On Wednesday 26 April 2006 17:38, Alan Stern wrote: > On Wed, 26 Apr 2006, Rafael J. Wysocki wrote: > > > > So under these circumstances, how does it hurt anything to reset the > > > resume device rather than to freeze it? > > > > It just shouldn't be necessary. Actually I think the resume device shouldn't > > be frozen too. > > Well, you wouldn't want it doing DMA to unknown memory areas while you're > trying to place the image data in those same areas, would you? And when > the image is reactivated, you wouldn't want the device generating > interrupt requests while its driver still thinks it is suspended. (Or if > it doesn't even have a driver in the image.) I think it'll always have a driver in the image, because we use it on suspend to save the image. Also IMHO, theoretically, the driver need not think the device is suspended. > And don't say that no resume device would ever do DMA or generate IRQs > while it was idle! What if it was a remote disk accessible via a network > interface? I think at least some devices may be told not to do DMA and/or generate IRQs without being reset or put into a low(er) power state. Ayway, as of today, we have no infrastructure allowing us to handle resume devices in a special way. However, if we decide to reset all devices before restoring the image, we'll probably make such things harder to implement in the future. Greetings, Rafael
