Google Nexus 7 2012 (asus-grouper)

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Revision as of 18:03, 19 January 2020 by Gull Code (talk | contribs) (→‎UI options: Added XFCE4 since I can confirm it works)
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Google (ASUS) Nexus 7 (2012)
Google Nexus 7
Google Nexus 7
Manufacturer Google (ASUS)
Name Nexus 7 (2012)
Codename asus-grouper & asus-tilapia
Released 2012
Category testing
Original software Android 4.1.2 on Linux 3.0
Chipset Nvidia Tegra 3
CPU Quad-core 1.2 GHz Cortex-A9
Display 800x1280 IPS
Storage 8/16/32 GB
Memory 1 GB
Architecture armv7
USB Networking
3D Acceleration
Mobile data


  • okias


  • antonok
  • pangelo

Users owning this device

  • 00p513 (Notes: Have new one!)
  • Antonok
  • Blitztide
  • BogdanTheGeek (Notes: E1565 no GSM)
  • Clamor (Notes: Unlegacy Android Project M ROM)
  • Eloy
  • Gull Code (Notes: OK,daily use with XFCE4)
  • Hilledkinged (Notes: Revived from corrupt bootloader)
  • Isot42 (Notes: OK PM269 version)
  • Maff (Notes: Multiple)
  • Nergzd723 (Notes: emmc dead, bct partition intact, possible to fusee-gelee)
  • Okias (Notes: OK, HW rev.E1565 (asus-tilapia))
  • Pangelo (Notes: original grouper (non-GSM) model)
  • Pojntfx
  • The Arjdroid (Notes: Impressive! Works with phosh & xfce4, but not daily driveable yet. It needs 3D acceleration for smoother UI, & firefox fix crashes. Great for running it as a no display server like a raspberry pi. Running with xfce4 can make it usable as a smart display like a calendar or something.)
  • Unah (Notes: grouper E1565 variant)


How to enter flash mode

  • Connect a USB cable
  • Power the device off
  • Hold power + volume down
  • fastboot should work when the green android appears on the screen

Installation process (legacy kernel)

1 $ git clone
2 $ cd pmbootstrap
3 $ ./ init
4 $ ./ install
5 $ ./ flasher flash_kernel

Instalation process (mainline kernel)

Not merged into pmOS yet, so if you want mainline use this repository for now.

1 $ git clone
2 $ cd pmbootstrap
3 $ ./ init
4 $ ./ install
5 $ ./ flasher flash_kernel

Special installation process (development setup, kernel over approx. 4M)

If you need bigger kernel, this includes way to the latest mainline kernel with size limited only by BOOT partition or how much device will be able boot it:

 1 mkdir ~/code
 2 cd ~/code
 3 git clone
 4 cd pmbootstrap
 5 alias pmbootstrap=~/code/pmbootstrap/
 6 pmbootstrap init
 7 # pmbootstrap initfs hook_add debug-shell # not required, only for debugging
 8 pmbootstrap export
 9 pmbootstrap chroot -- apk add abootimg android-tools mkbootimg dtbtool findutils
10 export DEVICE="$(pmbootstrap config device)"
11 export WORK="$(pmbootstrap config work)"
12 export TEMP="$WORK/chroot_native/tmp/mainline/"
13 mkdir -p "$TEMP"
15 cd ~/code
16 git clone
17 cd linux
18 source ~/code/pmbootstrap/helpers/
20 sudo curl -o .output/.config
21 sudo sed -i "s|CONFIG_INITRAMFS_SOURCE=\"\"|CONFIG_INITRAMFS_SOURCE=\"initfs-extracted\"|" .output/.config
22 pmbootstrap initfs extract # ugly hack to get kernel booting without external initrd
23 sudo cp -r ~/.local/var/pmbootstrap/chroot_rootfs_asus-grouper/tmp/initfs-extracted ./.output/ # initfs is later compiled into kernel
25 make -j5
27 cd ~/code/linux/.output/arch/arm/boot
28 cat zImage dts/tegra30-grouper-bach.dtb > ~/code/linux/.zImage-dtb
29 cp ~/code/linux/.zImage-dtb "$TEMP"/zImage-dtb
31 pmbootstrap flasher list_devices
a. Boot only
1 pmbootstrap chroot -- fastboot boot /tmp/mainline/zImage-dtb
b. Flash kernel:

We're still not able bundle classic boot.img, so we need generate boot.img without ramdisk (which is already included inside kernel).

1 pmbootstrap chroot -- mkbootimg-osm0sis --kernel "/tmp/mainline/zImage-dtb" --base "0x10000000" --kernel_offset "0x00008000" --ramdisk_offset "0x01000000" --tags_offset "0x00000100" --pagesize "2048" -o "/tmp/mainline/boot.img"
2 pmbootstrap chroot -- fastboot boot /tmp/mainline/boot.img # test if image will boot
3 pmbootstrap chroot -- fastboot flash boot /tmp/mainline/boot.img # flash only tested image

Flashing rootfs

rootfs under 650MB

1 pmbootstrap flasher flash_rootfs

rootfs over 650MB to USERDATA

Be very careful here and feel free to ask on Matrix channel before accidentally bricking your device with selecting bad partition! THIS MAY SHRINK YOUR DATA PARTITION IF YOU INSTALL ANDROID AGAIN! YOU MAY HAVE TO RESIZE IN TWRP!

