Ubuntu installation guide ( New method )

Another installation guide for newer Ubuntu port.

This document is a guide for installing Ubuntu Linux on your Xiaomi Mi Pad 5 with the latest mainline kernel.

PLEASE READ SLOWLY AND CAREFULLY!! BE SURE TO UNDERSTAND THE ENTIRE GUIDE BEFORE STARTING!!

Don’t run all commands at once and don’t rerun the commands if you interrupt the process. You need to be familiar with command line interfaces beforehand and you must not commit any typo with any commands. You may permanently break your device!

Fork the repository

This repository is currently maintained by map220v on GitHub:

GitHub - map220v/ubuntu-xiaomi-nabuGitHub

Open your browser and search GitHub, then login your account, click the link above.

A screenshot showing map220v's GitHub repository.

Click the "Fork" button to fork this repository. Once it forked, head to the next part of this guide, we'll build a custom system image for our further installation.

Build system image

Thanks to GitHub Actions, the build sections are all finished automatically, so we don't need to compile them manually. After you forked this repository, go to "Actions" tab, find the "rootfs" section in sidebar, then click "Run workflow" to build a kernel and system image. It will takes you about 23 minutes and 42 seconds to finish this build.

The Actions sections showing in my forked repository.

Once the build process is finished, click the "rootfs" in your workflow table. Scrolling down the page, you'll find the "Artifacts" section.

Here are your build files, download the xiaomi-nabu-debs_6.7-working and rootfs package. Either rootfs_lomiri_6.7-working or rootfs_ubuntu-desktop_6.7-working is OK.

WARNING: DO NOT download 6.8 packages as 6.8 kernel is known to have a broken screen framebuffer, it will show nothing on screen (even the console) after you installed them.

From now on, follow the old installation guide until the "Install new system" chapter.

Partition the UFS

This procedure will not erase your Android data files, since Android will automatically fixing the userdata partition.

To modify the partitions on the UFS, we'll need to download a 3rd-party recovery environment called "Orangefox Recovery" Link is here below:

xiaomi-nabu-orangefox.imgGoogle Docs

Once you've downloaded, open a terminal and type the following commands:

adb reboot bootloader
fastboot boot /path/to/recovery.img 

This will start booting recovery image. Once the screen is on, use the terminal to continue processing. We well use adb shell command to finish the rest of this guide. Enter this command in your terminal, it well help you to check the userdata partition's location:

ls -l /dev/block/bootdevice/by-name/ | grep userdata
lrwxrwxrwx 1 root root 16 1971-06-22 05:04 userdata -> /dev/block/sda31    #Example output will like this.

In this example, the userdata partition is located in the 31st partition of the whole disk. It has the biggest size, compared with other partitions. So this is the key for requiring new space for our Ubuntu installation.

To resize the userdata partition, we'll need to use the parted command tools to do this. Now let's open adb shell again and start typing parted in the terminal.

parted /dev/block/sda
GNU Parted 3.3
Using /dev/block/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted)

Enter print command to list all partitions for /dev/block/sda :

If you are using newer recovery like TWRP or PBRP Recovery, you need to download parted and use adb command to copy it to internal storage. Run these commands to finish this:

adb push parted /tmp/
adb shell chmod 755 /tmp/parted
adb shell

Then you will see your current partition table with userdata being the last partition Below is an example of output:

(parted) print
print
Model: SAMSUNG KLUDG4UHDC-B0E1 (scsi)
Disk /dev/block/sda: 126GB
Sector size (logical/physical): 4096B/4096B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name             Flags
 1      24.6kB  32.8kB  8192B                switch
 2      32.8kB  65.5kB  32.8kB               ssd
 3      65.5kB  98.3kB  32.8kB               dbg
 4      98.3kB  131kB   32.8kB               bk01
 5      131kB   262kB   131kB                bk02
 6      262kB   524kB   262kB                bk03
 7      524kB   1049kB  524kB                bk04
 8      1049kB  1573kB  524kB                keystore
 9      1573kB  2097kB  524kB                frp
10      2097kB  4194kB  2097kB               countrycode
11      4194kB  8389kB  4194kB               misc
12      8389kB  12.6MB  4194kB               vm-data
13      12.6MB  16.8MB  4194kB               bk06
14      16.8MB  25.2MB  8389kB               logfs
15      25.2MB  33.6MB  8389kB               ffu
16      33.6MB  50.3MB  16.8MB               oops
17      50.3MB  67.1MB  16.8MB               devinfo
18      67.1MB  83.9MB  16.8MB               oem_misc1
19      83.9MB  101MB   16.8MB  ext4         metadata
20      101MB   134MB   32.9MB               bk08
21      134MB   168MB   34.2MB               splash
22      168MB   201MB   33.6MB               bk09
23      201MB   9328MB  9127MB               super
24      9328MB  9328MB  131kB                vbmeta_system_a
25      9328MB  9328MB  131kB                vbmeta_system_b
26      9328MB  9396MB  67.1MB               logdump
27      9396MB  9530MB  134MB                minidump
28      9530MB  9664MB  134MB                rawdump
29      9664MB  10.7GB  1074MB  ext4         cust
30      10.7GB  10.9GB  134MB   ext4         rescue
31      10.9GB  126GB   115GB                userdata

