DragonFly commits List (threaded) for 2009-05
Re: DragonFly-220.127.116.116.g136cd master sys/dev/acpica5 acpi_hpet.c
On Tue, May 5, 2009 at 11:59 PM, Matthew Dillon
> :No, not the actual count, but we will have to make sure the count is
> :monotonically increasing. So something like "not preserved" is not
> :> has to be reprogrammed after S3/S4 or at least recomputed by the code
> :> that reads back the RTC value.
> :Didn't aware how 8254 could be affected, 8254 document mentions
> :nothing about power management stuffs. But even if 8254's count is
> :not maintained at all, it seems to be less affected (+-1/15sec), since
> :major portion of the time is saved in dram.
> :If small gitch is acceptable, we could just add sys_cputimer
> :save/restore functions and call them before and after Sx state
> :Live Free or Die
> No, the actual timekeeping function cannot glitch. It is not
> acceptable. It will really mess up all sorts of things in the
> system even if it is just a forwards monotonic jump. Things like
The glitch will not be big, if we could save it just before entering
Sx state, I would expect no more than dozens of ticks.
> TCP timeouts, for example. Poor dntpd will also not be able to
I don't know whether things like TCP connections are still suppose to
work after Sx transition, since for Sx (x>=1), CPUs will not execute
> keep the time synchronized.
> Is there a way to know for sure whether a sleep state messes
> up the HPET? It sounds like it would be messy but it might be
> possible to use the 8254's free-running timer (our last-chance
> systimer) to check that the HPET is still functioning after
> a sleep state exits. If their approximate relative times do not
> match then then we will know that the HPET is being messed up
> by the sleep state.
The HPET document says it is not expected to work properly in Sx (x>=1) states.
> As long as the maximum sleep time is not more then 1/36 of a
Well, I think you probably could expect a box staying in Sx state for
more than an hour :). So except for saving/restoring timer's counter,
there are probably more things to do...
Live Free or Die