On Fri, Apr 29, 2011 at 11:57 PM, Thomas Gleixner [off-list ref] wrote:

On Fri, 29 Apr 2011, Linus Walleij wrote:

quoted

Jonas ?berg has this pending patch that we call "boot time recorder".
What it does is basically start a free running timer before the
kernel is booted, e.g. in U-boot or even in the ROM of your
machine if you can.

If we need more finegrained sched_clock() before the
clocksource is up, a good approach would be to utilize
something like that for sched_clock up to that point, plus
it has the upside that [0.000000] is as close to electrical
power-on as possible.

Well, you can read out that value at the point the clocksource gets
installed so you have the time spent up to that point without adding
another facility, level of indirection ...

That too (one does not exclude the other), what I was getting at is that
systems may have something alredy running that is monotonic and
trustable, and would likely go into some early_timer() or similar familiar
kernel naming scheme. But no point in doing any of that sort now, let's
have jiffies for now and get that to work.

Thanks,
Linus Walleij