On Mon, Jun 2, 2014 at 4:11 AM, intrigeri <intrigeri@???> wrote:
> Hi,
>
> AK wrote (02 Jun 2014 09:10:35 GMT) :
>> So you're saying that there's no daemon in the background that keeps
>> adjusting the clock? It only adjusts once?
>
> Exactly. https://tails.boum.org/contribute/design/Time_syncing/ has
> the details.
>
>> If that's the case, then yes it does increase monotonically, though
>> it you wouldn't be able to leave it on for long...
>
> I'm curious why :)
Simply because the clock will start losing accuracy over time? I mean
like a period of days,weeks, without shutting down, which I guess is
not the use case of Tails.
>
>>> I don't think it will always increase monotonically even after the
>>> initial sync. If the frequency of the cpu gets too fast, then the
>>> clock will be ahead, so it will be set backwards (or if the HTTPS
>>> servers are giving slightly early time). The adjtime() [1] call
>>> ensures that the time increases monotically by either temporarily
>>> increasing the CPU frequency to move it faster or decreasing it to
>>> move it slower and let the real time catch up (from what I
>>> understand).
>
> Well, adjtime() changes the system clock in a monotonic way, but one
> does not need adjtime() to have the system clock move forward in
> a monotonic way all by itself. That's a clock, after all :)
>
>>> So if you this set up, you can do an initial jump to set a Tails'
>>> user's clock if it's needed, and then they can restart and be sure
>>> that everything started and is still running with a smooth,
>>> monotonic clock.
>
> I'm afraid I don't get what you are suggesting. Note that Tails does
> not save the state of the software clock to the hardware clock.
>
Again, I guess it is a design principle to not change anything in the
hardware, so yeah it makes sense the way you do it. But it could be an
extra feature for advanced users who want more persistence.
>>> And maybe in the future you will find it useful.
>
> :)
>
> Cheers,
> --
> intrigeri
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