diff options
| -rw-r--r-- | Documentation/admin-guide/serial-console.rst | 4 | ||||
| -rw-r--r-- | drivers/tty/Kconfig | 19 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 5 |
3 files changed, 26 insertions, 2 deletions
diff --git a/Documentation/admin-guide/serial-console.rst b/Documentation/admin-guide/serial-console.rst index a3dfc2c66e01..1609e7479249 100644 --- a/Documentation/admin-guide/serial-console.rst +++ b/Documentation/admin-guide/serial-console.rst @@ -78,7 +78,9 @@ If no console device is specified, the first device found capable of acting as a system console will be used. At this time, the system first looks for a VGA card and then for a serial port. So if you don't have a VGA card in your system the first serial port will automatically -become the console. +become the console, unless the kernel is configured with the +CONFIG_NULL_TTY_DEFAULT_CONSOLE option, then it will default to using the +ttynull device. You will need to create a new device to use ``/dev/console``. The official ``/dev/console`` is now character device 5,1. diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig index 63a494d36a1f..7fb81bbaee60 100644 --- a/drivers/tty/Kconfig +++ b/drivers/tty/Kconfig @@ -383,7 +383,24 @@ config NULL_TTY available or desired. In order to use this driver, you should redirect the console to this - TTY, or boot the kernel with console=ttynull. + TTY, boot the kernel with console=ttynull, or enable + NULL_TTY_DEFAULT_CONSOLE. + + If unsure, say N. + +config NULL_TTY_DEFAULT_CONSOLE + bool "Support for console on ttynull" + depends on NULL_TTY=y && !VT_CONSOLE + help + Say Y here if you want the NULL TTY to be used as a /dev/console + device by default. + + For example, it might be useful to prevent a VT-less kernel from + writing the system log to a random device connected to the serial + port. + + Another console driver still might get preferred via the command + line, SPCR, or the device tree. If unsure, say N. diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 07668433644b..2590498d8353 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -4277,6 +4277,11 @@ void __init console_init(void) initcall_t call; initcall_entry_t *ce; +#ifdef CONFIG_NULL_TTY_DEFAULT_CONSOLE + if (!console_set_on_cmdline) + add_preferred_console("ttynull", 0, NULL); +#endif + /* Setup the default TTY line discipline. */ n_tty_init(); |