On Tue, 25 Sep 2012, Cyrill Gorcunov wrote: > So guys, if understand all things correctly it's supposed to use some > -1/-2 as initial @config value for unsupported events, right? Vince, > may not it be easier to use bit 19 as a flag of valid event and clear > it when you write to msr, thus we will not have to change "zero is reserved" > semantics (otoh i'm not sure if it won't become a problem somewhere in > future with some new cpu :)
Well, we wouldn't want to use a reserved bit. In theory we could re-use bit 22 (enable) or bit 20 (APIC enable) because those values should in theory be set elsewhere and could probably be masked out at an appropriate place. Is -2 really a valid cache event on Pentium 4? Though I admit patching all of the various PMU drivers to use -1/-2 rather than 0/-1 will be a pain, especially as many of them just default to 0 with no initialization currently. Vince Weaver vincent.wea...@maine.edu -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
