Re: [RFC PATCH v2] ftrace: support very early function tracing

[Peter Zijlstra]

On Wed, Nov 08, 2017 at 02:19:07PM -0500, Steven Rostedt wrote:
> On Wed, 8 Nov 2017 20:07:27 +0100
> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> > Depends on how early you need things; ideally you'd be able to use the
> 
> Well, he starts tracing at the entry of start_kernel(), would this
> handle that?

You'll have to run something first to initialize clocks in any case.
He's calling native_calibrate_cpu() (which of course if completely
broken for virt).

So you might as well setup the sched_clock() infra properly.