8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc #26268

azvegint · 2025-07-11T15:47:33Z

On Linux, we are currently use XRRSetScreenConfigAndRate to change the display mode. This works in most cases, except for some VNC-configured hosts, where the display change may not occur.
One of the conformance tests fails on these hosts.

It was discovered, that the xrandr utility app works fine on these hosts and uses the Crtc and Output Randr APIs, which provide more fine-grained control over display settings.

This changeset utilizes the Crtc and Output Randr APIs to change the display mode.

Currently, changing the display mode is only available when running a single screen.
This limitation remains, but we may remove it in the future. A separate issue has been filed for this purpose.

The awt.x11useOldConfigDisplayMode system property enables the old behavior. Perhaps there's a better name for it.

Testing looks good on VNC and local machines.

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Issue

JDK-8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc (Bug - P2)

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Harshitha Onkar (@honkar-jdk - Reviewer)
Alexander Zuev (@azuev-java - Reviewer)

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bridgekeeper · 2025-07-11T15:48:04Z

👋 Welcome back azvegint! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-07-11T15:49:00Z

@azvegint This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc

Reviewed-by: honkar, kizune

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 27 new commits pushed to the master branch:

0acd065: 8361909: ConstantPoolBuilder::loadableConstantEntry and constantValueEntry should throw NPE
f36147b: 8356942: invokeinterface Throws AbstractMethodError Instead of IncompatibleClassChangeError
5cf672e: 8359053: Implement JEP 504 - Remove the Applet API
... and 24 more: https://git.openjdk.org/jdk/compare/76442f39b9dd583f09a7adebb0fc5f37b6ef88ef...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

openjdk · 2025-07-11T15:49:28Z

@azvegint The following label will be automatically applied to this pull request:

client

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-07-11T15:54:47Z

Webrevs

00: Full (3f1b9473)

mrserb · 2025-07-12T04:08:28Z

except for some VNC-configured hosts
what VNC server is used on that hosts?

azvegint · 2025-07-12T09:39:36Z

except for some VNC-configured hosts

what VNC server is used on that hosts?

It is a TigerVNC with a virtual Xtigervnc server (no physical display is connected).

honkar-jdk

Fix LGTM.
It works as expected on VNC host. No regressions observed with existing java/awt/FullScreen tests on VNC host and on local.

honkar-jdk · 2025-07-15T04:32:36Z

src/java.desktop/unix/native/common/awt/awt_GraphicsEnv.h

@@ -62,4 +62,11 @@ struct X11GraphicsConfigIDs {
    jfieldID bitsPerPixel;
 };

+#define MAX_DISPLAY_MODES 256


File requires copyright year update

It can be handled as a batch copyright year update.

azuev-java · 2025-07-15T04:48:46Z

Seems reasonable. The only strange thing is that passing boolean parameter, immediately negating it and use the new value everywhere. But that's Ok if it increase the code readability which i think it does.

azvegint

/integrate

azvegint · 2025-07-15T06:14:16Z

src/java.desktop/unix/native/common/awt/awt_GraphicsEnv.h

@@ -62,4 +62,11 @@ struct X11GraphicsConfigIDs {
    jfieldID bitsPerPixel;
 };

+#define MAX_DISPLAY_MODES 256


It can be handled as a batch copyright year update.

openjdk · 2025-07-15T06:21:50Z

Going to push as commit 18c2e40.
Since your change was applied there have been 29 commits pushed to the master branch:

40d159d: 8362116: System.in.read() etc. don't accept input once immediate Ctrl+D pressed in JShell
25e509b: 8362097: JFR: Active Settings view broken
0acd065: 8361909: ConstantPoolBuilder::loadableConstantEntry and constantValueEntry should throw NPE
... and 26 more: https://git.openjdk.org/jdk/compare/76442f39b9dd583f09a7adebb0fc5f37b6ef88ef...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-07-15T06:21:58Z

@azvegint Pushed as commit 18c2e40.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

mrserb · 2025-07-15T06:27:36Z

src/java.desktop/unix/classes/sun/awt/X11GraphicsDevice.java

-            xrandrExtSupported =
-                Boolean.valueOf(initXrandrExtension());
+            boolean useOldConfigDisplayMode =
+                    Boolean.getBoolean("awt.x11useOldConfigDisplayMode");


i guess the idea of this property is to share it to the ppl as a workaround in case some errors will occur? Then the CSR might be needed for it. The better name might be: "awt.x11.EnableXrandrDisplayModes"=true.

mrserb · 2025-07-15T06:30:00Z

src/java.desktop/unix/native/libawt_xawt/awt/awt_GraphicsEnv.c

+
+static jint refreshRateFromModeInfo(const XRRModeInfo *modeInfo) {
+    if (!modeInfo->hTotal || !modeInfo->vTotal) {
+        return 0;


It should be REFRESH_RATE_UNKNOWN?

mrserb · 2025-07-15T06:41:43Z

src/java.desktop/unix/native/libawt_xawt/awt/awt_GraphicsEnv.c

+        Bool matchW = (isLandscape ? mode.width : mode.height) == (unsigned int) width;
+        Bool matchH = (isLandscape ? mode.height : mode.width) == (unsigned int) height;
+
+        if (matchW && matchH && rr == refreshRate) {


do we need to stop on the first mode we found or we should select the nearest refrate to the int? or maybe select the largest one? like 59.7 vs 59.9 vs 60?

mrserb · 2025-07-16T17:58:21Z

Additionally to the comments above I think some test should be updated to touch both cases when the new property is set and not.

initial

3f1b947

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8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc #26268

8354415: [Ubuntu25.04] api/java_awt/GraphicsDevice/indexTGF.html#SetDisplayMode - setDisplayMode_REFRESH_RATE_UNKNOWN fails: Height is different on vnc #26268

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