Hi Arjan, > -----Original Message----- > From: Van De Ven, Arjan [mailto:[email protected]] > Sent: Saturday, January 13, 2018 10:16 PM > To: David Woodhouse <[email protected]>; Kumar, Venkataramanan > <[email protected]>; H.J. Lu <[email protected]>; Jeff > Law <[email protected]>; Paul Turner <[email protected]>; Mallick, Asit K > <[email protected]> > Cc: Nagarajan, Muthu kumar raj <[email protected]>; > GCC Patches <[email protected]>; Martin Jambor > <[email protected]>; Uros Bizjak ([email protected]) > <[email protected]>; Jan Hubicka <[email protected]>; Dharmakan, Rohit arul raj > <[email protected]> > Subject: RE: [PATCH 2/5] x86: Add -mindirect-branch-loop= > > > > If everyone is ok, my suggestion is to use "lfence" as the default > > > loop filler for retpoline. > > can we do BOTH a pause and lfence. > (that way on cpu's where pause is the power stop, it works, and on cpus > where it's a fallthrough (AMD) it goes to the lfence) >
I checked with our Architect. Having just "pause" is the concern. It should also be fine for AMD to use "pause" followed by "lfence" in the loop of retpoline. Regards, Venkat.