Now let’s continue partitioning: Here the size of userdata can be decided by yourself.

Delete partition 31 and again make sure it is not deleted incorrectly.

(parted) rm 31
rm 31

126GB is the End value for the new userdata partition. Since the starting point for userdata is 10.9GB, the new size would be 126G - 10.9G = 115G.

Check the results:

(parted) print
print
Model: SAMSUNG KLUDG4UHDC-B0E1 (scsi)
Disk /dev/block/sda: 126GB
Sector size (logical/physical): 4096B/4096B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name             Flags
 1      24.6kB  32.8kB  8192B                switch
 2      32.8kB  65.5kB  32.8kB               ssd
 3      65.5kB  98.3kB  32.8kB               dbg
 4      98.3kB  131kB   32.8kB               bk01
 5      131kB   262kB   131kB                bk02
 6      262kB   524kB   262kB                bk03
 7      524kB   1049kB  524kB                bk04
 8      1049kB  1573kB  524kB                keystore
 9      1573kB  2097kB  524kB                frp
10      2097kB  4194kB  2097kB               countrycode
11      4194kB  8389kB  4194kB               misc
12      8389kB  12.6MB  4194kB               vm-data
13      12.6MB  16.8MB  4194kB               bk06
14      16.8MB  25.2MB  8389kB               logfs
15      25.2MB  33.6MB  8389kB               ffu
16      33.6MB  50.3MB  16.8MB               oops
17      50.3MB  67.1MB  16.8MB               devinfo
18      67.1MB  83.9MB  16.8MB               oem_misc1
19      83.9MB  101MB   16.8MB  ext4         metadata
20      101MB   134MB   32.9MB               bk08
21      134MB   168MB   34.2MB               splash
22      168MB   201MB   33.6MB               bk09
23      201MB   9328MB  9127MB               super
24      9328MB  9328MB  131kB                vbmeta_system_a
25      9328MB  9328MB  131kB                vbmeta_system_b
26      9328MB  9396MB  67.1MB               logdump
27      9396MB  9530MB  134MB                minidump
28      9530MB  9664MB  134MB                rawdump
29      9664MB  10.7GB  1074MB  ext4         cust
30      10.7GB  10.9GB  134MB   ext4         rescue

Note the end of the last partition in the above list, 10.9GB, this number will be used as the start of the new userdata partition, followed by the end of the partition. Let say that we want to make an approx 40GB userdata partition using the following command:

(parted) mkpart userdata   10.9GB 50GB
mkpart userdata   10.9GB 50GB    #If you added "ext4" behind the "userdata" text, your data will be erased when you reboot. 

Between userdata and 10.9GB are 3 spaces, one of them replace the partition type flag, it is important to use 3 spaces at this step.

Run print again to see the results.

