[coreboot] Timing via serial port

Kevin O'Connor kevin at koconnor.net
Sun Apr 19 14:56:05 CEST 2009

On Sun, Apr 19, 2009 at 11:40:07AM +0200, Carl-Daniel Hailfinger wrote:
> On 19.04.2009 04:23, Kevin O'Connor wrote:
> > then the problem goes away - coreboot takes only 1.8 seconds.
> Still, 1.8 seconds can surely be trimmed down further. Our early startup
> code has some variants performing totally nonsensical operations which
> easily account for 200 ms or more. (One variant does nothing except
> switch CAR on, fill the cache slowly, switch CAR off again and hope that
> CAR works although it is switched off.) The big problem here is that
> early startup is considered magic and the accumulated cruft is legendary.

That was with debugging on.  The timing script adjusts the numbers
with the cost of waiting for the serial port, but it doesn't account
for all the costs of generating the reports.

With debugging off, it looks like coreboot-v2 takes 1.2 seconds.  Of
that the 400ms for keyboard init looks to be the biggest time
consumer.  (Yes - both SeaBIOS and coreboot are initializing the


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