printk() - restore timestamp printing at console output

The output of the timestamps got lost with the conversion of the
kmsg buffer to records; restore the old behavior.

Document, that CONFIG_PRINTK_TIME now only controls the output of
the timestamps in the syslog() system call and on the console, and
not the recording of the timestamps.

Cc: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ef8192bc0c33..e11934177030 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -3,12 +3,16 @@ config PRINTK_TIME
         bool "Show timing information on printks"
         depends on PRINTK
         help
-          Selecting this option causes timing information to be
-          included in printk output.  This allows you to measure
-          the interval between kernel operations, including bootup
-          operations.  This is useful for identifying long delays
-          in kernel startup.  Or add printk.time=1 at boot-time.
-          See Documentation/kernel-parameters.txt
+          Selecting this option causes time stamps of the printk()
+          messages to be added to the output of the syslog() system
+          call and at the console.
+
+          The timestamp is always recorded internally, and exported
+          to /dev/kmsg. This flag just specifies if the timestamp should
+          be included, not that the timestamp is recorded.
+
+          The behavior is also controlled by the kernel command line
+          parameter printk.time=1. See Documentation/kernel-parameters.txt
 
 config DEFAULT_MESSAGE_LOGLEVEL
         int "Default message log level (1-7)"