Which PowerPC BSP/libcpu to base new port on?

Stephen Holford SHolford at WESCAM.com
Mon Nov 25 14:06:39 UTC 2002


>>What kind of flaws?  Would the PIT be better suited in that case?

If you intend to use interrupt nesting then don't use the decrementor. 
It is masked and unmasked only with the EE bit, which means you can't 
mask it off while servicing higher priority interrupts if you have 
turned interrupts back on to allow nesting. (As a general rule, the 
timer interrupt that drives time-slicing should be the lowest priority 
interrupt in a multitasking OS). The PIT works nicely in this role for 
the 860 and 8260.

Steve Holford

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