printk: implement support for extended console drivers

[sfrench/cifs-2.6.git] / Documentation / ABI / testing / dev-kmsg

diff --git a/Documentation/ABI/testing/dev-kmsg b/Documentation/ABI/testing/dev-kmsg
index bb820be48179000dd85472ca5d02286778880aeb..fff817efa508f529559ac199bc3b5507dfd7a325 100644 (file)
--- a/Documentation/ABI/testing/dev-kmsg
+++ b/Documentation/ABI/testing/dev-kmsg
@@ -98,4 +98,13 @@ Description: The /dev/kmsg character device node provides userspace access
                logic is used internally when messages are printed to the
                console, /proc/kmsg or the syslog() syscall.
 
+               By default, kernel tries to avoid fragments by concatenating
+               when it can and fragments are rare; however, when extended
+               console support is enabled, the in-kernel concatenation is
+               disabled and /dev/kmsg output will contain more fragments. If
+               the log consumer performs concatenation, the end result
+               should be the same. In the future, the in-kernel concatenation
+               may be removed entirely and /dev/kmsg users are recommended to
+               implement fragment handling.
+
 Users:         dmesg(1), userspace kernel log consumers