debian/changelog

+xorg-server (2:1.20.1-5) unstable; urgency=medium
+
+  [ Timo Aaltonen ]
+  * 08_dont-init-glamor-on-llvmpipe.diff: Glamor shouldn't be used on
+    llvmpipe, as it might end up crashing the server on a racy bootup.
+    (LP: #1792932) (Closes: #907655, #910135)
+
+ -- Andreas Boll <aboll@debian.org>  Wed, 10 Oct 2018 18:23:15 +0200
+
 xorg-server (2:1.20.1-4) unstable; urgency=medium
 
   [ Julien Cristau ]

debian/patches/08_dont-init-glamor-on-llvmpipe.diff

+commit 0a9415cf793babed1f28c61f8047d51de04f1528
+Author: Adam Jackson <ajax@redhat.com>
+Date:   Fri Sep 14 11:33:43 2018 -0400
+
+    glamor_egl: Don't initialize on llvmpipe
+    
+    Mesa started supporting GL_OES_EGL_image on llvmpipe in 17.3, after this
+    commit:
+    
+        commit bbdeddd5fd0b797e1e281f058338b3da4d98029d
+        Author: Gurchetan Singh <gurchetansingh@chromium.org>
+        Date:   Tue Aug 1 14:49:33 2017 -0700
+    
+            st/dri: add drisw image extension
+    
+    That's pretty cool, but it means glamor now thinks it can initialize on
+    llvmpipe. This is almost certainly not what anyone wants, as glamor on
+    llvmpipe is pretty much uniformly slower than fb.
+    
+    This fixes both Xorg and Xwayland to refuse glamor in such a setup.
+    Xephyr is left alone, both because glamor is not the default there and
+    because Xephyr+glamor+llvmpipe is one of the easier ways to get xts to
+    exercise glamor.
+    
+    The (very small) downside of this change is that you lose DRI3 support.
+    This wouldn't have helped you very much (since an lp glamor blit is
+    slower than a pixman blit), but it would eliminate the PutImage overhead
+    for llvmpipe's glXSwapBuffers. A future change should add DRI3 support
+    for the fb-only case.
+    
+    Reviewed-by: Eric Anholt <eric@anholt.net>
+    Signed-off-by: Adam Jackson <ajax@redhat.com>
+
+diff --git a/glamor/glamor_egl.c b/glamor/glamor_egl.c
+index df278b1a1..9b930d603 100644
+--- a/glamor/glamor_egl.c
++++ b/glamor/glamor_egl.c
+@@ -898,6 +898,7 @@ Bool
+ glamor_egl_init(ScrnInfoPtr scrn, int fd)
+ {
+     struct glamor_egl_screen_private *glamor_egl;
++    const GLubyte *renderer;
+ 
+     glamor_egl = calloc(sizeof(*glamor_egl), 1);
+     if (glamor_egl == NULL)
+@@ -992,6 +993,14 @@ glamor_egl_init(ScrnInfoPtr scrn, int fd)
+                    "Failed to make EGL context current\n");
+         goto error;
+     }
++
++    renderer = glGetString(GL_RENDERER);
++    if (strstr((const char *)renderer, "llvmpipe")) {
++        xf86DrvMsg(scrn->scrnIndex, X_INFO,
++                   "Refusing to try glamor on llvmpipe\n");
++        goto error;
++    }
++
+     /*
+      * Force the next glamor_make_current call to set the right context
+      * (in case of multiple GPUs using glamor)
+@@ -1005,7 +1014,7 @@ glamor_egl_init(ScrnInfoPtr scrn, int fd)
+     }
+ 
+     xf86DrvMsg(scrn->scrnIndex, X_INFO, "glamor X acceleration enabled on %s\n",
+-               glGetString(GL_RENDERER));
++               renderer);
+ 
+ #ifdef GBM_BO_WITH_MODIFIERS
+     if (epoxy_has_egl_extension(glamor_egl->display,
+diff --git a/hw/xwayland/xwayland-glamor-gbm.c b/hw/xwayland/xwayland-glamor-gbm.c
+index 06fcf5239..25a354bf7 100644
+--- a/hw/xwayland/xwayland-glamor-gbm.c
++++ b/hw/xwayland/xwayland-glamor-gbm.c
+@@ -843,6 +843,11 @@ xwl_glamor_gbm_init_egl(struct xwl_screen *xwl_screen)
+         goto error;
+     }
+ 
++    if (strstr((const char *)glGetString(GL_RENDERER), "llvmpipe")) {
++        ErrorF("Refusing to try glamor on llvmpipe\n");
++        goto error;
++    }
++
+     if (!epoxy_has_gl_extension("GL_OES_EGL_image")) {
+         ErrorF("GL_OES_EGL_image not available\n");
+         goto error;

debian/patches/series

@@ -6,3 +6,4 @@
 05_Revert-Unload-submodules.diff
 06_use-intel-only-on-pre-gen4.diff
 07_use-modesetting-driver-by-default-on-GeForce.diff
+08_dont-init-glamor-on-llvmpipe.diff