On Tue, Nov 08, 2011 at 03:12:27PM +0100, Peter Zijlstra wrote: > On Tue, 2011-11-08 at 15:54 +0200, Gleb Natapov wrote: > > Isn't it better to introduce mapping between ebx bits and architectural > > events and do for_each_set_bit loop? > > Probably, but I only thought of that halfway through ;-) > > > But I wouldn't want to introduce > > patch as below as part of this series. > > Well, since you're actually going to frob cpuid10.ebx bits we had better > deal with it properly. OK. We need to figure what is the proper way though. How about me introducing cpuid10_ebx with event_mask bitmask, mapping array, but not disabling events for now. > > > I do not want to introduce > > incidental regressions. For instance the patch below will introduce > > regression on my Nehalem cpu. It reports value 0x44 in cpuid10.ebx which > > means that unhalted_reference_cycles is not available (bit set means > > event is not available), but event still works! Actually it is listed as > > supported by the cpu in Table A-4 SDM 3B. Go figure. > > We'd better figure out why your machine says that. It could be we need > another quirk for the nehalem machines, it could be your BIOS is smoking > crack and there's nothing we can do about it. > I asked Intel a week (or so) ago. Waiting for an answer. Will try to find other machines with similar cpu to do more checks meanwhile. -- Gleb. -- 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
