Add option to create device nodes

This change adds a --create-device-nodes option to the
nvidia-ctk system create-dev-char-symlinks command to create
device nodes. The currently only creates control device nodes.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk/system/create-dev-char-symlinks/create-dev-char-symlinks.go

@@ -44,6 +44,7 @@ type config struct {
 	dryRun            bool
 	watch             bool
 	createAll         bool
+	createDeviceNodes bool
 	loadKernelModules bool
 }
 
@@ -105,6 +106,12 @@ func (m command) build() *cli.Command {
 			Destination: &cfg.loadKernelModules,
 			EnvVars:     []string{"LOAD_KERNEL_MODULES"},
 		},
+		&cli.BoolFlag{
+			Name:        "create-device-nodes",
+			Usage:       "Create the NVIDIA control device nodes in the driver root if they do not exist. This is only applicable when --create-all is set",
+			Destination: &cfg.createDeviceNodes,
+			EnvVars:     []string{"CREATE_DEVICE_NODES"},
+		},
 		&cli.BoolFlag{
 			Name:        "dry-run",
 			Usage:       "If set, the command will not create any symlinks.",
@@ -127,6 +134,11 @@ func (m command) validateFlags(r *cli.Context, cfg *config) error {
 		cfg.loadKernelModules = false
 	}
 
+	if cfg.createDeviceNodes && !cfg.createAll {
+		m.logger.Warn("create-device-nodes is only applicable when create-all is set; ignoring")
+		cfg.createDeviceNodes = false
+	}
+
 	return nil
 }
 
@@ -151,6 +163,7 @@ func (m command) run(c *cli.Context, cfg *config) error {
 		WithDryRun(cfg.dryRun),
 		WithCreateAll(cfg.createAll),
 		WithLoadKernelModules(cfg.loadKernelModules),
+		WithCreateDeviceNodes(cfg.createDeviceNodes),
 	)
 	if err != nil {
 		return fmt.Errorf("failed to create symlink creator: %v", err)
@@ -206,6 +219,7 @@ type linkCreator struct {
 	devCharPath       string
 	dryRun            bool
 	createAll         bool
+	createDeviceNodes bool
 	loadKernelModules bool
 }
 
@@ -233,18 +247,9 @@ func NewSymlinkCreator(opts ...Option) (Creator, error) {
 		c.devCharPath = defaultDevCharPath
 	}
 
-	if c.loadKernelModules {
+	if err := c.setup(); err != nil {
-		s, err := system.New(
-			system.WithLogger(c.logger),
-			system.WithDryRun(c.dryRun),
-		)
-		if err != nil {
 		return nil, err
 	}
-		if err := s.LoadNVIDIAKernelModules(); err != nil {
-			return nil, fmt.Errorf("failed to load NVIDIA kernel modules: %v", err)
-		}
-	}
 
 	if c.createAll {
 		lister, err := newAllPossible(c.logger, c.driverRoot)
@@ -258,6 +263,34 @@ func NewSymlinkCreator(opts ...Option) (Creator, error) {
 	return c, nil
 }
 
+func (m linkCreator) setup() error {
+	if !m.loadKernelModules && !m.createDeviceNodes {
+		return nil
+	}
+
+	s, err := system.New(
+		system.WithLogger(m.logger),
+		system.WithDryRun(m.dryRun),
+	)
+	if err != nil {
+		return err
+	}
+
+	if m.loadKernelModules {
+		if err := s.LoadNVIDIAKernelModules(); err != nil {
+			return fmt.Errorf("failed to load NVIDIA kernel modules: %v", err)
+		}
+	}
+
+	if m.createDeviceNodes {
+		if err := s.CreateNVIDIAControlDeviceNodesAt(m.driverRoot); err != nil {
+			return fmt.Errorf("failed to create NVIDIA device nodes: %v", err)
+		}
+	}
+
+	return nil
+}
+
 // WithDriverRoot sets the driver root path.
 func WithDriverRoot(root string) Option {
 	return func(c *linkCreator) {
@@ -300,6 +333,13 @@ func WithLoadKernelModules(loadKernelModules bool) Option {
 	}
 }
 
+// WithCreateDeviceNodes sets the createDeviceNodes flag for the linkCreator.
+func WithCreateDeviceNodes(createDeviceNodes bool) Option {
+	return func(lc *linkCreator) {
+		lc.createDeviceNodes = createDeviceNodes
+	}
+}
+
 // CreateLinks creates symlinks for all NVIDIA device nodes found in the driver root.
 func (m linkCreator) CreateLinks() error {
 	deviceNodes, err := m.lister.DeviceNodes()