On Fri, Oct 24, 2014 at 03:13:19PM +0300, Alexander Shishkin wrote: > Peter Zijlstra <[email protected]> writes: > > > On Fri, Oct 24, 2014 at 11:22:20AM +0300, Alexander Shishkin wrote: > >> > The fact that the hardware cannot even tell you the supported mask is > >> > further fail. > > > >> The problem with this is that some bits go in groups, there'd be 2..3..4 > >> bit fields encoding desired packet frequency, for example. > > > > OK, so put the magic number in the big model array. > > I'm not sure I follow. These bits are reserved for the future, they can > potentially be whatever combinations of whatever. If we want to probe > around for valid combinations is to check everything in the range of > 0..2^43 (or something like that, the region reserved for packet enables) > and store all the valid ones, which sounds crazy.
I was assuming that the accepted bits are model specific, and we have this big model switch statement in perf_event_intel.c:intel_pmu_init(), so why not have something like x86_pmu.pt_magic_bitmask = 0xf00d in there? No need to probe in that case. That is the same thing we do for all unenumerated model specific things. -- 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/
