Doesn't Not Compute

My log of experiences with GNU/Linux and computers in general.

Acer Aspire One A0751h: Part Three

Acer Aspire One 751hWell, there is still some stuff that needs to be done with the Windows side of the netbook, such as installing an antivirus program and another firewall, and some deep tweaking, but as I’m not planning to use Vista any more often than I have to πŸ˜‰ I’m going to skip on to the good stuff: Arch Linux. :mrgreen:

The basic installation was pretty standard, so far as an Arch installation can be standard, so I won’t discuss much of the specifics. The Official Arch Linux Install Guide can handle that more than adequately. πŸ˜‰ I do think it’s good to mention, however, that I used the ext2 file system for /boot and ext4 for / and /home. I didn’t install syslog-ng because it writes the logs out to the hard drive — which wakes up the drive from its powersave mode.

Oh, right — power savings, I should probably put a note about that here, too. To save power on a laptop, there are certain things I want to have control of:

  • CPU frequency, if there is support for frequency scaling.
  • How often data is written to the hard drive, and thus
  • How long the hard drive stays in its sleep mode.
  • Ability to ‘Suspend’ the system at all.
  • Ability to ‘Hibernate’ the system (optional, I don’t really need this.)
  • Control screen brightness.
  • Use full screen resolution
  • Set the system to automatically Suspend when I close the lid.

I haven’t managed to get all of those working yet, but I do have command-line control of a few things. As root, after you have done any updates you need to do with pacman -Syu, execute this:

pacman -S acpitool laptop-mode-tools cpufrequtils

Now we can enable the cpufreq module

modprobe acpi-cpufreq

and control the CPU frequency. The Atom Z520 supports a power-saving 800MHz mode, a slightly faster 1.07GHz (which, oddly, I have to specify as 1 GHz), and a “speedy” 1.33GHz. I prefer longer battery life, so I set the frequency to minimum with

cpufreq-set -c0 -g powersave
cpufreq-set -c1 -g powersave

ensuring that the cpu is automatically put into the lowest frequency available.

Using two separate cpufreq-set statements is necessary because of the hyperthreading support — the CPU is seen as two separate processors.

If you want the frequency to increase when you need more processing power, and then return to a lower setting later, replace “powersave” with “ondemand”.

Note: The below was true at the time I wrote it. However, Arch Linux is a rolling-release distribution, and since the time I wrote this the suspend functions have ceased to…well, function. The machine will enter suspend-to-ram mode, but the screen will not awaken upon resume. My hypothesis is that this is because of the update to Xorg 1.7, but without the Xorg 1.6 PKGBUILDs I cannot test this. Consider the below historical information. — April 18, 2010.

Surprisingly, I didn’t need to do any extra work to get ‘Suspend’ working. Remember acpitool, which we installed earlier? It doesn’t just display the current battery charge remaining or the current tempreture — it also can send the machine into its sleep mode.

acpitool -s

On this machine, I haven’t had any problems suspending-to-ram or returning to normal operation with this method. πŸ™‚

That’s all for this entry, in the next one I’ll try to give a tutorial on how I got full resolution (1366×768) in both the framebuffer and Xorg — without the Poulsbo drivers. πŸ˜‰ I haven’t been able to control the brightnes of the screen that way, so I have toΒ  set with the Fn-Arrow combos while the GRUB menu is still being displayed, but at least it’s stable. I haven’t figured out hibernation either, but I really don’t have much need for that anyhow.


One response to “Acer Aspire One A0751h: Part Three

  1. Savannah October 17, 2009 at 6:51 am

    Awesome blog!

    I thought about starting my own blog too but I’m just too lazy so, I guess Ill just have to keep checking yours out.

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