On Tue, Jul 03, 2018 at 11:17:17AM +0200, Heiko Carstens wrote: > And to answer also your question: we don't use a regular load, since we > would have to use 'sacf' construct surrounding the load instruction which > would be much slower. > We have something like that implemented for the futex atomic ops, and we > could also implement something like that for this use case > (e.g. get_user_atomic()), if really needed.
/me digs out the s390-PoO PDF and understands.. this is because of the split user/kernel address space stuff. Fair enough.
