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Date:      Sat, 09 Aug 2003 21:30:35 -0700
From:      "Kevin Oberman" <oberman@es.net>
To:        David Gilbert <dgilbert@dclg.ca>
Cc:        current@freebsd.org
Subject:   Re: ACPI battery state and resume not working on Inspiron 5150 
Message-ID:  <20030810043035.CAFA75D07@ptavv.es.net>
In-Reply-To: Message from David Gilbert <dgilbert@dclg.ca>  <16181.38818.239464.946522@canoe.velocet.net> 

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> From: David Gilbert <dgilbert@dclg.ca>
> Date: Sat, 9 Aug 2003 20:53:54 -0400
> 
> What does a hibernation partition look like?
> 
> My dell has a 31 meg partition that I havn't touched and my FreeBSD
> partition.

Most laptops have the capability of "sleeping" in two modes.

1. suspend where most of the system is powered off, but the memory is
kept on so that the system can pick up right where it left off (except
for drivers re-initing hardware) when the system is resumed.

2. Hibernate where the contents of memory and some system registers
are written ti a pore-allocated space on disk, usually a dedicated
partition. The boot is then tagged that the hibernation partition is
active and the systems is power completely off. On powering up, the
BIOS will detect that i=the system was in hibernation and reload the
memory and registers and resuming where the system left off. Hardware
must still be re-initialized and it's up to the drivers to handle
this.

Suspend is faster, but continues limited battery drain. Hibernation
takes a while to stop and start and requires a dedicated partition
(slice), but the system is totally off while in hibernation.

I don't know if all laptops support both, but every one I have used
does. IBM has a stand-alone tool on it's web site that creates a
hibernation partition on ThinkPads (which I use). You probably need to
check with the manufacturer of your system to see what is available.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net			Phone: +1 510 486-8634



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