CrunchBang Linux on the Acer C720 Chromebook

This is a guide for installing and configuring CrunchBang Linux on the Acer C720 Chromebook. Note that this method, unlike Crouton or Chrubuntu, is for those who want to wipe ChromeOS and just run Linux. The majority of the information is combined from various sources and I created this as a central reference.

I have the C720-2800 model, which has a non-touch matte screen, 16GB SSD, and 4GB RAM. This guide should apply to most if not all C720 models, though you may have to look elsewhere for troubleshooting touchscreen support.

Any comments or corrections, no matter how big or small, are certainly welcome. Please just submit an issue or a pull request.

Update (2014 Feb 1): I have been running this setup for about 2 weeks and everything has been great. Battery life is around 7-9 hours. Suspending it overnight will only run a few percent off the battery. Having 5-10 Chrome tabs open plus a couple terminals uses about 1.5GB of RAM, and this is after about a week of no reboots (just suspends). Installed all the scientific computing tools I need (R, RStudio, TeX Live, Git, Sublime Text 2, Dropbox) and am only at ~6.5GB of disk usage. Browsing is responsive and I am even able to do light scientific computing. I no longer have to worry about bringing a charger with me to get in a full day of work.

Putting Chromebook in developer mode

This step is needed to make more fundamental changes to your machine. Installing another OS definitely falls in that category.

Steps:

Boot up Chromebook as you normally would, login, and install all updates (not sure if this is necessary but can't hurt)
Press esc-f3-powerbutton to get to white splash screen
Press ctrl-D to get to "warning" splash screen
Press enter to confirm
Press ctrl-D again to boot ChromeOS in developer mode

Source: Chromium.org Acer C720 site

Enable booting from a USB drive

Booting from a USB drive is not enabled by default. Steps to enable:

Make sure you are logged in under developer mode
Press ctrl-alt-T to bring up crosh in a tab
Type shell to bring up the shell
Type in the following to enable booting from a USB drive
```
sudo su
crossystem dev_boot_usb=1 dev_boot_legacy=1
```

Note: if you have upgraded your machine's SSD you will need to install ChromeOS on it first and perform the above steps.

Installation

Basically the key is to modify one of the boot parameters with mem=1536m, or else you will get a "not enough memory" error when you try to install or even run a live session.

Create CrunchBang .iso (64-bit) using Universal USB Installer
Reboot computer with USB drive plugged in
At white splash screen press ctrl-L (note, NOT ctrl-D) to boot from USB drive
Highlight "Install" option (don't select it yet!)
Press Tab, which will bring up a prompt at the bottom of your screen. Add a space to the end of the command and then add
```
mem=1536m
```
Hit enter to begin installation

Rest assured this will not affect the amount of memory available to your system once everything is installed. For example, I have the 4GB RAM Acer C720 and all of my RAM was available to me.

Also NOTE: once CrunchBang is installed, when you turn on your computer you will see a white splash screen. Continue using ctrl-L instead of ctrl-D to fire up GRUB, from where you can then boot up CrunchBang. Do NOT hit the space bar and proceed, or your system may be wiped.

Sources: CrunchBang forum post (post #8 - actually uses mem=1075m; either one should work) and Arch Linux Acer C720 wiki

Getting the touchpad working

CrunchBang Waldorf uses a fairly old kernel (3.2) so we need to update the kernel, and then run a patching script.

UPDATE (2014 July 7): Many users have had issues with this step, largely since previous versions of this guide recommended using sudo apt-get dist-upgrade with the jessie repos, which will upgrade your kernel to whichever one is currently in the Debian Testing release. However, sometimes a kernel that is "too new" may break compatibility with the touchpad. Since the 3.12 kernel is confirmed to work with the touchpad, I recommend just upgrading to that one via backports, rather than risk having incompatibilities with whichever the latest jessie kernel is.

Below are the steps I recommend.

Add the following lines to /etc/apt/sources.list:

deb http://http.debian.net/debian wheezy-backports main
deb-src http://http.debian.net/debian wheezy-backports main

Run sudo apt-get update to download list of upgrades
Run sudo apt-get install linux-image-3.12-0.bpo.1-amd64 -t wheezy-backports to upgrade your kernel. The -t wheezy-backports is necessary so that a initramfs-tools dependency will also be upgraded
Reboot. Your kernel should now be upgraded to 3.12 (you can double check using uname -r)
Run the c720crunchbangtp_v3 script script
Reboot. Touchpad should be working.

