On Mon, 5 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 > > without first getting permission by using the "Eject Removable Devices" > > button. If you try to press that button while a program has a file open > > on the device, Windows says that you can't remove the device right now and > > advises you to try again later. > > So it's inconsistent in behavior, since this isn't how it handles > the same thing during resume-from-hibernate ... Obviously because Windows isn't aware of anything that happens during hibernate while the power is turned off. How could it possibly warn you about unplugging a device when it doesn't know whether you unplugged the device or not? If you describe the behavior as "Windows warns you whenever it learns that you ejected removable media without permission", then Windows _is_ consistent. > > However... I put the laptop into Hibernate mode. To be absolutely sure > > this was a true snapshot-poweroff-resume cycle, I also unplugged the power > > cord and removed the battery. Then I removed and replaced the USB device > > and restarted the laptop. Everything worked smoothly; the file remained > > open and the program was able to continue reading it, well past the point > > where the I/O buffers needed to be refilled. > > So basically there's a special case somewhere to treat _this_ disconnect > differently than other ones. Yes, there must be. > How does real suspend behave (like STR)? How does it handle cases where you > plug in a different instance of the same device ... example, different CF > card in a CF reader? Or when you move the device to another port? And > does XP behave identically? I'll try doing some of those experiments when I have a chance. > > If Windows ME can do this, Linux should be able to do it too. > > That argument can be stretched too far! Though from time to time I have > indeed wished for something more like a BSOD. An oops hidden in a logfile > that never gets flushed to disk, with an X desktop, gives no clues ... :) > > Linux certainly _could_ try to emulate up all the fault handling of some > version of Windows. But whether it _should_ is a different story. 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. What do other people on the PM list think? Alan Stern