Prerequisites: Official TWRP, at least version 3.3.1-0 for

if you haven't done export yet, do

1 pmbootstrap export
1 # start TWRP
2 (computer) $ adb shell
3 (twrp) $ df #look for the data partition. should be something like /dev/block/mmcblk0p10 with /data next to it
4 (computer again) $ adb push /tmp/postmarketOS-export/asus-grouper.img /dev/block/''_REPLACE_WITH_CORRECT_PARTITION_''
  • grouper has most likely data on mmcblk0p9 but VERIFY!
  • tilapia has most likely data on mmcblk0p10 but VERIFY!

Hardware status (mainline)

There is multiple hardware revisions, so this status may not apply to all of them. This status apply for tilapia (Bach revision).

Status Hardware Info
Y Booting ... but when is kernel larger than approx 4MB, initfs must be packed directly inside kernel (not into boot.img as usual), otherwise kernel won't boot. With downstream kernel it works.
Y Touchscreen Works.
Y USB Works.
Y SDHCI Works.
Y WiFi Wi-Fi works (best with IWD daemon: apk add iwd; rc-config del wpa_supplicant; rc-config add iwd; and HOWTO).
Y GPIO keys There is 3 keys on GPIO: Power, Volume up, Volume down.
Y Battery Driver works.
P Charger there is driver for the charger in upstream kernel, but it doesn't have support for device-tree
Y Bluetooth Works well, it has even BT 4.0, also BT 5.0 headphones works.
Y Sound sound also works, but require ALSA UCM configuration (for now you'll need to enable DACs and etc using alsamixer)

alsamixer -c 0 # and enable something like: "Speaker R" "Speaker L" "DAC MIXR INF1" "DAC MIXL INF1" "SPOL MIX DAC R1" "SPOL MIX DAC L1" "Stereo DAC MIXR DAC R1" "Stereo DAC MIXL DAC L1"

Y Temperature sensor temperature sensor works
Y Proximity sensor
Y Light sensor Driver al3010. Brightness regulation works, install iio-sensor-proxy . It's slightly oversensitive.
N Front camera
P 3D support See Nvidia_Tegra_2_(tegra20)#Graphics
N Modem Present only on tilapia, no-one plan to work on it for now.

UI options

  • Weston: Boots on legacy kernel. Touchscreen is working on legacy kernel. The reboot issue exists on legacy kernel. Maybe it is an issue with the kernel we are using?
  • Phosh (mainline only): Purism Librem 5 compositor and GNOME based environment, needs performance optimization, but works.
  • Xfce4 (mainline only): Xfce4 is a GTK-based desktop environment aiming to be fast and lightweight. Needs performance optimization, but works. Follow the guide at for adjustments.

Development Notes


  • The default images for android provided by google have the bootloader broken, meaning it can't be flashed. It does not seem to affect the install process of PostMarketOS, but is something to take into account. If you need a working bootloader image version 4.23 can be found [here]


  • (legacy) CONFIG_VT had to be enabled for graphics to work. In menuconfig this is located under Device Drivers -> Character devices -> Virtual terminal.
  • (legacy) /sys/class/graphics/fb0/mode is empty on boot, it must have U:800x1280p-0. This uses the same initfs hook as many other devices. Update: Seems to be correctly set now
  • (legacy) weston with uses pixman-type=3 (PIXMAN_TYPE_ABGR), which now does not require configuration.
  • The touchscreen input device is named elan-touchscreen.


  • There's a proper firmware subpackage now, wifi device should work out-of-the box.
  • "Desktop" Linux firmware are outdated. Check here for latest one.
  • (legacy)It is possible to manually get wifi working by manually copying fw_bcmdhd.bin and nvram.txt to their kernel-specified locations and configuring /etc/network/interfaces. At this point, running /etc/init.d/networking restart, gave an error about being unable to get a MAC address. After restarting the device to find that wifi Just Worked™, it was possible to successfully scan for wireless networks and establish a connection to secured wireless APs.
  • To connect follow the instructions on this page.

Pending Issues

  • pmaports#201: device seems to reboot spontaneously under heavy load (could be a hardware problem though, needs more testing). UPDATE:22/12/19 - Seems to noly happen with "legacy" kernel.
  • pmbootstrap#1422: The system partition is too small to hold rootfs images over 650Mb (e.g. Plasma Mobile is about 1.1Gb). Flashing to userdata partition fails.
  • pmbootstrap#1844: grouper: move to grate (upstream close) kernel

See also

These are other pending issues that are related to this device:

  • pmbootstrap#60: Use the system and userdata partition on Android with LVM

Fun Fact

grouper was the first tablet to run pmOS!

tilapia has exactly same HW as grouper