Laptop power management support

[Matthew Garrett]

I've been doing some work on power management support. Note that this is
all highly experimental, so proceed with caution. It may eat your disks.

There's two parts to this - kernel support and userspace support. Add

deb http://www.srcf.ucam.org/~mjg59/laptops/ ./

to /etc/apt/sources.list and do

sudo apt-get install linux-image-2.6.9-1-386 acpi-support

First, if you're using the i810 video driver, edit
your /etc/X11/XF86Config-4 (or /etc/X11/xorg.conf if you're using Xorg)
and in the driver section add 

option "VBERestore" "true"

Now edit /boot/grub/menu.list. Find the # kopt line and add
resume=/dev/hdwhatever - it should point at your swap partition. For
reference, mine is

# kopt root=/dev/hda1 resume=/dev/hda2 ro

Now do sudo update-grub and reboot. The power button should now cause a
suspend to disk. Boot again and it should resume (there may be a
moderately long pause before the resume process starts at the moment - I
need to spend some time looking at that).

If that works, try pressing your laptop's sleep button (normally Fn
+Escape, Fn+F4 or something like that). Test this from X, not from the
console. With a bit of luck, various messages will fly past and the
machine will suspend to RAM. If the machine /doesn't/ suspend, please
follow up with information about the last few messages.

Now try pressing the power button again (on some machines, you may need
to hold it for a second or so). With rather more luck, the machine will
resume and you'll have an X desktop again. If it doesn't, please follow
up with the symptoms.

Known issues:

If mysqld is running, the suspend will be blocked. Stop it first.

Various machines refuse to resume from suspend to RAM, for reasons that
are currently entirely unclear. If your machine hangs with a blank
screen or simply reboots, then there's not a lot we can do right at the
moment (though in the former case, there is some further debugging which
can be carried out)

It's entirely possible that the laptop will resume but you won't have
any video support. Again, follow up with some hardware information.
-- 
Matthew Garrett | mjg59 at srcf.ucam.org