Difference between revisions of "Google Nexus 7 2012 (asus-grouper)"

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(update grouper / tilapia according to MR 1025)
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=== Special installation process (development setup, kernel over approx. 4M) ===
=== [NOT WORKING ANYMORE 05/03/2019 ] 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:
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:

Revision as of 19:15, 5 March 2020

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

1 $ pmbootstrap init # choose asus grouper or asus tilapia
2 $ pmbootstrap install
3 $ pmbootstrap flasher flash_kernel

[NOT WORKING ANYMORE 05/03/2019 ] 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 https://gitlab.com/alpine-mobile/pmbootstrap.git
 4 cd pmbootstrap
 5 alias pmbootstrap=~/code/pmbootstrap/pmbootstrap.py
 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 https://github.com/okias/linux.git
17 cd linux
18 source ~/code/pmbootstrap/helpers/envkernel.sh
20 sudo curl -o .output/.config https://gitlab.com/alpine-mobile/pmaports/raw/master/device/linux-asus-grouper/config-asus-grouper.armv7
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-asus-nexus7-grouper.dtb > ~/code/linux/.zImage-dtb # grouper or tilapia
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

NOTE: If you plan flash Android, this may change size of your data partition. You can fix it by resizing partition in TWRP before flashing Android.

You should proceed very carefully here.

Prerequisites: Official TWRP, at least version 3.3.1-0, binaries are here for grouper or tilapia.

ensure you already run

1 pmbootstrap export

and then proceed with

1 # start TWRP
2 (computer) $ adb shell
3 (twrp) $ df # look for the data partition. should be something like /dev/block/mmcblk0p9 or p10 with /data next to it
4 (twrp) $ umount /dev/block/mmcblk0p__ <- fill partition number
5 (twrp) $ umount /dev/block/mmcblk0p__ <- fill partition number # again, it can be mounted as /sdcard and as /data
6 (computer again) $ adb push /tmp/postmarketOS-export/asus-grouper.img /dev/block/mmcblk0p__ <- fill partition number
  • grouper has likely data on /dev/block/mmcblk0p9 but make sure!
  • tilapia has likely data on /dev/block/mmcblk0p10 but make sure!

it's probably because tilapia has additional modem partition. If you're not sure, come to our Matrix channel and ask :)

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 NFC wired, not tested yet. Please update if it'll work for you.
GPS Needs entry in DeviceTree. Not tried yet.
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.
Y Charger there is driver SMB347 for the charger in upstream kernel, but it doesn't have support for device-tree. Patches for upstreaming: https://github.com/okias/linux/commits/smb3xx-charger
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

  • 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 https://wiki.postmarketos.org/wiki/XFCE4 for adjustments.
  • Weston (on legacy): Boots on legacy kernel. Touchscreen is working.

Development Notes


  • Up-to-date kernel, where tegra development ongoing.
  • Old Android kernels: LineageOS kernel sources Unlegacy kernel sources
  • Ubuntu Nexus 7 Kernel wiki (old, last updated 2012)
  • 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], or can be 4.18 can be grabbed from the factory images for KitKat


  • The touchscreen input device is named elan-touchscreen.
  • (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 fbdev-backend.so uses pixman-type=3 (PIXMAN_TYPE_ABGR), which now does not require configuration.


  • 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.
  • To connect follow the instructions on this page.
  • (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.

Pending Issues

Fun Fact

grouper was the first tablet to run postmarketOS!

See also

- dmesg logs from various tegra devices https://paste.sr.ht/%7Eokias