Description: xwayland: Detect gbm_bo_get_fd_for_plane at runtime
 `gbm_bo_get_fd_for_plane` was introduced in Mesa 21 but some
 proprietary GBM implementations (Xilinx) still haven't been updated
 to support it:
 ```
 /usr/bin/Xwayland: symbol lookup error: /usr/bin/Xwayland: undefined symbol: gbm_bo_get_fd_for_plane
 ```
 .
 Since distros would like to build a single Xwayland binary for all
 OEMs of the same architecture, we now make the function always
 available.
 .
 If a real implementation of `gbm_bo_get_fd_for_plane` exists at runtime
 then it will be used, otherwise fall back to `gbm_bo_get_fd` or fail.
Author: Daniel van Vugt <daniel.van.vugt@canonical.com>
Origin: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/946
Bug-Ubuntu: https://launchpad.net/bugs/1987628
Forwarded: yes
Last-Update: 2022-08-25

--- a/hw/xwayland/xwayland-glamor-gbm.c
+++ b/hw/xwayland/xwayland-glamor-gbm.c
@@ -32,6 +32,7 @@
 
 #include <fcntl.h>
 #include <errno.h>
+#include <dlfcn.h>
 #include <sys/stat.h>
 #include <xf86drm.h>
 #include <drm_fourcc.h>
@@ -147,6 +148,33 @@ is_device_path_render_node (const char *
     return is_render_node;
 }
 
+static int (*real_gbm_bo_get_fd_for_plane)(struct gbm_bo *, int);
+
+static void
+init_gbm_abi(void)
+{
+    if (!real_gbm_bo_get_fd_for_plane) {
+        real_gbm_bo_get_fd_for_plane = dlsym(RTLD_NEXT,
+                                             "gbm_bo_get_fd_for_plane");
+        if (!real_gbm_bo_get_fd_for_plane)
+            LogMessageVerb(X_WARNING, 0,
+                "gbm_bo_get_fd_for_plane is not supported natively.\n");
+    }
+}
+
+static int
+xwl_gbm_bo_get_fd_for_plane(struct gbm_bo *bo, int plane)
+{
+    if (real_gbm_bo_get_fd_for_plane)
+        return real_gbm_bo_get_fd_for_plane(bo, plane);
+
+    if (plane == 0)
+        return gbm_bo_get_fd(bo);
+
+    errno = ENOSYS;
+    return -1;
+}
+
 static PixmapPtr
 xwl_glamor_gbm_create_pixmap_for_bo(ScreenPtr screen, struct gbm_bo *bo,
                                     int depth,
@@ -155,7 +183,6 @@ xwl_glamor_gbm_create_pixmap_for_bo(Scre
     PixmapPtr pixmap;
     struct xwl_pixmap *xwl_pixmap;
     struct xwl_screen *xwl_screen = xwl_screen_get(screen);
-#ifdef GBM_BO_FD_FOR_PLANE
     struct xwl_gbm_private *xwl_gbm = xwl_gbm_get(xwl_screen);
     uint64_t modifier = gbm_bo_get_modifier(bo);
     const int num_planes = gbm_bo_get_plane_count(bo);
@@ -203,7 +230,6 @@ xwl_glamor_gbm_create_pixmap_for_bo(Scre
     };
 
     for (plane = 0; plane < num_planes; plane++) fds[plane] = -1;
-#endif
 
     xwl_pixmap = calloc(1, sizeof(*xwl_pixmap));
     if (xwl_pixmap == NULL)
@@ -224,7 +250,6 @@ xwl_glamor_gbm_create_pixmap_for_bo(Scre
     xwl_pixmap->buffer = NULL;
     xwl_pixmap->implicit_modifier = implicit_modifier;
 
-#ifdef GBM_BO_FD_FOR_PLANE
     if (xwl_gbm->dmabuf_capable) {
 #define ADD_ATTR(attrs, num, attr)                                      \
         do {                                                            \
@@ -239,7 +264,7 @@ xwl_glamor_gbm_create_pixmap_for_bo(Scre
         ADD_ATTR(img_attrs, attr_num, gbm_bo_get_format(bo));
 
         for (plane = 0; plane < num_planes; plane++) {
-            fds[plane] = gbm_bo_get_fd_for_plane(bo, plane);
+            fds[plane] = xwl_gbm_bo_get_fd_for_plane(bo, plane);
             ADD_ATTR(img_attrs, attr_num, planeAttrs[plane][PLANE_FD]);
             ADD_ATTR(img_attrs, attr_num, fds[plane]);
             ADD_ATTR(img_attrs, attr_num, planeAttrs[plane][PLANE_OFFSET]);
@@ -266,7 +291,6 @@ xwl_glamor_gbm_create_pixmap_for_bo(Scre
         }
     }
     else
-#endif
     {
         xwl_pixmap->image = eglCreateImageKHR(xwl_screen->egl_display,
                                               EGL_NO_CONTEXT,
@@ -1705,6 +1729,8 @@ xwl_glamor_init_gbm(struct xwl_screen *x
         return FALSE;
     }
 
+    init_gbm_abi();
+
     dixSetPrivate(&xwl_screen->screen->devPrivates, &xwl_gbm_private_key,
                   xwl_gbm);
 
--- a/include/meson.build
+++ b/include/meson.build
@@ -109,8 +109,6 @@ conf_data.set('GLAMOR_HAS_GBM_LINEAR',
               build_glamor and gbm_dep.found() and gbm_dep.version().version_compare('>= 10.6') ? '1' : false)
 conf_data.set('GBM_BO_WITH_MODIFIERS',
               build_glamor and gbm_dep.found() and gbm_dep.version().version_compare('>= 17.1') ? '1' : false)
-conf_data.set('GBM_BO_FD_FOR_PLANE',
-              build_glamor and gbm_dep.found() and gbm_dep.version().version_compare('>= 21.1') ? '1' : false)
 conf_data.set('GBM_BO_WITH_MODIFIERS2',
               build_glamor and gbm_dep.found() and gbm_dep.version().version_compare('>= 21.3') ? '1' : false)