If you want to instead use kernel 3.13, note that the file chromeos_laptop.c was moved from drivers/platform/x86 to drivers/platform/chrome. Thus, please use the c720crunchbangtp_v2 script instead. I haven't personally tested this yet though, so feel free to report issues with this.

Source: Benson Leung's patches. Comment in reddit.com/r/CrunchBang (see post by user ngorgi). CrunchBang forums and Debian forums for updating kernel via backports. Thanks to users jonwalch, Akko1, rofellos51, and chislon for contributing issues and fixes here.

Improving the touchpad's performance

These are more personal preferences. Once the touchpad is working via the above steps, some may find the touchpad to still be a bit unresponsive. You can test out touchpad settings (all changes disappear after a restart) using synclient in the terminal. Type synclient to see a list of touchpad settings and use man synaptics for more detailed descriptions of what each setting does. Temporarily try out a setting using e.g. synclient FingerHigh=10.

Once you figure out your preferred synclient settings, list them in /home/username/.config/openbox/autostart (change "username" to your username) along with the existing synclient calls (around line 52).

Change touchpad to trackpad on line 51 (if necessary)
Change VertEdgeScroll=1 to VertEdgeScroll=0. This will disable edge scrolling. I prefer two-finger scrolling.
Add the following:
```
synclient AreaRightEdge=850 &
synclient AreaLeftEdge=50 &
synclient TapButton1=1 &
synclient TapButton2=3 &
synclient TapButton3=2 &
synclient FingerHigh=10 &
synclient FingerLow=10 &
synclient MaxTapMove=20 &
```
The first two options disable the left and right edge slivers - I found this helped with reducing accidental touchpad clicks without compromising usability. The next three TapButton options map single, double, triple finger taps to what are typically left, right, middle mouse buttons respectively. The next two FingerHigh/Low options adjust touchpad sensitivity to my liking. The last MaxTapMove option reduces the maximum finger movement allowed to still register as a tap - I added this mainly so short two-finger swipes are not detected as two-finger taps too.

See the autostart file in this repository for the full, edited file with my preferred settings.

Fixing wireless, synaptic, and others

Once the kernel is updated, GTK+ (graphics-related toolkit) causes issues with the default Waldorf theme, leading to segmentation faults for some programs. Notably, nm-applet (the wireless icon in the taskbar) and synaptic (package manager) are among the affected.

Wireless still works, but it would be nice to have the nm-applet GUI to make changes. To bring it back (and fix segfaults for other programs too), just select a theme other than Waldorf. This needs to be done as both normal user and sudo though. In terminal:

lxappearance

Select a theme other than Waldorf, apply and close

sudo lxappearance

Select a theme other than Waldorf, apply and close. I chose "Murrine-Light". alt-F2 and then run nm-applet.

Not a very elegant solution but it works. This also has the added benefit of fixing synaptic and other programs. For more technical details see the second link below.

NOTE (2014 Feb 5): User jsharf has reported that they had Wi-Fi performance issues after installing CrunchBang. The issue was fixed by disabling hardware encryption by adding the line options ath9k nohwcrypt=1 to /etc/modprobe.d/ath9k.conf and rebooting. (Source)

Source: CrunchBang forum post and another CrunchBang forum post

Fixing suspend

UPDATE (2014 May 4): As per user chislon's note, a Reddit user has posted a fix for those using kernel 3.13. For older kernel 3.12, the below instructions should still work.

Steps:

Update the rc.local file in /etc to look like the version in this repository. Check the history for the original version if curious. Basically you add the following lines to the file:

echo EHCI > /proc/acpi/wakeup
echo HDEF > /proc/acpi/wakeup
echo XHCI > /proc/acpi/wakeup
echo LID0 > /proc/acpi/wakeup
echo TPAD > /proc/acpi/wakeup
echo TSCR > /proc/acpi/wakeup
echo 300 > /sys/class/backlight/intel_backlight/brightness
rfkill block bluetooth
/etc/init.d/bluetooth stop

Create a 05_sound file in /etc/pm/sleep.d using the file of the same name in this repository. Then make the file executable by running
```
sudo chmod +x /etc/pm/sleep.d/05_sound
```

In /etc/default/grub, replace the line

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash add_efi_memmap boot=local noresume noswap i915.modeset=1 tpm_tis.force=1 tpm_tis.interrupts=0 nmi_watchdog=panic,lapic"

And then update grub by entering sudo update-grub in the terminal.

