Experiences With a Dell Inspiron 4100

Hibernation

Summary: When set up properly, hibernation will work for Linux. Windows XP has its own hibernation method, and its own save file, which also works. I don't know, but I doubt, if XP can hibernate using the BIOS method.

The BIOS supports two styles of hibernation: all of memory and video RAM in one partition, or the initial segment in a small partition, continued to a plain file in another DOS partition. I don't know if FAT32 qualifies, but NTFS definitely doesn't, so the split partition method is not feasible on modern systems.

I recreated the save-to-disc partition. It is best to do this before setting up Windows and Linux, in case you make a mistake. Correct method:

• Download d5788807.exe from http://support.dell.com and execute it (on Windows, any version) producing a bootable floppy. (See below for an alternative.) (Credit to myronsussman <msussman@adelphia.net> on LDL for finding this file.) This has the same mks2d.exe that's on the Dell resource disc (Win98) for the Inspiron 3800.
• Compute the required size of the hibernation (s2d) partition. The official formula is (main + video RAM)*1.01 + 2 Mb, rounded up to the next whole cylinder. Be sure to use consistent units: RAM and cylinder sizes both in bytes, or both in Mb defined as 2^20 bytes. (Inconsistent units led me to have to re-do this procedure twice.) There is an example in the readme file for mks2d.exe (on the floppy) where they use 1.01*(main RAM + 4 Mb), but I think that one assumes a 1990 style graphics card (VGA, oooo how kewl!)
• Of course nothing can go wrong in this procedure :-) but just in case it would be a good idea to back up everything of value on the disc. I made total backups of my Linux partitions onto my server, 1.3 Gb of stuff, using these command lines:

  cd / ; tar clzf - . | rsh myserver "cat - > /var/upgrade/root.tgz"
  cd home ; tar clzf - . | rsh myserver "cat - > /var/upgrade/home.tgz"
  	

• Boot SuSE Linux (remember to specify disableapic). The following method may be dumb but having the GUI interface helps you avoid errors. Tell it you will install Linux from scratch, and you will partition the disc. Delete hda1 (Dell "break the seal" partition) and hda2 (original WinXP). These partition number assignments are for my system; substitute what's right for your system.
• Create the WinXP partition as hda2 with the correct size, starting however many cylinders from the beginning, leaving hda1 uncreated and unallocated. Create your Linux partition(s) if not done yet. After it writes the partition table back to disc (taking about 15 secs to do it), abort the installation, ignoring its complaints.
• Boot your floppy. There are two choices here: use the floppy from the first step, or use the Windows 98 rescue floppy plus the Inspiron 3800 CD. Execute ``mks2d.exe -f''. On the CD you will find it under \win98\suspend. (-f means do not use a continuation file.) The partition is allocated from the free space, and something is written slowly on every block.
• You need to install Windows before testing hibernation. Actually I think the requirement is that at least one partition be bootable and ``active'', and WinXP qualifies. LILO ignores the ``active'' bit. But don't test hibernation from Windows XP, which has its own large hibernation file (which you would have to enable; it isn't on by default). The SuSE Linux rescue system is a convenient guinea pig.
• To actually hibernate, press Fn-A. A message will appear on the screen. With 256 Mb of RAM it takes about 90 seconds to write to the disc (using non-DMA I/O) and the same to read it back in. There is an alarming period of about 15 seconds (writing and reading both) when the screen goes blank. Don't panic; be patient; let it finish.
• To really test hibernation, unplug the power supply and remove the battery for 15 seconds.
• To resume, remove bootable floppies and CD, and boot hda1. This assumes that you have used LILO to give yourself a menu (see my lilo.conf file). I didn't try this, but the WinXP multisystem booter should also work with Linux and probably will handle de-hibernation automatically.

If mks2d.exe claims it wants a filesystem but can't find one or is not allowed to use one due to -f, then your hibernation partition is too small. Calculate the size correctly, delete hda2, and reallocate it leaving more space for hda1. If you attempt to hibernate and the partition has not been set up by mks2d.exe, the BIOS will exude a message to the effect that the hibernation partition is incompatible with the BIOS and the BIOS needs to be upgraded (which is a lie). It will then suspend to RAM.

Needless to say, the above procedure is a distillation of what I actually did, in the process of which I trashed my Linux root partition twice. Under no circumstances use DOS fdisk.exe to manipulate the partition table of a disc with unallocated space at the beginning, because it will put your new partition at some random location within your Linux root.

Do not fail to de-hibernate if you have hibernated! Your filesystem will be in an active state, as if the system had crashed, and if you boot Linux then fsck will repair the filesystem. Then you will create or add to files. If you later de-hibernate, that instance will not be aware of the changes made and will trash your filesystem.

If you have a hibernating image that you want to remove, the correct procedure is to execute rms2d.exe, and then mks2d.exe again. The hibernation partition will have been made active, and this needs to be undone, otherwise the BIOS will refuse to use the partition.

It takes 90 seconds to hibernate. The BIOS is not too bright about estimating the remaining charge in the battery, and one time the BIOS initiated a ``critical suspend'' operation with 4% left (it thought), and didn't have enough juice to finish the job.