On Fri, 2007-05-18 at 13:39 +0800, Dave Liu wrote: > > > Yes, on some implementations there can be other conditions that > > > make a decrementer exception go away; there is no contradiction > > > here (thankfully). My wording was sloppy. > > > > Some CPUs have the DEC exceptions basically edge triggered (yeah I know > > for example? > > > it sucks). That's why, among others, the IRQ soft-disable code has code > > to re-trigger DEC exceptions ASAP (by setting it to 1.. note that we > > could probably use 0 here, we've been a bit conservative).
I'm not 100% certain... Paulus thinks all the old 6xx are like that, and maybe POWER4. If I look at the oldest BookIV I can find (the 601), it says that an exception is generated when the MSB transitions from 0 to 1. It's not clear wether the exception sticks while that bit is 1 or is indeed considered as an "edge" event that gets cleared as soon as delivered. Ben. - 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/
