Hi! > > ? No, I do not think we have any problems with temporary > > pointers. Memory snapshot is atomic (done on single CPU, with disabled > > interrupts, no DMAs). > > The problem I'm trying to point out is that it's _not_ atomic wrt "save > the device state". > > You've actually worked very hard to make "save device state" and "snapshot > memory" to be as atomic as possible - by having the device state save also > basically try to freeze the state. Agreed. > And I'm trying to change that. Okay, but I do not see why? You'd force me to do... > And that means that the resume must not restore any "temporary pointers". > > Now, a lot of hardware doesn't _have_ temporary pointers, but if it has > things like a DMA ring with pointers to buffers (network drivers do this, > for example), then you need to realize that if the that ring is _not_ > atomic wrt the memory snapshotting if packets were still coming in > (packets that you didn't even care about). ...some magic, involving driver knowing which pointers are temporary and which are not, possible leaking memory. > It's an inconvenience that needs a strategy, and the strategy can range > from "refuse to do networking during suspend if we're suspendign to disk" > to "various MM things to make it easier to handle" to "if you use > networking during the suspend, you migth possibly leak some memory". It's a pretty big inconvenience, and I do not see a point. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
