Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [suspend/resume] Re: userspace notification from module | Date | Sat, 16 Jan 2010 23:26:09 +0100 |
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On Saturday 16 January 2010, Pavel Machek wrote: > On Sat 2010-01-16 23:05:56, Rafael J. Wysocki wrote: > > On Saturday 16 January 2010, Pavel Machek wrote: > > > On Sat 2010-01-16 18:00:58, Stanislav Brabec wrote: > > > > Eric Miao wrote: > > > > > > > > > And the other way we may need to look into what API the current userland > > > > > apps on zaurus is depending on this 2.4 compatibility and make changes > > > > > slowly to those apps. > > > > > > > > I guess that 2.4 compatibility is not an issue. Most modern Zaurus > > > > distributions are even unable to run Sharp ROM compatible binaries. > > > > > > > > Distributions either stay on 2.4 kernel or use modern systems based on > > > > modern kernel 2.6 API. > > > > > > > > Distributions that decided to migrate to kernel 2.6 are far from > > > > finished state. Any change that allows to use modern applications using > > > > standard kernel API is welcome. > > > > > > There is no API involved. It is just ... if you leave zaurus in > > > init=/bin/bash mode, it must not kill the battery. Smart and > > > currently implemented way to do that is to suspend. > > > > IMHO it should just plain shutdown in that case. Suspending doesn't really > > solve the problem, because the battery is going to drain still. Unless you > > mean suspend=hibernate, but I guess you don't. > > As I explained before, power consumption on suspend and hibernate and > poweroff is equivalent on zaurus (7mA in all the cases -- sorry if I > said uA before). And because it has 1800mAh battery, it means that > even empty battery is going to last for a while. In practice, it works > very well. > > (There are other reasons, having to do with internal li-ion resistances > in aged and cold batteries.) > > > > That's counterexample to rjw, but it does not matter -- reasonable > > > userland should never ever hit that, in a same way PCs should not hit > > > emergency power cut... > > > > I don't really understand what you mean. The user space doesn't know the > > battery state if the kernel doesn't tell it, AFAICS, so how exactly can it > > predict the critical battery condition without the kernel notifying it? > > That was not the point I was trying to discuss. Yes, we need > kernel<->user notification of battery critical. > > But on zaurus, correct action is to suspend (not hibernate and not > poweroff) when battery is no longer able to supply enough power to > keep system alive.
Why not to poweroff (just asking, I don't know that hardware)?
I guess we should at least do our best to keep filesystems in a consistent state and suspend doesn't really guarantee this if the system remains on battery power afterwards.
Rafael
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