Re: PROBLEM: E6850 has an 8+ minute delay during boot

From: H. Peter Anvin
Date: Fri Dec 14 2007 - 19:39:42 EST


Arun Thomas wrote:
On Dec 14, 2007 2:01 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
Thomas Gleixner wrote:
The problem is caused by an SMI during the calibration routine. We
really need to come up with a solid solution which does not rely on
the periodic timer coming in, when there is something else (HPET,
pm_timer) available.
How long is the SMI?

Is there some instrumentation code somewhere which would allow me to
determine this? If not, can you give me some hints on where to add the
instrumentation code?

Well, the most obvious way to do it would be to run the calibration loop a large number of times, and observe the statistical variation. In particular, one should see a bi- or multimodal pattern where the difference between the peaks amount to the "lost time".

When we have a clue about the loss of time then we can figure out how to detect it.

-hpa
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