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    SubjectRe: [PATCH 1/6] UML - Deal with host time going backwards
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    On Tuesday 03 June 2008 04:07:09 pm Andrew Morton wrote:
    > On Tue, 03 Jun 2008 20:52:18 +0100
    >
    > Nix <nix@esperi.org.uk> wrote:
    > > On 3 Jun 2008, Daniel Hazelton said:
    > > > On Tuesday 03 June 2008 03:32:11 pm Andrew Morton wrote:
    > > >> On Tue, 3 Jun 2008 15:02:35 -0400
    > > >>
    > > >> Jeff Dike <jdike@addtoit.com> wrote:
    > > >> > Protection against the host's time going backwards - keep track of
    > > >> > the time at the last tick and if it's greater than the current time,
    > > >> > keep time stopped until the host catches up.
    > > >>
    > > >> Strange. What would cause the host's time (or at least UML's
    > > >> perception of it) to go backwards?
    > > >
    > > > A wild guess would be that the UML process is running "fast" at some
    > > > point and its expectation of the host's time is skewed forward because
    > > > of that.
    > >
    > > Quite so. Simply running ntp on the host (in slew-only mode, no less!)
    > > can cause this.
    > >
    > > > Another possibility is that the hosts clock got reset between the times
    > > > UML has checked it and the correction was a negative one.
    > >
    > > That too.
    >
    > So if I change the host's time by an hour, the time will not advance at all
    > on the guest for the next hour? Sounds suboptimal :)

    I agree. But like I said originally - it's a wild guess. I don't even know how
    accurate it is.

    > I suppose the guest should be running an ntp client synced to something
    > sane anyway?

    That might be helpful :)

    DRH

    --
    Dialup is like pissing through a pipette. Slow and excruciatingly painful.


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