(parted) print
print
Model: SAMSUNG KLUDG4UHDC-B0E1 (scsi)
Disk /dev/block/sda: 126GB
Sector size (logical/physical): 4096B/4096B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name             Flags
 1      24.6kB  32.8kB  8192B                switch
 2      32.8kB  65.5kB  32.8kB               ssd
 3      65.5kB  98.3kB  32.8kB               dbg
 4      98.3kB  131kB   32.8kB               bk01
 5      131kB   262kB   131kB                bk02
 6      262kB   524kB   262kB                bk03
 7      524kB   1049kB  524kB                bk04
 8      1049kB  1573kB  524kB                keystore
 9      1573kB  2097kB  524kB                frp
10      2097kB  4194kB  2097kB               countrycode
11      4194kB  8389kB  4194kB               misc
12      8389kB  12.6MB  4194kB               vm-data
13      12.6MB  16.8MB  4194kB               bk06
14      16.8MB  25.2MB  8389kB               logfs
15      25.2MB  33.6MB  8389kB               ffu
16      33.6MB  50.3MB  16.8MB               oops
17      50.3MB  67.1MB  16.8MB               devinfo
18      67.1MB  83.9MB  16.8MB               oem_misc1
19      83.9MB  101MB   16.8MB  ext4         metadata
20      101MB   134MB   32.9MB               bk08
21      134MB   168MB   34.2MB               splash
22      168MB   201MB   33.6MB               bk09
23      201MB   9328MB  9127MB               super
24      9328MB  9328MB  131kB                vbmeta_system_a
25      9328MB  9328MB  131kB                vbmeta_system_b
26      9328MB  9396MB  67.1MB               logdump
27      9396MB  9530MB  134MB                minidump
28      9530MB  9664MB  134MB                rawdump
29      9664MB  10.7GB  1074MB  ext4         cust
30      10.7GB  10.9GB  134MB   ext4         rescue
31      10.9GB  50.0GB  39.1GB               userdata

Exit the parted tool finally.

Now userdata resizing is done. Restart your tablet to apply changes.

Here comes a fun thing:

Android stores your data inside the userdata partition. When you reset your Android device to its factory default settings, your data will be erased. This is because factory reset is equal to format the userdata partition using ext4 filesystem. However, if you delete the userdata partition and recreate it without formating, your data will be saved after a reboot. Probably because Android can fix this problem automatically.

If you added "ext4" behind the "userdata" text, your data will be erased when you reboot. 

Assign new EFI partition

Follow this chapter to assign EFI partition.

Install new system

Enter fastboot mode and repeat the previous steps.

We'll use the free space for our Ubuntu installtion:

(parted) mkpart pmos ext4 50.0GB 126GB
mkpart pmos ext4 50.0GB 126GB

The output will look like this:

(parted) print free
print free
Model: SAMSUNG KLUDG4UHDC-B0E1 (scsi)
Disk /dev/block/sda: 126GB
Sector size (logical/physical): 4096B/4096B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name             Flags
        12.3kB  24.6kB  12.3kB  Free Space
 1      24.6kB  32.8kB  8192B                switch
 2      32.8kB  65.5kB  32.8kB               ssd
 3      65.5kB  98.3kB  32.8kB               dbg
 4      98.3kB  131kB   32.8kB               bk01
 5      131kB   262kB   131kB                bk02
 6      262kB   524kB   262kB                bk03
 7      524kB   1049kB  524kB                bk04
 8      1049kB  1573kB  524kB                keystore
 9      1573kB  2097kB  524kB                frp
10      2097kB  4194kB  2097kB               countrycode
11      4194kB  8389kB  4194kB               misc
12      8389kB  12.6MB  4194kB               vm-data
13      12.6MB  16.8MB  4194kB               bk06
14      16.8MB  25.2MB  8389kB               logfs
15      25.2MB  33.6MB  8389kB               ffu
16      33.6MB  50.3MB  16.8MB               oops
17      50.3MB  67.1MB  16.8MB               devinfo
18      67.1MB  83.9MB  16.8MB               oem_misc1
19      83.9MB  101MB   16.8MB  ext4         metadata
20      101MB   134MB   32.9MB               bk08
21      134MB   168MB   34.2MB               splash
22      168MB   201MB   33.6MB               bk09
23      201MB   9328MB  9127MB               super
24      9328MB  9328MB  131kB                vbmeta_system_a
25      9328MB  9328MB  131kB                vbmeta_system_b
26      9328MB  9396MB  67.1MB               logdump
27      9396MB  9530MB  134MB                minidump
28      9530MB  9664MB  134MB                rawdump
29      9664MB  10.7GB  1074MB  ext4         cust
30      10.7GB  10.9GB  134MB   ext4         rescue
        10.9GB  10.9GB  786kB   Free Space
31      10.9GB  50.0GB  39.1GB               userdata
32      50.0GB  126.0GB  76.0GB  ext4         pmos
        

Exit the parted tool and reboot once again.

Now we need to check which slot Android is installed.

NOTE: The concept of "slot" probably unfamiliar for you, since it was included in Android 10 as a feature, which called "Dynamic Partitions". Dynamic partitions are a userspace partitioning system for Android. About its further infomations, located here.

