        /** @todo work out if anyone is likely to and whether it will work. */
-        /*
-         * Update: we also disable it because if the new master does not do
-         * dirty rectangle reporting (e.g. old versions of Plymouth) then at
-         * least the first screen will still be updated. We enable it as soon
-         * as we receive a dirty rectangle report.
-         */
-        vbox_disable_accel(vbox);
+        /* Start the refresh timer in case the user does not provide dirty
+         * rectangles. */
+        vbox->need_refresh_timer = true;
+        schedule_delayed_work(&vbox->refresh_work, VBOX_REFRESH_PERIOD);
         mutex_unlock(&vbox->hw_mutex);
 
@@ -257 +249 @@
 
         mutex_lock(&vbox->hw_mutex);
-        vbox_disable_accel(vbox);
+        vbox->need_refresh_timer = false;
         mutex_unlock(&vbox->hw_mutex);
 }

trunk/src/VBox/Additions/linux/drm/vbox_drv.h

@@ -124 +124 @@
 #define HOST_FLAGS_OFFSET GUEST_HEAP_USABLE_SIZE
 
+/** How frequently we refresh if the guest is not providing dirty rectangles. */
+#define VBOX_REFRESH_PERIOD (HZ / 2)
+
 struct vbox_fbdev;
 
@@ -161 +164 @@
          */
         bool initial_mode_queried;
+        /**
+         * Do we know that the current user can send us dirty rectangle information?
+         * If not, do periodic refreshes until we do know.
+         */
+        bool need_refresh_timer;
+        /**
+         * As long as the user is not sending us dirty rectangle information,
+         * refresh the whole screen at regular intervals.
+         */
+        struct delayed_work refresh_work;
         struct work_struct hotplug_work;
         u32 input_mapping_width;

trunk/src/VBox/Additions/linux/drm/vbox_main.c

@@ -109 +109 @@
         unsigned int i;
 
+        /* The user can send rectangles, we do not need the timer. */
+        vbox->need_refresh_timer = false;
         mutex_lock(&vbox->hw_mutex);
         list_for_each_entry(crtc, &fb->dev->mode_config.crtc_list, head) {
                 if (CRTC_FB(crtc) == fb) {
-                        vbox_enable_accel(vbox);
                         for (i = 0; i < num_rects; ++i) {
                                 VBVACMDHDR cmd_hdr;
@@ -297 +298 @@
 
 /**
+ * Our refresh timer call-back.  Only used for guests without dirty rectangle
+ * support.
+ */
+static void vbox_refresh_timer(struct work_struct *work)
+{
+        struct vbox_private *vbox = container_of(work, struct vbox_private,
+                                                                                                 refresh_work.work);
+        bool have_unblanked = false;
+        struct drm_crtc *crtci;
+
+        if (!vbox->need_refresh_timer)
+                return;
+        list_for_each_entry(crtci, &vbox->dev->mode_config.crtc_list, head) {
+                struct vbox_crtc *vbox_crtc = to_vbox_crtc(crtci);
+                if (crtci->enabled && !vbox_crtc->blanked)
+                        have_unblanked = true;
+        }
+        if (!have_unblanked)
+                return;
+        /* This forces a full refresh. */
+        vbox_enable_accel(vbox);
+        /* Schedule the next timer iteration. */
+        schedule_delayed_work(&vbox->refresh_work, VBOX_REFRESH_PERIOD);
+}
+
+/**
  * Set up our heaps and data exchange buffers in VRAM before handing the rest
  * to the memory manager.
@@ -342 +369 @@
                 return -ENOMEM;
 
-        return vbox_accel_init(vbox);
+        ret = vbox_accel_init(vbox);
+        if (ret)
+                return ret;
+        /* Set up the refresh timer for users which do not send dirty rectangles. */
+        INIT_DELAYED_WORK(&vbox->refresh_work, vbox_refresh_timer);
+        return 0;
 }
 
 static void vbox_hw_fini(struct vbox_private *vbox)
 {
+        vbox->need_refresh_timer = false;
+        cancel_delayed_work(&vbox->refresh_work);
         vbox_accel_fini(vbox);
         kfree(vbox->last_mode_hints);

trunk/src/VBox/Additions/linux/drm/vbox_mode.c

@@ -160 +160 @@
         case DRM_MODE_DPMS_ON:
                 vbox_crtc->blanked = false;
+                /* Restart the refresh timer if necessary. */
+                schedule_delayed_work(&vbox->refresh_work, VBOX_REFRESH_PERIOD);
                 break;
         case DRM_MODE_DPMS_STANDBY:
@@ -568 +570 @@
                 return drm_add_modes_noedid(connector, 800, 600);
         }
+        /* Also assume that a client which supports hot-plugging also knows
+         * how to update the screen in a way we can use, the only known
+         * relevent client which cannot is Plymouth in Ubuntu 14.04. */
+        vbox->need_refresh_timer = false;
         num_modes = drm_add_modes_noedid(connector, 2560, 1600);
         preferred_width = vbox_connector->mode_hint.width ?