Re: [PATCH 2/2] printk: Add boottime and real timestamps

Peter Zijlstra
2017-07-25T13:01:34Z

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.