You can check this infomation via fastboot . Command is listed below:

fastboot getvar current-slot
current-slot: b
Finished. Total time: 0.004s

Force select Slot A as active slot:

fastboot set_active a
Setting current slot to 'a'                        OKAY [  0.049s]
Finished. Total time: 0.064s

Now, we are ready to flash the system image. But before we start, we need to disable Android Verified Boot (AVB) feature, otherwise it will prevent booting Ubuntu system.

AVB is implementation of verified boot process, current version (since Android 8 Oreo) is called AVB 2.0. Verified boot is a process of assuring the end user of the integrity of the software running on a device. It typically starts with a read-only portion of the device firmware which loads code and executes it only after cryptographically verifying that the code is authentic. It also helps in implementing rollback protection.

More information and technical details, located here.

Flash the vbmeta with vbmeta_disabled.img to disable this feature:

fastboot flash vbmeta_a vbmeta_disabled.img
Sending 'vbmeta_a' (4 KB)                          OKAY [  0.007s]
Writing 'vbmeta_a'                                 OKAY [  0.003s]
Finished. Total time: 0.048s

Then, flash rootfs images:

fastboot flash pmos /path/to/rootfs.img

Chrooting new system

NOTE: These steps can be done on a regular Android system, but you need to get your device ROOTED. Either Magisk or KernelSU is OK.

To finish installing our system, we need to use chroot container to continue our setup.

According to Wikipedia and Arch Wiki, a chroot is an operation that changes the apparent root directory for the current running process and their children. A program that is run in such a modified environment cannot access files and commands outside that environmental directory tree. This modified environment is called a chroot jail.

Download Orangefox or TWRP recovery first: https://drive.google.com/file/d/1gCNtoDMNCAmMR61xegvCC3mxv28gMJbi/view?usp=drive_link

Now, let's boot recovery image temporally:

fastboot boot /path/to/recovery.img

Once the recovery is booted, you are ready to setup a new chroot container. Go to "Advanced" tab, tap "Terminal" to enter terminal, and you are ready to go.

Prepare new root location

The chroot target should be a directory which contains a file system hierarchy.

In Android recovery, this directory would be /mnt. However, on Android, the /mnt directory is occupied by other several important directories, so you'll need to create another empty folder for chrooting.

Run lsblk and note the partition layout of your installation. It will be usually something like /dev/sdXY.

Mount the file system:

# mount /dev/sdXY /mnt

If you have an EFI system partition and need to make changes in it (e.g. updating the vmlinuz or initramfs images):

# mount /dev/sdXZ /mnt/efi

Then, continue on your recovery ( or Android ) session.

Usage

First, let's mount the temporary API Filesystems:

# cd /path/to/new/root
# mount -t proc /proc proc/
# mount -t sysfs /sys sys/
# mount --rbind /dev dev/

Warning: When using --rbind, some subdirectories of dev/ and sys/ will not be unmountable. Attempting to unmount with umount -l in this situation will break your session, requiring a reboot. If possible, use -o bind instead.

Next, to change root into /path/to/new/root using default sh shell:

chroot /path/to/new/root /bin/bash

Then, we need to fix the permission issues to get chroot fully working under Android or Android recovery:

Simply remount root filesystem:

mount -o remount,exec /path/to/new/root

Finally, chroot into your system:

chroot /path/to/new/root /bin/bash

Since this method require UEFI firmware to boot your system, you need to compile the UEFI firmware for your tablet. Follow this guide to do so.

If you have compiled UEFI firmware, you still need to install a bootloader ( e.g. GRUB ) to load the kernel and start the system. On your chroot container, enter this command to install bootloader:

sudo apt install grub-efi grub2-common efibootmgr

sudo grub-install --target=arm64-efi --boot-directory=/boot    #Replace /boot with your EFI mountpoint.
sudo grub-mkconfig -o /boot/grub/grub.cfg 

Then, type exit to exit chroot, and type reboot bootloader to reboot your tablet.

Now, flash your UEFI firmware and reboot your tablet:

fastboot flash boot /path/to/uefi_image

Ensure that the paths and commands are correctly adjusted to fit your system configuration. Once the bootloader installation is complete, verify that the UEFI firmware and bootloader are functioning by rebooting the device and selecting the appropriate boot option from the UEFI menu. This will confirm a successful setup and enable your tablet to boot into the new system environment.