ACPI vs APM?

[schwinn8]

After a lot of playing (ok, well it wasn't actually fun!) with my system, I seem to see that ACPI has a bad habit of loading many devices on one (or two) IRQs. This, of course, ends up causing problems with video cards (especially) and caused me many lockups. Anyway, I figured the AnandTech readers may be able to help answer some questions about ACPI and APM:

1) What is the difference between ACPI and APM? I thought one of the benefits of ACPI was to allow you to change IRQs of devices within Windows (hence the "Configuration" in there). I have tried this myself in APM and ACPI mode, but Windows 98SE would not allow me to change the IRQs of the two conflicting devices (video and ethernet in my specific case.) Am I mistaken in my understanding of the benefits of ACPI?

2) If IRQ sharing is not advised for certain devices, why doesn't the ACPI specification (or APM or whatever other "IRQ spec") have some way of telling Windows that the video card, for example, should not share an IRQ? Or, does this spec already exist and Microsoft is choosing to ignore it or implement it improperly?

Any other insights to ACPI and APM would be appreciated. I tried to get some information from some web searches, but they are not very helpful - most explanations simply defined the term, but didn't describe any technical pros/cons of each setup.

 

[AndyHui]

For Win2K and WinXP: Why do all my devices use one IRQ in Win2K and WinXP?

There's a brief explanation of ACPI in there.

The ACPI implementation under Win98SE is quite different, and so does not have the same ramifications as it does under Win2K/WinXP.

I happen to be in the middle of writing an article about APM vs ACPI, so watch out for it in the FAQs soon.

 

[schwinn8]

Thanks for the answer... I look forward to the FAQ!

Incidentally, it's interesting to note that MS states (in that first article) that they recommend telling the BIOS you do NOT have a PnP OS.... *sigh*


Thanks again!

 

[Kishkumen]

Andy, I am really interested in your ACPI vs APM faq as well. I am getting ready to install win2k on a new raid machine that I've put together and the thought of ACPI conflicting with and causing slow downs on my shiny, brand new hard drives and other devices makes me feel uneasy. Truth is, even after reading the existing faq on the issue, I'm still quite uneasy about what is really going on, which is better and above all why. I've heard that windows XP doesn't assign them to the same irq which strikes me as odd with all of its similarities to win2k. Still, however, I would much rather continue to get my moneys worth out of win2k rather than upgrade so soon.

 

[d33pt]

why dont you just turn off acpi.. i do that and i dont have any problems.