The last step by itself will kind of fix suspend in that the first time you close the lid everything will come back fine when you open the lid back up. However, if you then close the lid again, it will only lock the screen rather than suspend. Plus, you may also have issues trying to shut down the system. The first two steps will fix this problem to allow "unlimited suspends and resumes". Others reported issues with USB and sound after resuming. Mine worked fine, possibly because I am on a newer kernel (3.12).

Source: Pedro Larroy's Google+ post (make sure to check Mike Lim's comments too) and Arch Linux forums

Sound keyboard shortcuts

We combine the highly customizable Openbox keyboard shortcuts with the command-line amixer function. You can manually toggle mute from the command line with amixer sset Master toggle and adjust sound up and down by 5% increments using amixer sset Master 5%+ unmute and amixer sset Master 5%- unmute. The unmute part is optional: leaving it in means that if you adjust the sound while muted, you will automatically unmute. Of course you can also change the 5% to be coarser or finer.

Since it is inconvenient to use the command line each time you want to adjust sound, most will want to map them to keyboard shortcuts. Even though the first row of keys have shortcut (brightness, volume, etc.) icons on them, they in fact physically trigger F1-F10 signals (note there are no F11 or F12 keys). To see this, execute xev at the terminal to start a program that captures and outputs key press signals.

I prefer to hold down the Super key (physically located where Caps Lock is usually found but sends the same signal as the Windows key) while hitting F8-F10 to trigger the volume shortcuts. In other words, the following shortcuts:

Toggle mute: Super-F8
Volume down (and unmute if needed): Super-F9
Volume up (and unmute if needed): Super-F10

Instructions for creating these shortcuts are below:

amixer should be installed by default. If not (to check, just type amixer into the terminal and see if you get an error) then install it with sudo apt-get install amixer

In the /home/username/.config/openbox/rc.xml file, place the following code chunk between <keyboard> and </keyboard>:

    <keybind key="W-F8">
      <action name="Execute">
        <command>amixer sset Master toggle</command>
      </action>
    </keybind>
    <keybind key="W-F9">
      <action name="Execute">
        <command>amixer sset Master 5%- unmute</command>
      </action>
    </keybind>
    <keybind key="W-F10">
      <action name="Execute">
        <command>amixer sset Master 5%+ unmute</command>
      </action>
    </keybind>

Make sure you restart Openbox (Super-Space ==> Settings ==> Openbox ==> Restart) to put the changes into effect.

See the rc.xml file in this repository for the full, edited file (will also contain modifications for all other shortcuts mentioned in this guide).

Source: CrunchBang forums (slightly modified)

Brightness keyboard shortcuts

Just like the sound shortcuts, we edit the rc.xml file, but instead of amixer we will use xbacklight. A side note on xbacklight versus xrandr, for those curious:

There are two options I researched: xrandr and xbacklight. According to xrandr's man page and my own testing, xbacklight is preferred. This is because xrandr only adjusts brightness via software while xbacklight actually makes hardware changes. One way to see this is to compare xrandr --output 0x46 --brightness 0 with xbacklight -set 0. Both claim to set the rightness to zero but xrandr only makes everything black while it is clear that the backlight is still on. It appears to only change the gamma settings without physically dimming the backlight. The xbacklight method actually appears to alter the intensity of the backlight.

To try xrandr for yourself, replace 0x42 with your monitor's identification code (which can be found in the "Screen 0" entry after using xrandr --verbose). One other way to verify that xbacklight is better is to look at how /sys/class/backlight/intel_backlight/brightness changes. Its value does not change when using xrandr, but it does when using xbacklight.

The below steps will make the following shortcuts:

Brightness down: Super-F6
Brightness up: Super-F7

Steps:

Install xbacklight using sudo apt-get install xbacklight

Add the following between <keyboard> and </keyboard> in rc.xml.

    <keybind key="W-F6">
      <action name="Execute">
        <command>xbacklight - 10</command>
      </action>
    </keybind>
    <keybind key="W-F7">
      <action name="Execute">
        <command>xbacklight + 10</command>
      </action>
    </keybind>

Restart Openbox (Super-Space ==> Settings ==> Openbox ==> Restart) to put the changes into effect.

Note that one current issue with this method is that the numerical value does not linearly scale with perceived brightness. In other words, going from 1% to 5% results in roughly the same perceived brightness increase as going from 5% to 50%. The above link gives a solution to the problem, though I have not personally tested it.

See the rc.xml file in this repository for the full, edited file (will also contain modifications for all other shortcuts mentioned in this guide).

