On Wed, 2003-12-17 at 18:17, Lee Braiden wrote: > On Wednesday 17 Dec 2003 6:24 am, Benjamin Herrenschmidt wrote: > > CONFIG_RTC will definitely break a pmac > > I think I heard something about clock/timer problems on PPC a long time ago, > but could never track down an issue. Wouldn't it be best to remove RTC on > PPC or document the problem with a (read help) or something? > > Is the PPC RTC (as opposed to GENERIC_RTC) stuff automatically in there, or > something? Or is it this PPC_RTC that's broken?
Well... CONFIG_RTC enables the "PC style" RTC driver that taps IO ports to look for an RTC chip of the kind found in x86 machines. Such a chip doesn't exist on powermac and this random IO port tapping can actually crash the machine. CONFIG_PPC_RTC/CONFIG_GENERIC_RTC is a different driver that provides the /dev/rtc interface but relies on hooks provided by the platform code for actually getting/setting the RTC content. The PowerMac platform provides hooks for the different kind of RTC chips found on Macs (that is basically access to the RTC via via-cuda or via-pmu). CHRP or PReP machines should provide their own hooks, it's possible that what CHRP provides doesn't work properly on the Pegasos, in which case we'd have to fix this. Ben.