install guixsd on asus c302

code
tool

2018-08-12

2021-03-23

laptop

intro

I recently acquired the Asus Chromebook Flip C302 (hereinafter "c302"), and this page outlines the steps I took to get GuixSD (hereinafter "guix") running smoothly on it. The process was pretty straightforward, but the occasional tweaking convinced me that having the details written down would be useful.

The gist of what I'm doing here is to replace the preinstalled ChromeOS (hereinafter "cros") with guix.

Of course, the reasons for doing this may not be obvious. For one, the process outlined in this page will void the warranty. Also, there is the possibility of bricking the device during such a procedure, so, if you plan on using the information here as any kind of advice, please do so and operate on your machine at your own risk!

Note: With the exception of native audio, hibernation, and auto-tablet-mode, everything does work reasonably well.

alternatives

Instead of a complete guix overhaul, another worthy option may be to keep the original cros and to dual boot it with guix. This requires the so-called RW_LEGACY firmware which keeps the secure cros boot payload intact.

Benefits of the dual boot option are that full hardware functionality would be easily accessible via cros, and screws need not be ~~screwed~~ messed around with. The downside, however, is that precious disk space must be allotted to cros, and a brief confirmation screen persists at bootup.

inputs

Before commencing with the firmware-flashing and keyboard-bashing, I had a few days to research the whole process and gather a reference base. Here are some must-reads (as of August 2018):

And these are the hardware needed to make it all happen:

c302 laptop
external storage devices of at least 8 gb each (eg. USB flash drives)
- one for cros backup
- (another or reuse above) for guix install image
- (another or reuse above) for ROM firmware backup
USB network adapter
USB type-c adapter
- only if necessary, since c302 has USB of type-c only

1. backup & prep

Boot into cros.
Redeem any benefits (like Google Drive storage space) that come with the chromebook purchase.

enable developer mode

Do a three-finger-salute using esc + f3 + power (f3 is the fourth, refresh button at the top; power is on the left side of the machine).
Wait for the machine to boot into a bright confirmation screen. Press ctrl + d ("d" for "developer"). Wait more for the machine to boot back into cros.

guix installer

Create the guix installation medium (perhaps using another system with a rich shell).
1. Download and verify installation image.
2. ```
xz -d guixsd-install-{VER}-{SYS}.iso.xz
```
3. ```
dd if={IMAGE}.iso of=/dev/{MEDIUM}
```

backup cros

Get the Chromebook Recovery Utility from the Web Store.
Run the utility, plug in an external drive, and create the recovery medium. Wait for this to finish.

2. goodbye ChromeOS

flash with UEFI coreboot

Power off, and open up the laptop at the bottom.
- Requires: a torx t4 screw driver, a small Phillips screw driver, and (preferably) a small plastic wedge.
- The two rubber feet beside the hinges each conceal an additional screw.
- The bottom plate will have to come off. (Tip: The plate has slight cut-outs around each of the ports on the sides, which the wedge can get between.)
Remove the write-protect screw.
- The orange-outlined and "WP"-annotated screw is concealed by a black tape near the center.
Without fully reassembling the bottom plate, carefully boot into cros and open up a terminal.
Follow MrChromebox's instructions and use his fabulous script to install the "Full ROM Firmware". Wait for this to finish.
- During this step, the original firmware can be backed up to an external drive. (Tip: For maximum device reuse, perform this backup first and move the .rom file to a safe location before using the same external storage device to backup cros or to generate a guix installer.)
- A second execution of the same script, after a boot, may be required to complete the firmware install.
Reinstate the write-protect screw, and close up the bottom plate.

3. hello GuixSD

Note: The steps herein will probably populate the kernel with non-free binary blobs. The Guix community does not support such use of the system or the promotion thereof.

Boot into the guix installation medium.
- If the medium does not boot, frantically press some keys at the beginning of the bootup sequence to access the coreboot menu, and then select the .efi file somewhere in "Boot From File".
Start following the guix installation manual.
- Use GPT partitioning and make sure to create an ESD partition.
- Connect to the internet.

configure kernel & guix system

See my guix system configuration as an example: c.scm

Set to install a customised vanilla kernel.
- Use the default vanilla configuration (or start streamlining right here, right now! See "more" section below).
- But modularise all of guix's default initrd modules in order for guix to boot properly.
  - See (define* (default-initrd-modules ...)) in the above link.
- Also modularise any components that will need to load non-free firmware.
- Set guix to recognise the resulting kernel configuration file.
- Test the kernel configuration separately with
```
guix environment linux-libre --ad-hoc ncurses -- make nconfig
```
Set to install linux-firmware. It includes the iwlwifi microcode for native wireless support.
Set the (initrd-modules ...) expression in (operating-system ...) to include "mmc_block" and "sdhci-pci".
Set a proper networking package (eg. network-manager, connman, wicd, wpa-supplicant, etc. Don't wanna be stuck with an installation that can't get online, hence not easily reconfigurable, hence pretty useless).

guix system init /.../{SYSCFG}.scm /.../{TARGET}

Reboot and start hacking!

laptop

4. more

Note: The kernel configuration tips below have not been advised by any official sources. They are my guesses and opinions in relation to desired functionality.

