Re: Low battery -> power down + clock set back to 1904-01-01
On Fri, 2004-01-23 at 22:35, Guido Guenther wrote:
> On Fri, Jan 23, 2004 at 11:32:46AM +0100, Michael Schmitz wrote:
> > I've had the same happen on occasion, and won't of course blame pmud for
> > it :-) Seriously, what seems to happen is the battery is lying about how
> > much charge is left, and runs out during sleep.
> Just for the record, I didn't look into this further:
> I had the clock reset to 1904 after hitting Magic-Sysrq+M (showMem)
> where the machine simply powered off and when hitting Magic-Syrrq+B
> (reboot).
Well, this is different.
The kernel continuously talks to the PMU. It happens asynchronously
at interrupt time. If for some reason, that communication is stopped
in the middle of a message transmission, the PMU times out and shuts
the machine down, losing the time (I suspect it resets itself, and
since it does the timekeeping as well...)
So a kernel hang or stopping it (with sysrq) in the middle of such
a message transmission can trigger that.
One fix would be to shield the sysrq stuff with pmu_suspend() or to
call pmu_poll in the sysrq code.
That's unrelated to the battery problem.
Ben.
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