On Fri, Aug 10, 2012 at 10:10:27AM +0200, Gerd Hoffmann wrote: > Hi, > > >>> (1) Use this patch (with alignment issue fixed of course). > >>> (2) Do a full kvmclock implementation. Feels a bit like overkill. > >>> (3) SeaBIOS can fallback to the PIT for timing on machines which > >>> have no TSC. We could do that too in case we detect kvm ... > >> > >> What sort of timeouts are these? If seconds, maybe the rtc would be best. > > > > I vote for 3 so nobody has to maintain kvmclock code in SeaBIOS and Gerd > > can fix the in-kernel PIT issues with GRUB (see Michaels message) while testing. > > (2) turned out to be not too bad when taking a shortcut: Go through an > enable/disable cycle each time we read the clock, then just grab > system_time. Not that efficient, but should be ok for seabios. Usually > it checks the clock when sitting around idle, waiting for something to > happen. And it simplifies the implementation alot as we can just skip > all the tsc frequency & delta calculations. > > Draft patch attached. Comments? Given the history of problems with kvmclock, would rather see it not being used for delays, if possible. Your shortcut gets rid of a class of problems, but there might be others (...). Isnt pmtimer ioport usable? 14MHz. Error handling in kvmclock_init is awkward. Thanks -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