Please look inside the kernel configuration file linked below for the relevant kernel version.

My guix system configuration: c.scm

minimal kernel

Compile in only the necessary drivers
- See my kernel configuration: c.kconfig
- Take note of various Intel Skylake-, Asus-, and Chromebook-specific options.
- As in the "configure ..." section above, keep guix's default initrd modules as modules. Also modularise those components for which you need non-free firmware.
  - ```
  grep '=m' c.kconfig
```

power

cpu freq: Good.
- The "ondemand" cpufreq policy governor seems to work fine. The frequency idles at 600 MHz and shoots up to max on demand, as advertised.
suspend to RAM: Works partially.
- ```
# echo mem >/sys/power/state
```
- For reliable suspend to RAM, do not compile the skylake audio drivers (see "audio" below). Doing so floods dmesg after a second resume.
suspend to disk: NEEDS TESTING
Using acpid: NEEDS TESTING

-> Power management and ACPI options
  -> CPU Frequency scaling
    -> Default CPUFreq governor
    -> 'ondemand' cpufreq policy governor

  -> Suspend to RAM and standby
  -> Hibernation (aka 'suspend to disk')
  -> Opportunistic sleep
  -> User space wakeup sources interface
  -> ACPI ... Support

audio

native audio: NOT OPERATIONAL
- Per GalliumOS issue 379, I've attempted at enabling audio on c302, but to no avail. Loading a user-uploaded firmware produces no discernible effect, except extreme heat :-(.
USB audio: Should work, according to comments online.

-> Device Drivers
  -> Sound card support
    -> Advanced Linux Sound Architecture
      -> ALSA for SoC audio support
        -> Intel ASoC SST drivers
        -> SKL/BXT/KBL/GLK/CNL... Platforms
        -> Intel Machine drivers
          -> SKL with NAU88L25 and SSM4567 in I2S Mode
          -> SKL with NAU88L25 and MAX98357A in I2S Mode

      -> USB sound devices
        -> USB Audio/MIDI driver

display

graphics: Good.
- Set the xorg driver to be "intel".
- In the "configure ..." section above, the linux-firmware package brings in the necessary Intel graphics firmware (i915/skl_dmc_ver1*.bin).
webcam: Good.
tablet mode: NEEDS TESTING

-> Device Drivers
  -> Graphics support
    -> /dev/agpgart (AGP Support)
      -> Intel 440LX/BX/GX, I8xx and E7x05 chipset support
    M -> Intel 8xx/9xx/G3x/G4x/HD Graphics

  -> Multimedia support
    -> Cameras/video grabbers support
    -> V4L platform devices
      -> SoC camera support

input

keyboard: Good.
- Set the xkb model to be "chromebook", via either the "XkbModel" option for xorg, or setxkbmap -model chromebook.
touchpad: Good.
- The native Elan touchpad makes good use of xf86-input-cmt.
- Create custom "cmt" packages, for the system to recognise and for xorg to load.
  - See my-libevdevc, my-libgestures, and my-cmt package definitions in c.scm linked above.
- The sensitivity may be too high by default. Play around with the xorg options, taking special note of the "AccelerationProfile", "Pointer/Scroll Sensitivity", and "Scroll Y Out Scale". See xinput list-props {DEVID} for more options.
touchscreen: Good.

-> Device Drivers
  -> Input device support
    -> Keyboards
      -> AT keyboard

    -> Mouse interface
    -> Mice
      -> ELAN I2C Touchpad support
      -> Enable I2C support

    -> Touchscreens
      -> Elan eKTH I2C touchscreen

networking

bluetooth: Should work, according to comments online.
- In the "configure ..." section above, the linux-firmware package brings in the necessary ibt firmware (intel/ibt-hw-37.8.*.bseq).
wifi: Good.
- In the "configure ..." section above, the linux-firmware package brings in the necessary iwlwifi firmware (iwlwifi-7265*.ucode).

-> Networking support
  -> Bluetooth subsystem support
    -> Bluetooth Classic (BR/EDR) features
    -> RFCOMM protocol support
    -> HIDP protocol support
    -> Bluetooth device drivers
    M -> HCI USB driver
    M -> HCI UART driver
      -> Intel protocol support
                
  -> Wireless
    -> cfg80211 - wireless configuration API
    -> Generic IEEE 802.11 Networking Stack (mac80211)
                
 Device Drivers
  -> HID support
    -> User-space I/O driver support for HID subsystem
                
  -> Network device support
    -> Wireless LAN
      -> Intel devices
    M -> Intel Wireless WiFi Next Gen AGN ...
      -> Intel Wireless WiFi MVM Firmware support

sd

MicroSD: Good.

-> Device Drivers
  -> MMC/SD/SDIO card support
    -> Secure Digital Host Controller Interface support
    -> SDHCI support on PCI bus

misc

wayland: NEEDS TESTING
desktop: See my dotfiles for an example of how to rock an xorg + window-manager-based desktop.