Merge branch 'for-5.11-null-console' into for-linus (5f3b8d39) · Commits · 戴 / test

drivers/tty/Kconfig

+0 −14

Original line number	Diff line number	Diff line
		@@ -428,20 +428,6 @@ config MIPS_EJTAG_FDC_KGDB_CHAN
		help
		FDC channel number to use for KGDB.

		config NULL_TTY
		tristate "NULL TTY driver"
		help
		Say Y here if you want a NULL TTY which simply discards messages.

		This is useful to allow userspace applications which expect a console
		device to work without modifications even when no console is
		available or desired.

		In order to use this driver, you should redirect the console to this
		TTY, or boot the kernel with console=ttynull.

		If unsure, say N.

		config TRACE_ROUTER
		tristate "Trace data router for MIPI P1149.7 cJTAG standard"
		depends on TRACE_SINK

+1 −2

Original line number	Diff line number	Diff line
		@@ -2,7 +2,7 @@
		obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \
		tty_buffer.o tty_port.o tty_mutex.o \
		tty_ldsem.o tty_baudrate.o tty_jobctrl.o \
		n_null.o
		n_null.o ttynull.o
		obj-$(CONFIG_LEGACY_PTYS) += pty.o
		obj-$(CONFIG_UNIX98_PTYS) += pty.o
		obj-$(CONFIG_AUDIT) += tty_audit.o
		@@ -25,7 +25,6 @@ obj-$(CONFIG_ISI) += isicom.o
		obj-$(CONFIG_MOXA_INTELLIO) += moxa.o
		obj-$(CONFIG_MOXA_SMARTIO) += mxser.o
		obj-$(CONFIG_NOZOMI) += nozomi.o
		obj-$(CONFIG_NULL_TTY) += ttynull.o
		obj-$(CONFIG_ROCKETPORT) += rocket.o
		obj-$(CONFIG_SYNCLINK_GT) += synclink_gt.o
		obj-$(CONFIG_SYNCLINKMP) += synclinkmp.o

+18 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,13 @@
		/*
		* Copyright (C) 2019 Axis Communications AB
		*
		* The console is useful for userspace applications which expect a console
		* device to work without modifications even when no console is available
		* or desired.
		*
		* In order to use this driver, you should redirect the console to this
		* TTY, or boot the kernel with console=ttynull.
		*
		* Based on ttyprintk.c:
		* Copyright (C) 2010 Samo Pogacnik
		*/
		@@ -59,6 +66,17 @@ static struct console ttynull_console = {
		.device = ttynull_device,
		};

		void __init register_ttynull_console(void)
		{
		if (!ttynull_driver)
		return;

		if (add_preferred_console(ttynull_console.name, 0, NULL))
		return;

		register_console(&ttynull_console);
		}

		static int __init ttynull_init(void)
		{
		struct tty_driver *driver;

+3 −0

Original line number	Diff line number	Diff line
		@@ -187,9 +187,12 @@ extern int braille_register_console(struct console *, int index,
		extern int braille_unregister_console(struct console *);
		#ifdef CONFIG_TTY
		extern void console_sysfs_notify(void);
		extern void register_ttynull_console(void);
		#else
		static inline void console_sysfs_notify(void)
		{ }
		static inline void register_ttynull_console(void)
		{ }
		#endif
		extern bool console_suspend_enabled;

+8 −2

Original line number	Diff line number	Diff line
		@@ -1480,9 +1480,15 @@ void __init console_on_rootfs(void)
		struct file *file = filp_open("/dev/console", O_RDWR, 0);

		if (IS_ERR(file)) {
		pr_err("Warning: unable to open an initial console.\n");
		pr_err("Warning: unable to open an initial console. Fallback to ttynull.\n");
		register_ttynull_console();

		file = filp_open("/dev/console", O_RDWR, 0);
		if (IS_ERR(file)) {
		pr_err("Warning: Failed to add ttynull console. No stdin, stdout, and stderr for the init process!\n");
		return;
		}
		}
		init_dup(file);
		init_dup(file);
		init_dup(file);