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    SubjectRe: [suspend/resume] Re: userspace notification from module
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    Dnia 2 stycznia 2010 19:26 	Bartłomiej Zimoń <uzi18@o2.pl> napisał(a):
    > Dnia 2 stycznia 2010 16:56 Daniel Borkmann <danborkmann@googlemail.com> napisał(a):
    > > Hi Andy,
    > >
    > > 2010/1/2 Andy Walls <awalls@radix.net>:
    > > > Why not:
    > > >
    > > > a. write a module that implements a device node that supports poll(),
    > > > and
    > > >
    > > > b. have a user space process select() on the fd for read or exception
    > > > notification
    > > >
    > > > ?
    > >
    > > This is, of course, another possible solution that is more "cleaner"
    > > than the one with the signals.
    > > Then, your userspace program would have another thread polling for the
    > > device node. Question is which timeout would be appropriate to be "CPU
    > > friendly" and to keep notification latency short?
    > >
    >
    > Just need as fast as possible solution and on the other hand acceptable for kernel sources.
    > Usually programs needs just to disconnect something or set one flag.
    > Even if program will have no time for this it could be enough just to send this precious info.
    >

    first draft: http://starowa.one.pl/~uzi/pld/pm-notify.c

    # tail -f /var/log/kernel |grep pm-notify
    Jan 2 21:37:19 topijna kernel: pm-notify: suspend prepare
    Jan 2 21:38:18 topijna kernel: pm-notify: suspend prepare
    Jan 2 21:39:05 topijna kernel: pm-notify: suspend prepare
    Jan 2 21:43:38 topijna kernel: pm-notify: suspend prepare
    Jan 2 21:51:31 topijna kernel: pm-notify: suspend prepare
    Jan 2 21:53:59 topijna kernel: pm-notify: hibernation prepare

    But dont know why have loop here:

    $ hexdump /dev/test
    0000000 0033 0000 0033 0000 0033 0000 0033 0000
    *
    31424480 0033 0000 0033 0000 0031 0000 0031 0000
    31424490 0031 0000 0031 0000 0031 0000 0031 0000
    *
    $

    Best regards.
    Barłomiej Zimoń
    PLD Linux, Kadu Team

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