On Friday, 21 September 2007 21:45, Alan Stern wrote: > On Fri, 21 Sep 2007, Rafael J. Wysocki wrote: > > > > > Well, the problem is that apparently some systems (eg. my HP nx6325) expect us > > > > to execute the _PTS ACPI global control method before creating the image _and_ > > > > to execute acpi_enter_sleep_state(ACPI_STATE_S4) in order to finally put the > > > > system into the sleep state. In particular, on nx6325, if we don't do that, > > > > then after the restore the status of the AC power will not be reported > > > > correctly (and if you replace the battery while in the sleep state, the > > > > battery status will not be updated correctly after the restore). Similar > > > > issues have been reported for other machines. > > > > > > Suppose that instead of using ACPI S4 state at all, you instead just > > > power off. Yes, you'll lose wakeup event functionality, and flashy > > > LEDs, but doesn't this take care of the problem? > > > > Nope. > > > > > The firmware shouldn't see the hibernate as anything other than a shutdown > > > and reboot. > > > > Actually, this assumption is apparently wrong. > > One gets the impression that the hibernation image includes a memory > area used by the firmware. That could explain why devices need to be > in a low-power state when the image is created -- so that when the > image is restored, the firmware doesn't get confused about the device > states. > > It would also explain why the firmware sees > resume-from-power-off-hibernation as different from a regular reboot: > because its data area gets overwritten as part of the resume. > > In reality it's probably more complicated than this, with weird > interactions between the firmware and the various ACPI methods. > Nevertheless, the main idea seems valid. I guess so, but I'm not sure. The ACPI NVS area is explicitly marked as reserved and we don't save it. On x86_64 we don't save any memory areas marked as reserved and yet the above happens. Greetings, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
