periodic wakeup during sleep? (thinking ahead)

[Tom Sylla]

Owen Williams wrote:
> Palm OS also has this problem, and their solution (AFAIK) is that every
> minute the OS awakes into light sleep and basically asks if anyone wants
> the OS to wake up all the way.  At this point the clock applet checks
> the time, and if there's < 1 minute left on the alarm, it wakes the OS
> up all the way.  Then it counts down the last seconds and triggers the
> alarm.

The OLPC platform is mostly an x86 PC, and it has the standard RTC of 
PC-land. Standard RTCs let you program an alarm to turn the system on at 
any time you specify. You don't need to wake up every once in a while, 
you just program the RTC when you want it to wake up the system, and it 
does so. (the kernel provides an interface to use the alarm) As Ivan 
said, the PM stuff isn't all defined yet, but as far as the hardware 
itself goes, alarms are extremely easy.