In fact, while it's never worded explicitely in the spec, it's always been strongly in the "spirit" of the architecture that the timebase and decrementer have a constant frequency.
The architecture mentions varying time base frequencies, and how to deal with this, actually. It makes no recommendations one way or the other. Fixed frequencies are easier for almost everything of course :-)
This is why processors like the 970 allow for an external sourcing for when they are used in setups where the various clocks are slewed for power management.
Clock spreading on the core clock is the bigger problem, lack of accuracy on the order of 1% is unacceptable for certain applications. Segher - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/