tty: add 'active' sysfs attribute to tty0 and console device
tty: add 'active' sysfs attribute to tty0 and console device
Userspace can query the actual virtual console, and the configured
console devices behind /dev/tt0 and /dev/console.
The last entry in the list of devices is the active device, analog
to the console= kernel command line option.
The attribute supports poll(), which is raised when the virtual
console is changed or /dev/console is reconfigured.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty
new file mode 100644
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--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-tty
@@ -0,0 +1,19 @@
+What: /sys/class/tty/console/active
+Date: Nov 2010
+Contact: Kay Sievers <kay.sievers@vrfy.org>
+Description:
+ Shows the list of currently configured
+ console devices, like 'tty1 ttyS0'.
+ The last entry in the file is the active
+ device connected to /dev/console.
+ The file supports poll() to detect virtual
+ console switches.
+
+What: /sys/class/tty/tty0/active
+Date: Nov 2010
+Contact: Kay Sievers <kay.sievers@vrfy.org>
+Description:
+ Shows the currently active virtual console
+ device, like 'tty1'.
+ The file supports poll() to detect virtual
+ console switches.