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    SubjectRe: hibernate/suspend-to-disk: to turn power or not?
    On Sun 2008-07-13 18:26:36, David Fries wrote:
    > On Thu, Jan 31, 2008 at 03:40:30PM +0100, Pavel Machek wrote:
    > > > Back to the original question and a proposed solution.
    > > >
    > > > I'm looking at the uswsusp source (while the kernel compiles),
    > > > and have a question here. Is it possible to call some external
    > > > application (typically a shell script) to do the final work after
    > > > when the image has been written? I mean in principle - I
    > > > understand there are some limitations here, but I don't know
    > > > which exactly.
    > >
    > > No, you can't exec() anything. That would write mtime back to disk and
    > > cause badness.
    >
    > SysRq-U remounts the disks readonly. Why not make the disks readonly
    > once the kernel state is in swap, why not let any program run and give
    > an error to writes?

    IIRC sysrq-U does not contain all the locking that's neccessary to
    make it completely safe. OTOH, it tends to work...

    > I know, long dead thread, but I too would like to tell the UPS to turn
    > off once the system state is resting safely in swap. Currently my
    > modified apcupsd scripts tell the UPS to turn off, then tells the
    > kernel to hibernate, and hopes the kernel finishes in time. I would
    > much rather do things the other way, but `echo disk > /sys/power/disk`
    > doesn't return until power is back on if everything goes well.

    If you use s2disk, you can execute C code at the point you want...

    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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