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    SubjectRe: A desktop environment[1] kernel wishlist
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    On Wed, 2014-10-22 at 13:04 -0400, Zygo Blaxell wrote:
    > On Tue, Oct 21, 2014 at 08:09:38PM +0200, Bastien Nocera wrote:
    > > On Tue, 2014-10-21 at 11:00 -0700, John Stultz wrote:
    > > > On Tue, Oct 21, 2014 at 10:14 AM, Bastien Nocera <hadess@hadess.net> wrote:
    > > > >> As for: 'Export of "wake reason" when the system wakes up (rtc alarm,
    > > > >> lid open, etc.) and wakealarm (/sys/class/rtc/foo/wakealarm)
    > > > >> documentation'
    > > > >>
    > > > >> Can you expand more on the rational for the need here? Is this for UI
    > > > >> for power debugging, or something else?
    > > > >
    > > > > No, it would be used for automating backups, or implementing
    > > > > suspend->hibernation transitions. For example, right before the machine
    > > > > suspends, I would schedule it to wake up in a hour. If I get woken up by
    > > > > the rtc alarm (and not by the user through a lid open), I might:
    > > > > - check that I'm plugged into the AC, it's night, and in the vicinity of
    > > > > the server that handles my backups and so backup the system.
    > > > > - check whether the battery is low, and hibernate the machine (if it
    > > > > supports it, obviously).
    > > > >
    > > > > We cannot do that if we can't make out whether the wake-up came from a
    > > > > user action, or the alarm we set.
    > > >
    > > > I suspect wakeup type reporting is maybe not the best way to go about
    > > > this, since there may be a number of causes for wakeups and they can
    > > > arrive closely together in different orders, which can result in
    > > > races.
    > > >
    > > > For instance, if the machine suspends, and sets an alarm to be woken
    > > > up at midnight to do a backup, if the user resumes their laptop at
    > > > 11:59:59, should the backup still proceed at midnight?
    > >
    > > No. And I would expect that we would get a wake up type of "power
    > > button" or "lid open" in this case.
    >
    > I have been using something like this for the last 7 years or so.
    > The relevant inputs are:
    >
    > 1. is the user present (is there recent input on HID devices,
    > keyboard/mouse, but ignore devices like light sensors, 3D
    > accelerometers, and ACPI virtual keys)?

    If the user woke the machine up through the power button, you wouldn't
    see that from user-space. You could detect that the lid was opened,
    because you have state.

    > 2. which network connection(s) are available to reach the
    > backup server?
    >
    > 3. how much power is available (if on battery, how much run
    > time left?)
    >
    > 4. what is the policy (do backups happen at a specific time
    > of day, or whenever they can?)
    >
    > 5. was a backup completed successfully in the last N hours?
    >
    > Note the absence of any information about the cause of recent
    > suspend/resume activity, or any input from suspend/resume at all.

    How do I tell my environment not to wake the screen up when the machine
    was woken up by an alarm I scheduled to launch a backup? Or not to
    resume audio playback when I get woken up to handle network events
    (through connected suspend, or Wake-On-(Wireless-)LAN)?



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