On 08/22/2018 01:42 PM, Mikulas Patocka wrote: > unsigned long flags = swpipl(IPL_MAX); > > - barrier(); > + mb(); Maybe, but I doubt it makes a difference in practice. The swpipl is a transition through PALcode, and the instruction queue will have been flushed into and out of PALmode. But of course the barrier shouldn't be required either. r~