ASUS MeMO Pad 7 (asus-me176c)

Contributors

 * Minecrell
 * Mis012

Preparation
The device has a locked Android bootloader. To boot other operating systems, you need to replace the bootloader entirely with a custom one.


 * 1) Make sure that you are running Android 5.0 (Lollipop) - older versions did not have UEFI firmware.
 * 2) Install me176c-boot.
 * 3) Set up the   partition as additional ESP (EFI System Partition), see me176c-boot - Setting up an additional ESP partition.

Pre-built image
Download 2 files, as explained in installation.
 * 1)   (boot partition)
 * 2)   (rootfs)

Unpack them using.

pmbootstrap
Follow the pmbootstrap article to create your own postmarketOS image until you ran. Then use  to get the same files as in the pre-built images section.

Flashing boot partition
The bootloader cannot boot directly from a SD card, therefore the boot partition must be always on internal storage.

Boot into Fastboot mode, and use  (or   with pmbootstrap) to flash the boot partition. Then you need to create a boot entry for postmarketOS. Create a file :

title   postmarketOS volume  80868086-8086-8086-8086-000000000007 linux   /vmlinuz-edge initrd  /intel-ucode.img initrd  /initramfs options console=null
 * 1) Comment this out to get more output on screen while booting

Note: the filenames in  must match those in , else expect boot hang with   or similar console messages. In that case, inspect  directly or examine APD contents after flashing.

To install the new boot entry, boot into TWRP recovery, mount the ESP partition, and push the new configuration using ADB:

Now you can choose if you would like to install the root partition on internal storage or a SD card.

Internal Storage
Normally you should be also able to flash the rootfs using Fastboot:


 * System partition:
 * Data partition (larger):

However, if you get an error you may need to flash it using  via the TWRP recovery instead:

$ gzip -c ...-asus-me176c.img | adb shell "zcat | dd of=/dev/block/by-name/data bs=4m"

It looks like Fastboot can only handle small partitions on this tablet, so the error occurs whenever the image becomes too large for Fastboot to handle. Check via  (see also flash_fastboot_max_size). On a 16GB device the value is ~512MiB.

Note that on first boot the resizing of the partition containing the rootfs may fail quietly (or not occur at all?). Check the resulting filesystem(s) and partition(s) with  and. If necessary, boot to recovery, unmount the filesystem, and use  on the partition.

SD card
Write the root partition image to a partition on your SD card:


 * 1) Find the correct block device $ lsblk (usually   but sometimes  )
 * 2) Write the image to the partition (Warning: Existing data will be erased):
 * 3) Check resulting rootfs filesize   and use   to make better use of the partition.

ZRAM
Since the tablet has very little RAM, some applications might hang or crash easily. This affects web browsers (e.g. Firefox) in particular. Consider enabling ZRAM to improve the situation somewhat.

NOTE: On edge (but not v22.12) ZRAM is set up automatically. No changes are necessary.

Bluetooth
On recent Linux versions there seem to be problems with Bluetooth. It works only after some reboots or not at all, with randomly changing errors such as

[   9.600344] Bluetooth: hci0: BCM: features 0x0f [   9.601428] Bluetooth: hci0: BCM2076B1 [   9.601437] Bluetooth: hci0: BCM2076B1 (002.002.004) build 0000 [   9.602648] Bluetooth: hci0: BCM2076B1 'brcm/BCM2076B1.hcd' Patch [   9.659576] Bluetooth: hci0: Frame reassembly failed (-84) [  11.711297] Bluetooth: hci0: command 0xfc4c tx timeout [  19.967859] Bluetooth: hci0: BCM: Patch command fc4c failed (-110) [  19.967888] Bluetooth: hci0: BCM: Patch failed (-110) [  22.015081] Bluetooth: hci0: command 0xfc45 tx timeout [  30.206722] Bluetooth: hci0: BCM: failed to write clock (-110) [  32.255720] Bluetooth: hci0: command 0x0c03 tx timeout [  40.446793] Bluetooth: hci0: BCM: Reset failed (-110)

The cause for this regression is currently unknown. It seems like Linux receives garbage data from the Bluetooth chip. :(

result
Some users have reported being able to charge the device and connect a USB-Hub using a Micro USB OTG Y-cable like this one. It is a cable with an integrated resistor, which manages the splitting. This enables using the tablet with a keyboard, mouse, mass-storage-device,and whatever you can think of using USB. The USB protocol is. (The CPU also supports  but the interface is sadly not exposed.)

Phosh tweaks / gotchas

 * Unlock button is not accessible for lockscreen rewake in landscape mode with large display scales (150%, 175%). Power cycle seems to be required.
 * Auto-rotate lockscreen orientation is fixed at locking.

PHOSH
...WIP...

SXMO
Thanx to it's minimalistic approach SXMO works pretty well on the me176c. It requires some practice to use it so read the docs :) !

But... this does not resolve memory-hungry issues like internet browsing with firefox or chromium. You have to be kind with the hardware:  can't do much UI-/visual-stuff !

As of  there is no device profile. Here is where the work is needed to have a user-friendly SXMO on me176c(x). This is how the  of the   looks like

and for the Xiaomi Poco F1 (xiaomi-beryllium):

All other device profiles are under the same directory.

Another very important  is: