Re: [PATCH 2/2] printk: Add boottime and real timestamps
From: Mark Salyzyn
Date: Tue Jul 25 2017 - 18:39:27 EST
On 07/25/2017 06:00 AM, Peter Zijlstra wrote:
On Tue, Jul 25, 2017 at 08:17:27AM -0400, Prarit Bhargava wrote:
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 5b1662ec546f..6cd38a25f8ea 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1,8 +1,8 @@
menu "printk and dmesg options"
config PRINTK_TIME
- int "Show timing information on printks (0-1)"
- range 0 1
+ int "Show timing information on printks (0-3)"
+ range 0 3
default "0"
depends on PRINTK
help
@@ -13,7 +13,8 @@ config PRINTK_TIME
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. 0 disables the
- timestamp and 1 uses the local clock.
+ timestamp and 1 uses the local clock, 2 uses the monotonic clock, and
+ 3 uses real clock.
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
choice
prompt "printk default clock"
default PRIMTK_TIME_DISABLE
help
goes here
config PRINTK_TIME_DISABLE
bool "Disabled"
help
goes here
config PRINTK_TIME_LOCAL
bool "local clock"
help
goes here
config PRINTK_TIME_MONO
bool "CLOCK_MONOTONIC"
help
goes here
config PRINTK_TIME_REAL
bool "CLOCK_REALTIME"
help
goes here
endchoice
config PRINTK_TIME
int
default 0 if PRINTK_TIME_DISABLE
default 1 if PRINTK_TIME_LOCAL
default 2 if PRINTK_TIME_MONO
default 3 if PRINTK_TIME_REAL
Although I must strongly discourage using REALTIME, DST will make
untangling your logs an absolute nightmare. I would simply not provide
it.
I agree with using select, ensures only valid values are landed. It does
mean that CONFIG_PRINTK_TIME in-effect gets deprecated.
REALTIME is always UTC in the kernel.
What about BOOTTIME?
-- Mark