From ff07eab85b5c6b728ad3cc99d02e9f2ae8b9854f Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Tue, 12 Dec 2023 15:25:10 +0100
Subject: [PATCH] Detect Nvidia proprietary driver via drmGetVersion()

This is less punishing for users with the Nvidia driver loaded but
not used by Sway (e.g. for CUDA).
---
 include/sway/server.h |  2 ++
 meson.build           |  3 +--
 sway/main.c           | 29 +----------------------------
 sway/server.c         | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 36 insertions(+), 30 deletions(-)

diff --git a/include/sway/server.h b/include/sway/server.h
index 1b3166ce..bf195706 100644
--- a/include/sway/server.h
+++ b/include/sway/server.h
@@ -163,6 +163,8 @@ struct sway_debug {
 
 extern struct sway_debug debug;
 
+extern bool allow_unsupported_gpu;
+
 bool server_init(struct sway_server *server);
 void server_fini(struct sway_server *server);
 bool server_start(struct sway_server *server);
diff --git a/meson.build b/meson.build
index adf49c19..e65723b6 100644
--- a/meson.build
+++ b/meson.build
@@ -77,8 +77,7 @@ pixman = dependency('pixman-1')
 libevdev = dependency('libevdev')
 libinput = wlroots_features['libinput_backend'] ? dependency('libinput', version: '>=1.21.0') : null_dep
 xcb = dependency('xcb', required: get_option('xwayland'))
-drm_full = dependency('libdrm') # only needed for drm_fourcc.h
-drm = drm_full.partial_dependency(compile_args: true, includes: true)
+drm = dependency('libdrm')
 libudev = wlroots_features['libinput_backend'] ? dependency('libudev') : null_dep
 math = cc.find_library('m')
 rt = cc.find_library('rt')
diff --git a/sway/main.c b/sway/main.c
index 0db116d3..98aba7f2 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -49,32 +49,6 @@ void sig_handler(int signal) {
 	sway_terminate(EXIT_SUCCESS);
 }
 
-void detect_proprietary(int allow_unsupported_gpu) {
-	FILE *f = fopen("/proc/modules", "r");
-	if (!f) {
-		return;
-	}
-	char *line = NULL;
-	size_t line_size = 0;
-	while (getline(&line, &line_size, f) != -1) {
-		if (strncmp(line, "nvidia ", 7) == 0) {
-			if (allow_unsupported_gpu) {
-				sway_log(SWAY_ERROR,
-						"!!! Proprietary Nvidia drivers are in use !!!");
-			} else {
-				sway_log(SWAY_ERROR,
-					"Proprietary Nvidia drivers are NOT supported. "
-					"Use Nouveau. To launch sway anyway, launch with "
-					"--unsupported-gpu and DO NOT report issues.");
-				exit(EXIT_FAILURE);
-			}
-			break;
-		}
-	}
-	free(line);
-	fclose(f);
-}
-
 void run_as_ipc_client(char *command, char *socket_path) {
 	int socketfd = ipc_open_socket(socket_path);
 	uint32_t len = strlen(command);
@@ -243,7 +217,7 @@ static const char usage[] =
 	"\n";
 
 int main(int argc, char **argv) {
-	static bool verbose = false, debug = false, validate = false, allow_unsupported_gpu = false;
+	static bool verbose = false, debug = false, validate = false;
 
 	char *config_path = NULL;
 
@@ -351,7 +325,6 @@ int main(int argc, char **argv) {
 		return 0;
 	}
 
-	detect_proprietary(allow_unsupported_gpu);
 	increase_nofile_limit();
 
 	// handle SIGTERM signals
diff --git a/sway/server.c b/sway/server.c
index be521621..267e46c0 100644
--- a/sway/server.c
+++ b/sway/server.c
@@ -37,6 +37,7 @@
 #include <wlr/types/wlr_xdg_foreign_v1.h>
 #include <wlr/types/wlr_xdg_foreign_v2.h>
 #include <wlr/types/wlr_xdg_output_v1.h>
+#include <xf86drm.h>
 #include "config.h"
 #include "list.h"
 #include "log.h"
@@ -60,6 +61,8 @@
 #define SWAY_XDG_SHELL_VERSION 2
 #define SWAY_LAYER_SHELL_VERSION 4
 
+bool allow_unsupported_gpu = false;
+
 #if WLR_HAS_DRM_BACKEND
 static void handle_drm_lease_request(struct wl_listener *listener, void *data) {
 	/* We only offer non-desktop outputs, but in the future we might want to do
@@ -113,6 +116,33 @@ static bool filter_global(const struct wl_client *client,
 	return true;
 }
 
+static void detect_proprietary(struct wlr_backend *backend, void *data) {
+	int drm_fd = wlr_backend_get_drm_fd(backend);
+	if (drm_fd < 0) {
+		return;
+	}
+
+	drmVersion *version = drmGetVersion(drm_fd);
+	if (version == NULL) {
+		sway_log(SWAY_ERROR, "drmGetVersion() failed");
+		return;
+	}
+
+	if (strcmp(version->name, "nvidia-drm") == 0) {
+		if (allow_unsupported_gpu) {
+			sway_log(SWAY_ERROR, "!!! Proprietary Nvidia drivers are in use !!!");
+		} else {
+			sway_log(SWAY_ERROR,
+				"Proprietary Nvidia drivers are NOT supported. "
+				"Use Nouveau. To launch sway anyway, launch with "
+				"--unsupported-gpu and DO NOT report issues.");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	drmFreeVersion(version);
+}
+
 bool server_init(struct sway_server *server) {
 	sway_log(SWAY_DEBUG, "Initializing Wayland server");
 	server->wl_display = wl_display_create();
@@ -128,6 +158,8 @@ bool server_init(struct sway_server *server) {
 		return false;
 	}
 
+	wlr_multi_for_each_backend(server->backend, detect_proprietary, NULL);
+
 	server->renderer = wlr_renderer_autocreate(server->backend);
 	if (!server->renderer) {
 		sway_log(SWAY_ERROR, "Failed to create renderer");