diagnostic: warn the user if they are using a software GL renderer

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/backend.h

@@ -240,6 +240,8 @@ struct backend_operations {
 	// ===========         Misc         ============
 	/// Return the driver that is been used by the backend
 	enum driver (*detect_driver)(backend_t *backend_data);
+
+	void (*diagnostics)(backend_t *backend_data);
 };
 
 extern struct backend_operations *backend_list[];

src/backend/gl/glx.c

@@ -26,9 +26,9 @@
 #include "backend/gl/glx.h"
 #include "common.h"
 #include "compiler.h"
-#include "picom.h"
 #include "config.h"
 #include "log.h"
+#include "picom.h"
 #include "region.h"
 #include "utils.h"
 #include "win.h"
@@ -480,6 +480,45 @@ static int glx_buffer_age(backend_t *base) {
 	return (int)val ?: -1;
 }
 
+static void glx_diagnostics(backend_t *base) {
+	struct _glx_data *gd = (void *)base;
+	bool warn_software_rendering = false;
+	const char *software_renderer_names[] = {"llvmpipe", "SWR", "softpipe"};
+	auto glx_vendor = glXGetClientString(gd->display, GLX_VENDOR);
+	printf("* Driver vendors:\n");
+	printf(" * GLX: %s\n", glx_vendor);
+	printf(" * GL: %s\n", glGetString(GL_VENDOR));
+
+	auto gl_renderer = (const char *)glGetString(GL_RENDERER);
+	printf("* GL renderer: %s\n", gl_renderer);
+	if (strcmp(glx_vendor, "Mesa Project and SGI")) {
+		for (size_t i = 0; i < ARR_SIZE(software_renderer_names); i++) {
+			if (strstr(gl_renderer, software_renderer_names[i]) != NULL) {
+				warn_software_rendering = true;
+				break;
+			}
+		}
+	}
+
+#ifdef GLX_MESA_query_renderer
+	if (glxext.has_GLX_MESA_query_renderer) {
+		unsigned int accelerated = 0;
+		glXQueryCurrentRendererIntegerMESA(GLX_RENDERER_ACCELERATED_MESA, &accelerated);
+		printf("* Accelerated: %d\n", accelerated);
+
+		// Trust GLX_MESA_query_renderer when it's available
+		warn_software_rendering = (accelerated == 0);
+	}
+#endif
+
+	if (warn_software_rendering) {
+		printf("\n(You are using a software renderer. Unless you are doing this\n"
+		       "intentionally, this means you don't have a graphics driver\n"
+		       "properly installed. Performance will suffer. Please fix this\n"
+		       "before reporting your issue.)\n");
+	}
+}
+
 struct backend_operations glx_ops = {
     .init = glx_init,
     .deinit = glx_deinit,
@@ -497,6 +536,7 @@ struct backend_operations glx_ops = {
     .create_blur_context = gl_create_blur_context,
     .destroy_blur_context = gl_destroy_blur_context,
     .get_blur_size = gl_get_blur_size,
+    .diagnostics = glx_diagnostics,
     .max_buffer_age = 5,        // Why?
 };
 
@@ -546,6 +586,10 @@ PFNGLXBINDTEXIMAGEEXTPROC glXBindTexImageEXT;
 PFNGLXRELEASETEXIMAGEEXTPROC glXReleaseTexImageEXT;
 PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB;
 
+#ifdef GLX_MESA_query_renderer
+PFNGLXQUERYCURRENTRENDERERINTEGERMESAPROC glXQueryCurrentRendererIntegerMESA;
+#endif
+
 void glxext_init(Display *dpy, int screen) {
 	if (glxext.initialized) {
 		return;
@@ -560,6 +604,9 @@ void glxext_init(Display *dpy, int screen) {
 	check_ext(GLX_EXT_texture_from_pixmap);
 	check_ext(GLX_ARB_create_context);
 	check_ext(GLX_EXT_buffer_age);
+#ifdef GLX_MESA_query_renderer
+	check_ext(GLX_MESA_query_renderer);
+#endif
 #undef check_ext
 
 #define lookup(name) (name = (__typeof__(name))glXGetProcAddress((GLubyte *)#name))
@@ -587,5 +634,10 @@ void glxext_init(Display *dpy, int screen) {
 	if (!lookup(glXCreateContextAttribsARB)) {
 		glxext.has_GLX_ARB_create_context = false;
 	}
+#ifdef GLX_MESA_query_renderer
+	if (!lookup(glXQueryCurrentRendererIntegerMESA)) {
+		glxext.has_GLX_MESA_query_renderer = false;
+	}
+#endif
 #undef lookup
 }

src/backend/gl/glx.h

@@ -54,6 +54,7 @@ struct glxext_info {
 	bool has_GLX_EXT_texture_from_pixmap;
 	bool has_GLX_ARB_create_context;
 	bool has_GLX_EXT_buffer_age;
+	bool has_GLX_MESA_query_renderer;
 };
 
 extern struct glxext_info glxext;
@@ -69,4 +70,8 @@ extern PFNGLXBINDTEXIMAGEEXTPROC glXBindTexImageEXT;
 extern PFNGLXRELEASETEXIMAGEEXTPROC glXReleaseTexImageEXT;
 extern PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB;
 
+#ifdef GLX_MESA_query_renderer
+extern PFNGLXQUERYCURRENTRENDERERINTEGERMESAPROC glXQueryCurrentRendererIntegerMESA;
+#endif
+
 void glxext_init(Display *, int screen);

src/diagnostic.c

@@ -22,9 +22,9 @@ void print_diagnostics(session_t *ps, const char *config_file, bool compositor_r
 	printf("* Use Overlay: %s\n", ps->overlay != XCB_NONE ? "Yes" : "No");
 	if (ps->overlay == XCB_NONE) {
 		if (compositor_running) {
-			printf(" (Another compositor is already running)\n");
+			printf("  (Another compositor is already running)\n");
 		} else if (session_redirection_mode(ps) != XCB_COMPOSITE_REDIRECT_MANUAL) {
-			printf(" (Not in manual redirection mode)\n");
+			printf("  (Not in manual redirection mode)\n");
 		} else {
 			printf("\n");
 		}
@@ -35,6 +35,19 @@ void print_diagnostics(session_t *ps, const char *config_file, bool compositor_r
 	printf("* Config file used: %s\n", config_file ?: "None");
 	printf("\n### Drivers (inaccurate):\n\n");
 	print_drivers(ps->drivers);
+
+	for (int i = 0; i < NUM_BKEND; i++) {
+		if (backend_list[i] && backend_list[i]->diagnostics) {
+			printf("\n### Backend: %s\n\n", BACKEND_STRS[i]);
+			auto data = backend_list[i]->init(ps);
+			if (!data) {
+				printf(" Cannot initialize this backend\n");
+			} else {
+				backend_list[i]->diagnostics(data);
+				backend_list[i]->deinit(data);
+			}
+		}
+	}
 }
 
 // vim: set noet sw=8 ts=8 :