Keyboard shortcuts for Page-Up, Page-Down, Home, End, Delete, Caps Lock

The C720 keyboard does not have keys for these functions, so I use the following mappings. The page-up/down and home/end keys are the same default shortcuts that ChromeOS uses. Delete and caps lock are different:

Page-up: alt-up
Page-down: alt-down
Home: ctrl-alt-up
End: ctrl-alt-down
Delete: shift-backspace (won't be able to hold it down though)
Caps lock: super-F4 (very important for yelling on the internet)

To do so we will take advantage of xdotool, which allows you to run keyboard or mouse events from the terminal. Steps:

Install xdotool if you don't already have it. Use sudo apt-get install xdotool if you need to install it.
ctrl-alt-up and ctrl-alt-down are already mapped to something else in rc.xml that I don't use (they are mapped to workspace switching, but I prefer ctrl-alt-left and ctrl-alt-righ for workspace switching anyway), so comment them out. Roughly lines 196-207, near the start of the <keyboard> section. Comment a chunk by enclosing the lines between

Add the following between <keyboard> and </keyboard> in rc.xml.

    <keybind key="A-Up">
      <action name="Execute">
        <command>xdotool key --clearmodifiers Page_Up</command>
      </action>
    </keybind>
    <keybind key="A-Down">
      <action name="Execute">
        <command>xdotool key --clearmodifiers Page_Down</command>
    </keybind>
      </action>
    <keybind key="C-A-Up">
      <action name="Execute">
        <command>xdotool key --clearmodifiers Home</command>
      </action>
    </keybind>
    <keybind key="C-A-Down">
      <action name="Execute">
        <command>xdotool key --clearmodifiers End</command>
      </action>
    </keybind>
    <keybind key="S-BackSpace">
      <action name="Execute">
        <command>xdotool key --clearmodifiers Delete</command>
      </action>
    </keybind>
    <keybind key="W-F4">
      <action name="Execute">
        <command>xdotool key Caps_Lock</command>
      </action>
    </keybind>

Restart Openbox (Super-Space ==> Settings ==> Openbox ==> Restart) to put the changes into effect.

See the rc.xml file in this repository for the full, edited file (will also contain modifications for all other shortcuts mentioned in this guide).

Source: xdotool documentation (hosted on GitHub)

Shortcuts for maximize/unmaximize window (Windows-like shortcuts)

By default, CrunchBang includes aero-snap shortcuts for snapping windows to fill the left or right half of the screen, just like you can do in Windows. I also became dependent on shortcuts to maximize or unmaximize a window. This is a bit of a patchy solution that doesn't fully emulate Windows but it's good enough for me. Also, instead of Super-up and Super-down, we will use Super-Alt-Up and Super-Alt-Down.

To summarize, we will make the following shortcuts:

Maximize focused window: Super-Alt-Up
Unmaximize focused window: Super-Alt-Down

Steps:

Simply add the following code anywhere between the <keyboard> and </keyboard>:

    <keybind key="W-A-Up">
      <action name="Maximize"/>
    </keybind>
    <keybind key="W-A-Down">
      <action name="Unmaximize"/>
    </keybind>

Restart Openbox (Super-Space ==> Settings ==> Openbox ==> Restart) to put the changes into effect.

See the rc.xml file in this repository for the full, edited file (will also contain modifications for all other shortcuts mentioned in this guide).

Source: openbox.org wiki

Other shortcut customizations

Be default, using two finger scroll while the mouse is on the desktop will switch workspaces. While this is useful when using a mousewheel, I found it a bit too sensitive with a touchpad. So I disabled this by commenting out lines 766-771 of rc.xml

Specifically, the lines to comment out look like:

    <mousebind button="Up" action="Click">
      <action name="GoToDesktop"><to>previous</to></action>
    </mousebind>
    <mousebind button="Down" action="Click">
      <action name="GoToDesktop"><to>next</to></action>
    </mousebind>

See the rc.xml file in this repository for the full, edited file (will also contain modifications for all other shortcuts mentioned in this guide).

Upgrading the SSD drive

The androidcentral.com website has a detailed guide for upgrading the Acer C720 SSD. Note that this will void the warranty.

liangcj / AcerC720CrunchBang

CrunchBang Linux on the Acer C720 Chromebook

Putting Chromebook in developer mode

Enable booting from a USB drive

Installation

Getting the touchpad working

Improving the touchpad's performance

Fixing wireless, synaptic, and others

Fixing suspend

Sound keyboard shortcuts

Brightness keyboard shortcuts

Keyboard shortcuts for Page-Up, Page-Down, Home, End, Delete, Caps Lock

Shortcuts for maximize/unmaximize window (Windows-like shortcuts)

Other shortcut customizations

Upgrading the SSD drive

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