tty: Add NULL TTY driver
If no console driver is enabled (or if a non-present driver is selected
with something like console=null in an attempt to disable the console),
opening /dev/console errors out, and init scripts and other userspace
code that relies on the existence of a console will fail. Symlinking
/dev/null to /dev/console does not solve the problem since /dev/null
does not behave like a real TTY.
To just provide a dummy console to userspace when no console driver is
available or desired, add a ttynull driver which simply discards all
writes. It can be chosen on the command line in the standard way, i.e.
with console=ttynull.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index 0ebb8d6..80f6576 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -374,6 +374,20 @@
there simply will be no early console output. This is true also
if you don't boot under a hypervisor at all.
+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 GOLDFISH_TTY
tristate "Goldfish TTY Driver"
depends on GOLDFISH