On Wednesday 10 November 2004 14:44, Benjamin Herrenschmidt wrote: > > > No reason there shouldn't be both. On the other hand, > > keep in mind that the typical case with selective suspend > > is going to be that usermode is there, and working just > > fine ... if you're concerned with shutdown sequences > > that need userspace to behave, one strategy would be > > to quiesce more intelligently: shutting down as much > > as possible *BEFORE* userspace can no longer assist. > > It's very difficult to predict. Any block device can be on > the VM path for example, or a network driver can be in the > way (NFS) etc... Where does "predict" come into it? There are basic integrity rules to follow, analagous to those which the driver model already handles. PCI bridges only suspend after devices on the other side. USB hubs only suspend after the devices connected to them. Shouldn't block devices not "freeze" until after there's no need to page/swap on them? That is, until after userspace is refrigerated. We seem to have a rather ad-hoc model of shutdown ordering; it's great that we can finally enforce constraints using bus topology, but that's not all there is. - Dave
