Public bug reported: From: https://bugreports.qt.io/browse/QTBUG-66348
** extract ** The `QOpenGLShaderProgram` class in Qt can be used to compile and link OpenGL shaders. If the `GL_ARB_get_program_binary` OpenGL extension is available, it can cache those shaders on disk (~/.cache/qtshadercache). The i965 driver in Mesa supports this extension since version 18.0.0. When the shader is loaded using the `glProgramBinary` function, OpenGL can refuse it if for example some hardware or software component changed. Mesa refuses binaries that were created by any other build of Mesa (using among other things the build_id of the library). If the shader is refused, Qt should fallback to compiling it from sources, but it incorrectly calls glLinkProgram first. The glLinkProgram succeeds, because it actually links 0 shaders together. That is allowed in OpenGL compatibility profile and the resulting program works as a fixed pipeline. Which of course does not render as expected. This causes rendering errors in Qt applications every time Mesa is updated since version 18.0.0. For example white screen in sddm. This issue was originally reported in openSUSE (https://bugzilla.opensuse.org/show_bug.cgi?id=1080578). ** end extract ** As this potentially effects Qt applications, and could even render display manager login unusable, this should be a blocking bug in mesa and Qt until Qt mitigations patches pass codereview and can be included in Qtbase for 18.04. ** Affects: mesa (Ubuntu) Importance: Undecided Status: New ** Affects: qtbase-opensource-src (Ubuntu) Importance: Undecided Status: New ** Affects: mesa (Ubuntu Bionic) Importance: Undecided Status: New ** Affects: qtbase-opensource-src (Ubuntu Bionic) Importance: Undecided Status: New ** Tags: block-proposed ** Also affects: qtbase-opensource-src (Ubuntu) Importance: Undecided Status: New ** Also affects: mesa (Ubuntu Bionic) Importance: Undecided Status: New ** Also affects: qtbase-opensource-src (Ubuntu Bionic) Importance: Undecided Status: New ** Tags added: block-proposed -- You received this bug notification because you are a member of Ubuntu SDK bug tracking, which is subscribed to qtbase-opensource-src in Ubuntu. https://bugs.launchpad.net/bugs/1749472 Title: mesa 18.0.0 will cause rendering errors in Qt applications Status in mesa package in Ubuntu: New Status in qtbase-opensource-src package in Ubuntu: New Status in mesa source package in Bionic: New Status in qtbase-opensource-src source package in Bionic: New Bug description: From: https://bugreports.qt.io/browse/QTBUG-66348 ** extract ** The `QOpenGLShaderProgram` class in Qt can be used to compile and link OpenGL shaders. If the `GL_ARB_get_program_binary` OpenGL extension is available, it can cache those shaders on disk (~/.cache/qtshadercache). The i965 driver in Mesa supports this extension since version 18.0.0. When the shader is loaded using the `glProgramBinary` function, OpenGL can refuse it if for example some hardware or software component changed. Mesa refuses binaries that were created by any other build of Mesa (using among other things the build_id of the library). If the shader is refused, Qt should fallback to compiling it from sources, but it incorrectly calls glLinkProgram first. The glLinkProgram succeeds, because it actually links 0 shaders together. That is allowed in OpenGL compatibility profile and the resulting program works as a fixed pipeline. Which of course does not render as expected. This causes rendering errors in Qt applications every time Mesa is updated since version 18.0.0. For example white screen in sddm. This issue was originally reported in openSUSE (https://bugzilla.opensuse.org/show_bug.cgi?id=1080578). ** end extract ** As this potentially effects Qt applications, and could even render display manager login unusable, this should be a blocking bug in mesa and Qt until Qt mitigations patches pass codereview and can be included in Qtbase for 18.04. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mesa/+bug/1749472/+subscriptions -- Mailing list: https://launchpad.net/~ubuntu-sdk-bugs Post to : ubuntu-sdk-bugs@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-sdk-bugs More help : https://help.launchpad.net/ListHelp
