On Wed, 17 Aug 2016, Peter Zijlstra wrote: > Hurm.. I never considered using RESET with rdpmc(). The typical usage of > rdpmc() I considered is something like:
I'm finally trying to hook up PAPI to properly use rdpmc and PAPI likes to use IOC_RESET in various places. I can just special case to not do so when in rdpmc mode, but I got curious if RESET was expected to work. > But the rdpmc user function should: > ... > > Which sign-extends the RDPMC result and adds it to userpg->offset, > resulting in a positive number again. I will have to check to see if PAPI is using the proper code. What happens is the procesed result has bit 49 set for some reason, so the results are 2^49 too big. I've been trying to track it down, but the PAPI code is a bit of a mess (to put it mildly). Vince
