torstai 12. huhtikuuta 2018

Gemini PDA hacker's guide

 Gemini PDA hacker's guide

Here's a collection of hints on how to do stuff on your Gemini they don't tell in the official documentation.

Linux warning

 Just a warning for non-hacker users: The Debian Linux for Gemini is still early alpha (12. Apr 2018) and it's not usable for daily work yet. Xorg uses slow software rendering, keyboard mapping is not right, Fn-modifier doesn't work so you can't type some characters etc. The best way to use it is from another computer via SSH.  This is why it's called technology preview.

Anyway, make sure you have everything backed up and ready to reflash everything if something breaks.

Flashing the operating system

There is now official Linux version of the flasher tool provided by Planet. Use it.

Accessing Linux via USB networking

If you are in situation when you can't access Linux side of Gemini, you can get there by USB networking:
  1. Boot to Linux on Gemini
  2. Connect USB cable
  3. ssh gemini@
 This works directly on Ubuntu.

If DHCP doesn't work, you can do sudo ip addr add dev usb0; sudo ip link set usb0 up
(usb0 can be renamed into something else by udev, check dmesg)

Linux setup and general hints

I've created a shell script to help setting up Gemini's Debian:

Usage is documented in the script itself, please read it.

  • GDM display manager from Gnome doesn't seem to work. Gray screen after logging in. Use the default display manager.
  • In Gnome the WiFi password dialog doesn't seem to work from top right corner menu. Open Settings / Network from menu, from there you can connect.
  • By default Debian uses connman for managing network connections. You might want to remove it and install NetworkManager which is more commonly used by desktops. 
  • Don't try to mount the android system partition from Linux, at least in rw  mode. Android won't boot after that and you'll need to reflash.
  • To get larger widgets for touch usage in Gnome run:
    gsettings set org.gnome.desktop.interface scaling-factor 2 

Booting TWRP

It's possible to boot TWRP to install other distributions such as Sailfish on the Gemini. But booting it can be tricky. TWRP for Gemini can be found here.

  1. Copy the files you want to flash with TWRP to Android Download folder, sd card or other place accessible from TRWP.
  2. Boot to Debian.
  3. Copy the TWRP .img file to Gemini from your pc:
    1. scp twrp-geminipda-3.2.1-0.img gemini@
  4. sudo dd if=twrp-geminipda-3.2.1-0.img of=/dev/disk/by-partlabel/recovery
  5. Power off the device.
  6. Power on the device by holding ESC for until screen turns on. TWRP should launch.
NOTE: Next time you boot Android, the recovery partition will be wiped and you need to repeat this!

Installing Sailfish

It's now in "closed beta". Don't ask me where to download it from. Hopefully it will be public soon. Here are the steps to install it in it's current form:

  1. Install Android + Linux image, set up Debian (at least run resize2fs if you don't run the full script)
  2. Make a backup of linux_boot: sudo dd of=linux-boot.img if=/dev/disk/by-partlabel/linux_boot
  3. Download the sailfish .zip file to Android's Download directory. For some reason TWRP didn't find it if i just copied it to Android filesystem via Debian. MicroSD card should also work.
  4. Boot TWRP.
  5. Select the .zip from Downloads and install.
  6. Power off and boot to Linux. Sailfish should start. The tutorial is a bit broken but you should get past it.
  7. In Sailfish make a backup of linux_boot: dd of=sailfish-boot.img if=/dev/disk/by-partlabel/linux_boot

Switching between Sailfish and Debian

Overwrite the linux_boot partition with image you made earlier. For example to get from Sailfish to Debian, use dd if=linux-boot.img of=/dev/disk/by-partlabel/linux_boot

GUI for this would be nice.

NOTE: You can access Sailfish sysroot from Debian at /.stowaways/sailfishos and Linux sysroot from Sailfish by mounting /dev/mmcblk0p29 in any directory.

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