Hi Alan, On Fri, Jun 22, 2018 at 03:11:37PM -0400, Alan Stern wrote: > On Fri, 22 Jun 2018, Will Deacon wrote: > > On Fri, Jun 22, 2018 at 02:09:04PM -0400, Alan Stern wrote: > > > On Fri, 22 Jun 2018, Will Deacon wrote: > > > > Could we drop the acquire/release stuff from the patch and limit this > > > > change > > > > to locking instead? > > > > > > The LKMM uses the same CAT code for acquire/release and lock/unlock. > > > (In essence, it considers a lock to be an acquire and an unlock to be a > > > release; everything else follows from that.) Treating one differently > > > from the other in these tests would require some significant changes. > > > It wouldn't be easy. > > > > It would be boring if it was easy ;) I think this is a case of the tail > > wagging the dog. > > > > Paul -- please can you drop this patch until we've resolved this discussion? > > Agreed. It sounds like we'll need two versions of the Rel and Acq sets > in the memory model; one for RCpc and one for RCsc. smp_load_acquire > and smp_store_release will use the former, and locking will use the > latter. > > Would it suffice to have this duplication just for release, using a > single version of acquire? What would happen on ARMv8 or RISC-V if an > RCsc release was read by an RCpc acquire? Or vice versa?
On Arm, RCsc release can forward to an RCpc acquire. We don't have an RCpc release instruction. Will
