Re: [PATCH v21 03/18] ui/egl: Don't change bound GL context when creating new context

[Akihiko Odaki]

On 2026/03/03 21:05, Dmitry Osipenko wrote:

On 3/3/26 06:49, Akihiko Odaki wrote:

On 2026/03/02 23:59, Dmitry Osipenko wrote:

Don't change bound GL context when creating new GL context for
consistency
with behavior expected by virglrenderer that assumes context-creation
doesn't
switch context. eglCreateContext() doesn't require GL context to be bound
when it's invoked. Update qemu_egl_create_context() to spawn GL sub-
contexts
from a common parent GL context instead of a currently-bound context.

Signed-off-by: Dmitry Osipenko <dmitry.osipe...@collabora.com>
---
   ui/dbus.c          | 2 --
   ui/egl-context.c   | 3 +--
   ui/egl-headless.c  | 2 --
   ui/gtk-egl.c       | 4 ----
   ui/spice-display.c | 2 --
   5 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/ui/dbus.c b/ui/dbus.c
index 905ee6fea71b..750a064e3fbf 100644
--- a/ui/dbus.c
+++ b/ui/dbus.c
@@ -47,8 +47,6 @@ static DBusDisplay *dbus_display;
   static QEMUGLContext dbus_create_context(DisplayGLCtx *dgc,
                                            QEMUGLParams *params)
   {
-    eglMakeCurrent(qemu_egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
-                   qemu_egl_rn_ctx);
       return qemu_egl_create_context(dgc, params);
   }
   diff --git a/ui/egl-context.c b/ui/egl-context.c
index aed3e3ba1f3f..f9a998768beb 100644
--- a/ui/egl-context.c
+++ b/ui/egl-context.c
@@ -19,8 +19,7 @@ QEMUGLContext qemu_egl_create_context(DisplayGLCtx
*dgc,
      };
      bool gles = (qemu_egl_mode == DISPLAY_GL_MODE_ES);
   -   ctx = eglCreateContext(qemu_egl_display, qemu_egl_config,
-                          eglGetCurrentContext(),
+   ctx = eglCreateContext(qemu_egl_display, qemu_egl_config,
qemu_egl_rn_ctx,
                             gles ? ctx_att_gles : ctx_att_core);
      return ctx;
   }
diff --git a/ui/egl-headless.c b/ui/egl-headless.c
index 1f6b845500dd..19955792ac95 100644
--- a/ui/egl-headless.c
+++ b/ui/egl-headless.c
@@ -42,8 +42,6 @@ static void egl_gfx_switch(DisplayChangeListener *dcl,
   static QEMUGLContext egl_create_context(DisplayGLCtx *dgc,
                                           QEMUGLParams *params)
   {
-    eglMakeCurrent(qemu_egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
-                   qemu_egl_rn_ctx);
       return qemu_egl_create_context(dgc, params);
   }
   diff --git a/ui/gtk-egl.c b/ui/gtk-egl.c
index 0dbb429958e5..6b3519419039 100644
--- a/ui/gtk-egl.c
+++ b/ui/gtk-egl.c
@@ -217,10 +217,6 @@ void gd_egl_switch(DisplayChangeListener *dcl,
   QEMUGLContext gd_egl_create_context(DisplayGLCtx *dgc,
                                       QEMUGLParams *params)
   {
-    VirtualConsole *vc = container_of(dgc, VirtualConsole, gfx.dgc);
-
-    eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
-                   vc->gfx.esurface, vc->gfx.ectx);

This uses vc->gfx.ectx instead of qemu_egl_rn_ctx so it should be passed
to qemu_egl_create_context().

Good catch. AFAICS, the vc->gfx.ectx is initialized only once in the
code. Will double check.

One problem with gtk-egl display is that this is the only display type I
haven't tested because it's not obvious how to do it, The gdk-area is
what always get used on my machine with both x11 and wayland, and
forcing gtk-egl in the code instead of gdk-area results in a crash. I'd
appreciate if anyone could clarify how to make QEMU use gtk-egl or
whether it has been obsoleted and doesn't work with modern GTK.

The following worked for me:
GDK_BACKEND=x11 qemu-system-aarch64 -M virt -display gtk,gl=on

Regards,
Akihiko Odaki