On Fri, 2017-04-14 at 21:37 +1000, Benjamin Herrenschmidt wrote: > On Thu, 2017-04-13 at 22:40 -0600, Logan Gunthorpe wrote: > > > > On 13/04/17 10:16 PM, Jason Gunthorpe wrote: > > > I'd suggest just detecting if there is any translation in bus > > > addresses anywhere and just hard disabling P2P on such systems. > > > > That's a fantastic suggestion. It simplifies things significantly. > > Unless there are any significant objections I think I will plan on > > doing > > that. > > I object. Note: It would also make your stuff fundamentally incompatible with KVM guest pass-through since KVM plays with remapping BARs all over the place. Ben. > > > On modern hardware with 64 bit BARs there is very little reason > > > to > > > have translation, so I think this is a legacy feature. > > > > Yes, p2pmem users are likely to be designing systems around it (ie > > JBOFs) and not trying to shoehorn it onto legacy architectures. > > > > At the very least, it makes sense to leave it out and if someone > > comes > > along who cares they can put in the effort to support the address > > translation. > > > > Thanks, > > > > Logan
