On Fri, 29 Oct 2004, Benjamin Herrenschmidt wrote: > On Thu, 2004-10-28 at 09:28 -0700, David Brownell wrote: > > > > > That is, there should be no "freeze the driver" request. > > All drivers except those for the swap device should just > > go straight into the relevant low power state, and stay. > > Just like STR. > > Not exactly... first the driver used for the swap device still need to > be "frozen" during the actual image snapshot. > > Second, for STD, we don't necessarily want to go through the burden of > putting all devices in low power if all you'll do next is to power the > machine off :) But that's not a big issue It is a bit of a big deal. Devices go into different states depending on whether we're suspending or shutting down. There have been problems on x86 with devices that didn't like to go into a low-power mode before the system turned off. (Don't recall the details, sorry). Not respeecting that could also mess with wake states. And, real power transitions cause a spike in power consumption. Not that it would be that much, but we would technically be wasting power and time to actually put things into a low-power state, bring them out, then put them back in it. If we have a separate power() method, we can do that independently of freezing-snapshotting-thawing; and actually suspending the system. And, we can re-use it for real shutdown/reboot and kexec. Thoughts? Pat
