Re: [PATCH 0/2] printk, Add printk.clock kernel parameter [v2]

[Petr Mladek]

On Wed 2016-01-13 18:28:50, Thomas Gleixner wrote:
> You can solve the whole business by changing the timestamp in printk_log to
> 
>    u64	    mono;
>    u64	    offset_real;

This is not so easy because the structure is proceed by userspace tool,
e.g. crash, see log_buf_kexec_setup(). We would need to update all
the tools as well.


> and have a function which does:
> 
> u64 ktime_get_log_ts(u64 *offset_real)
> {
> 	*offset_real = tk_core.timekeeper.offs_real;
> 
> 	if (timekeeping_active)
> 		return ktime_get_mono_fast_ns();
> 	else
> 		return local_clock();
> }

A solution would be to apply the offset_real immediately. I wonder if
any tool expects the messages to be sorted by a monotonic clock. In
fact, it might be useful to see that some messages are disordered
against the real time, e.g. because of the leaf second.

Best Regards,
Petr