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

[Peter Zijlstra]

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.