Re: Keyboard lockup with NetBSD5

[Ignatios Souvatzis <is%netbsd.org@localhost>]

On Fri, Nov 13, 2009 at 07:06:50PM +0100, Frank Wille wrote:
> Ignatios Souvatzis wrote:
> 
> > Michael, what was the reason to switch back to a counter-based delay
> > from the Gordon Ross style cpu-internal one I introduced in 1996 to
> > make Draco Rev. 4 work?
> 
> Does that mean it makes no sense for me to fix the current implementation,
> because it won't work with Draco Rev.4?

DraCo Rev 4. has no guaranteed CIA, - for the clock interupt, it has a 
freerunning counter instead - so the easiest and cleanest solution was
to copy the Sun3 method for DELAY, which was a calibrated counter at a
cache-aligned position, (initialized to the value for the fastest CPU of
each type, and calibrated by the clock device at early initialization.)
This way, it was independent of additional hardware.

I did not look closely at the timecounter implementation - I've always
meant to, but didn't find the time - but I never suspected it would 
replace the DELAY routine. There might be definite reasons why the
loop method is bad for timecounters, but in that case, somebody should
document them.

        -is
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