ACPI Advantages over APM

Ben2040 · Guru Joined: 07 May 2003 Posts: 445 Location: UK

Hi

I don't understand - why has the standard advanced to something that everyone seems to have trouble with (ACPI), from something that "just works"(APM). I have a real old Dell XPi and Fn+Suspend suspends, closing the lid suspends or just turns off the screen, the HDD powers down at user set times, along with screen on/off, screen brightness and all with different options whether on AC or battery power.

This is on both Windows 95 and Debian 3.0 without any other programs.

Whats up with that???

Ben

allucid · Veteran Joined: 02 Nov 2002 Posts: 1314 Location: atlanta

The main difference between APM and ACPI (as far as i know) is that with APM, most functionality is controlled by the BIOS and with ACPI almost everything is left up to the kernel. This is why APM seems to 'just work', because you don't have to configure everything since the BIOS takes care of it. ACPI can give you more control and you can make changes to ACPI without having to get a BIOS upgrade from the manufacturer.

For older machines ACPI might not even be supported as it is the newer standard.

[edit] more info here, here, here, and also here.

Ben2040 · Guru Joined: 07 May 2003 Posts: 445 Location: UK

Hi

Nice info - but there are no examples of "the BIOS messing it up" or not understanding "add-in cards". My ancient laptop (100Mhz/20Mb/2.1Gb) never suspends accidentely, even if I leave it downloading overnight. Also what (in lay mans terms) can you do with the ACPI system?

Ben

tactless · Posted: Sun Jul 25, 2004 12:07 am Post subject:

Well, the best example would be acpid, I guess. One can have the PC do all kinds of stuff, for example, before (or perhaps instead of) shutting down when the power button is tapped.
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nightm4re · Posted: Sun Jul 25, 2004 6:58 am Post subject:

if you have a laptop, you can do stuff like have the hard drives spin down and hte lcd turn off when you close the lid. things of that nature.
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Ben2040 · Guru Joined: 07 May 2003 Posts: 445 Location: UK

Hi

Well the LCD turns off when I close the lid (not the HDD), but I can press Fn+H to spin the HDD down manually - Is ACPI going to expand into new features (can't think of anything yet)

Ben