I'm not sure what all the sleep levels are, but I think s3 is sleep to
RAM, and S4 is sleep to disk.  Right now NetBSD doesn't have any support
for S4, and the question is, should  the support that it might have be
ripped out?
	The sysctl you're asking about exists in code starting with NetBSD-4
and if you set the variable to 3, your machine should sleep to ram and,
when you wake it up with the power button, it should come back to where it
was before you put it to sleep thusly.  There are /etc/powerd scripts which
can do this sysctl write for you, so you can get normal behavior like
closing the lid and having your laptop go to sleep.
	For my part, I'd like to see slee to disk supported at some point, so
ripping out what support alreadypotentially exists seems counter productive
from my perspective.  Having said that, I have no idea how hard this is to
implement, but having that functionality would be great.  My 5 year old
Windows XP  laptop does this, and I like the feature a lot even though I
never use Windows.  If I could do it with NetBSD, I'd be tickled pink
because it could mean I could get up and running on a laptop so much faster,
even one that had been sleeping for a couple of weeks.
-Brian
On Nov 12,  7:00am, Bernd Ernesti wrote:
} Subject: Re: ACPI S4BIOS support
} On Sun, Nov 11, 2007 at 07:34:59PM +0000, Joerg Sonnenberger wrote:
} > On Sun, Nov 11, 2007 at 07:59:04PM +0100, Bernd Ernesti wrote:
} > > On Sun, Nov 11, 2007 at 07:30:45PM +0100, Joerg Sonnenberger wrote:
} > > > Hi all,
} > > > is there someone out in NetBSD with hardware that supports S4BIOS?
} > > 
} > > How do I find that out?
} > 
} > I guess the simplest approach is to set a breakpoint on
} > enter_s4_with_bios and run sysctl -w machdep.sleep_state=4.
} > The current code falls back to S3 and should not hit DDB if it is
} > missing the bits that tell it that S4BIOS support is present.
} 
} You know that using buzz words doesn't make it easier to test it.
} 
} Whats S3?
} I know that there are some power levels, but I don't want to spend
} hours to find out what it does, after looking for S4BIOS and didn't
} easily find it.
} 
} And what version of NetBSD does it take to use machdep.sleep_state?
} 
} Please provide enough informations to make it easy to test it
} if you want some feedback (e.g. the breakpoint and so on).
} 
} Bernd
} 
>-- End of excerpt from Bernd Ernesti