Re: questions on ACPI
On Fri, 23 Jan 2004 19:11, Anders Ellenshøj Andersen <firstname.lastname@example.org>
> On Friday 23 January 2004 01:55, Russell Coker wrote:
> > > How do you then explain that without APM or ACPI, the fans do not start
> > > up leaving the system frozen after even small amounts of CPU load?
> > Your laptop is broken and will never work with DOS, memtest86, etc.
> Good point. I never actually tried running the kernel without either APM or
> ACPI. It was always wither either the one or the other. It is possible that
> using APM, the BIOS was really just controlling the fans independently from
> the OS. Whenever I replaced APM with ACPI the OS would be unusable after a
> few minuttes because the fans would not start up, but of course this could
> just as easily have ACPI that was broken.
Previously you said that when there was neither APM nor ACPI the fan would not
start. Now you say that when ACPI was enabled the fan would not start which
is a common symptom of broken ACPI (bugs like this are the reason I have
never tried ACPI and have no plans for trying it on hardware I own).
> Without any power management, the system wouldn't shut down using the
> poweroff command, so you have to manually shut it off. This is such a big
> annoyance that I never tried it without APM.
If you try testing these things or read the specs you will discover that APM
is only used for managing suspend/hibernation and power off. APM allows the
OS to instruct the hardware to enter a suspend or hibernation state or to
shut the machine down entirely. When the hardware decides that it is time to
suspend or hibernate (IE closing the lid, low battery, or Fn key press) then
if the OS has claimed support for APM then the hardware will ask the OS what
to do. Apmd will run some scripts if it's installed, and if all goes well
the operation will be permitted. The kernel should be able to provide
minimal APM functionality without apmd.
If the OS has not claimed APM support (DOS) then the hardware will do the
suspend/hibernation without any interaction with the OS. For some reason a
non-APM Linux system will not work with suspend/hibernation while DOS will.
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