log: Add some diagnostics to the log

Just a few useful things to get this started: egl vendor and extensions,
gles2 extensions, drm and kms info and just a bit of x11 backend info.

src/compositor-drm.c

@@ -1018,6 +1018,8 @@ init_egl(struct drm_compositor *ec, struct udev_device *device)
 		return -1;
 	}
 
+	weston_log("using %s\n", filename);
+
 	ec->drm.fd = fd;
 	ec->gbm = gbm_create_device(ec->drm.fd);
 	ec->base.display = eglGetDisplay(ec->gbm);
@@ -1350,6 +1352,12 @@ create_output_for_connector(struct drm_compositor *ec,
 	output->base.set_dpms = drm_set_dpms;
 	output->base.switch_mode = drm_output_switch_mode;
 
+	weston_log("kms connector %d, crtc %d at mode %dx%d@%.1f\n",
+		   output->connector_id, output->crtc_id,
+		   output->base.current->width,
+		   output->base.current->height,
+		   output->base.current->refresh / 1000.0);
+
 	return 0;
 
 err_surface:
@@ -1748,6 +1756,8 @@ drm_compositor_create(struct wl_display *display,
 	struct wl_event_loop *loop;
 	uint32_t key;
 
+	weston_log("initializing drm backend\n");
+
 	ec = malloc(sizeof *ec);
 	if (ec == NULL)
 		return NULL;

src/compositor-x11.c

@@ -523,6 +523,9 @@ x11_compositor_create_output(struct x11_compositor *c, int x, int y,
 
 	wl_list_insert(c->base.output_list.prev, &output->base.link);
 
+	weston_log("x11 output %dx%d, window id %d\n",
+		   width, height, output->window);
+
 	return 0;
 }
 
@@ -865,6 +868,8 @@ x11_compositor_create(struct wl_display *display,
 	xcb_screen_iterator_t s;
 	int i, x;
 
+	weston_log("initializing x11 backend\n");
+
 	c = malloc(sizeof *c);
 	if (c == NULL)
 		return NULL;

src/compositor.c

@@ -46,6 +46,7 @@
 #include <setjmp.h>
 #include <sys/time.h>
 #include <time.h>
+#include <ctype.h>
 
 #include <wayland-server.h>
 #include "compositor.h"
@@ -2873,6 +2874,26 @@ compositor_bind(struct wl_client *client,
 			     &compositor_interface, id, compositor);
 }
 
+static void
+log_extensions(const char *name, const char *extensions)
+{
+	const char *p, *end;
+	int l;
+
+	l = weston_log("%s:", name);
+	p = extensions;
+	while (*p) {
+		end = strchrnul(p, ' ');
+		if (l + (end - p) > 78)
+			l = weston_log_continue("\n  %.*s", end - p, p);
+		else
+			l += weston_log_continue(" %.*s", end - p, p);
+		for (p = end; isspace(*p); p++)
+			;
+	}
+	weston_log_continue("\n");
+}
+
 WL_EXPORT int
 weston_compositor_init(struct weston_compositor *ec,
 		       struct wl_display *display,
@@ -2913,6 +2934,11 @@ weston_compositor_init(struct weston_compositor *ec,
 
 	wl_display_init_shm(display);
 
+	weston_log("egl vendor: %s\n",
+		   eglQueryString(ec->display, EGL_VENDOR));
+	log_extensions("egl extensions",
+		       eglQueryString(ec->display, EGL_EXTENSIONS));
+
 	ec->image_target_texture_2d =
 		(void *) eglGetProcAddress("glEGLImageTargetTexture2DOES");
 	ec->image_target_renderbuffer_storage = (void *)
@@ -2930,6 +2956,8 @@ weston_compositor_init(struct weston_compositor *ec,
 		return -1;
 	}
 
+	log_extensions("gles2 extensions", extensions);
+
 	if (!strstr(extensions, "GL_EXT_texture_format_BGRA8888")) {
 		weston_log("GL_EXT_texture_format_BGRA8888 not available\n");
 		return -1;