On Tue, 6 Sep 2005, David Brownell wrote: > > > > With the USB device, things are more interesting. If you unplug the > > > > device (even while it's not in use), Windows warns you not to do this > > > > ... > > > > > > So it's inconsistent in behavior, since this isn't how it handles > > > the same thing during resume-from-hibernate ... > > > > ... > > If you describe the behavior as "Windows warns you whenever it learns that > > you ejected removable media without permission", then Windows _is_ > > consistent. > > No, it's inconsistent ... when you ejected the media before that > resume-from-snapshot, it could tell. And it ignored it, even though > you'd not told Windows you were going to do that. It sounds like we've got a failure to communicate. There were two experiments. In the first, I simply unplugged the device. Windows did detect this and did warn me. In the second experiment, I first did the snapshot-and-poweroff, then removed the device, then replaced the device, then did resume-from-snapshot. In that experiment Windows could _not_ tell and did not warn me. In none of the experiments was there a case where Windows could have realized that I unplugged the device and failed to warn me about it. > > I say this is a case where we should try, at least to some extent; users > > will feel that "Powerdown-swsusp automatically removes all hot-pluggable > > devices" is too Draconian. > > The simple solution is to use _real_ suspend states if you're going > to expect real suspend/resume behavior ... :) It will probably be easier to add the code needed to verify devices and media after restore-from-snapshot than it would be to educate users about the difference between suspend/resume vs. snapshot/restore! :-) > Note that for things like HID devices (mice etc), users rarely notice > this since the HID driver masks enumeration through /dev/input/mice. Yes, certainly. Mostly I'm concerned about storage devices. Although the same concerns affect other things too, like audio/video devices. > Also, that we've been aiming at that "removes devices" as the default > for drivers without suspend()/resume() support, because it's the ONLY > choice that's both reliable (all drivers can handle it) and safe (since > users and applications must already handle "live" unplug). Yes. Eventually it would be good to get suspend/resume support into all the drivers that could stand to benefit from it. Alan Stern
