Fedora on a Dell

Fedora Core 2 on a Dell Inspiron 8600

ACPI Outline.

Latest Update -- December 28th 2005

The CPU Frequency Scaling Monitor applet is available in Fedora Core 4. It will allow you to view the currnet CPU speed and, if you have booted off a power supply, set the desired speed level. Simply right click a panel and select add to panel.

As my laptop is to be mainly used at home ACPI support would only be an added bonus. Having read pages on the web in regard to older laptop's and OS's I was surprised that the features I would like do not pose much of a probem. CPUspeed appears to control the Pentium M's speedstep feature quite well. Suspend to Memory didn't pose much of a problem after finding a good page on one of the Linux laptop sites. I have the acpi daemon running and the older apm daemon off. The only event the acpi daemon reacts to by default is to power off, or in the case the laptop has been suspended, resume.

ACPI Detail.

Speedstep.

In Fedora Core 2 the ACPI features are accessed largely through the /sys filesystem as opposed to the older /proc filesystem. To access the CPU features look under /sys/devices/system/cpu/cpu0/cpufreq. To determine the available frequencies that can be set run the following.

# cat /sys/devices/system/cpu/\
>cpu0/cpufreq/scaling_available_frequencies

To set the current speed use one of the available speeds determined above and run the following

# echo 1600000 > /sys/devices/system/cpu/\
>cpu0/cpufreq/scaling_setspeed>

To simply view the current speed run the following

# cat /sys/devices/system/cpu/\
cpu0/cpufreq/cpuinfo_cur_freq

However with cpuspeed running as a daemon the system will manage itself with little trouble. The chip will step down to 600000 and only increase when their is sufficient need. Running UT2004demo sees the chip jump to full speed but it steps back down once the game is stopped.

Events and Actions.

To enable various ACPI related features you need to add scripts to /etc/acpi/events and /etc/acpi/actions. The event scripts simply capture the event and point to a action script which contains the commands that you wish to run. A typical example is inserting the ac adaptor. To capture the event you would add the following to /etc/acpi/events in a file called ac_adaptor.

#Events for plug / unplug AC adapter

event=ac_adapter
action=/etc/acpi/actions/ac_adapter

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