Enable UEFI on any Linux distributions

A simple user guide helps you to enable UEFI boot on your tablet.

Get the Device Tree config file

In computing, a devicetree (also written device tree) is a data structure describing the hardware components of a particular computer so that the operating system's kernel can use and manage those components, including the CPU or CPUs, the memory, the buses and the integrated peripherals.

Device tree is widely used on ARM64 platform when it uses Linux kernel, instead of ACPI. The latter can be found on most x86_64 based devices.

Systems which use device trees usually pass a static device tree (perhaps stored in EEPROM, or stored in NAND device like eUFS) to the operating system, but can also generate a device tree in the early stages of booting.

On Renegade Project's UEFI firmware, the device tree is used when your device is booting Linux kernel via EFI stub. To get the device tree file, we need to look up it in kernel repository. So open your terminal, and type this command, it will simply download the whole repository and store it on your disk:

git clone https://github.com/maverickjb/linux-6.1.10.git

git clone https://gitlab.postmarketos.org/panpanpanpan/sm8150-mainline.git

git clone https://gitlab.com/sm8150-mainline/linux.git 

NOTE: if you want to use the latest mainline kernel as daily driver:

• Driver for the PM8150B charger is broken in mainline, the only way to charge your tablet is by simply fixing the In8000* fast charger driver for mainline. About the patch files, they're located here, for fixing the charger, see below ( 6.14 only, No longer needed to patch for kernel 6.15 or above) ;

• Based on my personal tests, microphones are available, but unusable. Because the record volume is extremely LOUD, no matter which volume you've selected. If you keep using it (as for now), you will damage your ears and speakers !

• Real time clock (RTC) is working, but a manual patch is required. (No longer needed to patch since kernel 6.15 or above)

Once it finished, go to the repository's directory. We need to find the proper device tree file that ended with file extension name (*.dts). It is stored under arch/arm64/boot/dts . cd into this directory, find the DTS file named "sm8150-xiaomi-nabu.dts".

Now, let's install some basic tool for compiling the Linux kernel.

On Ubuntu and other Debian-based distributions:

sudo apt build-dep linux linux-image-unsigned-$(uname -r)

Unfortunately, the above does not install all of the necessary dependencies. The current Disco Dingo release requires the following additional packages.

• sudo apt install libncurses-dev gawk flex bison openssl libssl-dev dkms libelf-dev libudev-dev libpci-dev libiberty-dev autoconf llvm gcc-aarch64-linux-gnu

If you are going to be using git, install it via:

• sudo apt install git

This is an Ubuntu-specific hint. For Debian-based distributions, skip readng this.

The above command requires your system to have the correct deb-src lines in /etc/apt/sources.list. For example, on Disco Dingo you should have:

• deb-src http://archive.ubuntu.com/ubuntu disco main
  deb-src http://archive.ubuntu.com/ubuntu disco-updates main

On Arch Linux (and distributions based on it):

Install the base-devel meta package, which pulls in necessary packages such as make and gcc. It is also recommended to install the following packages, as listed in the default Arch kernel PKGBUILD: xmlto, kmod, inetutils, bc, libelf, git, cpio, perl, tar, xz.

sudo pacman -S base-devel make gcc git gcc-aarch64-linux-gnu

Now compile the DTS file into DTB files:

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- dtbs

You should have the Device tree files now.

Compile the Linux kernel

Why you need to fix In8000 charger for nabu ?

Well, basically, it's a pun. You have a tablet powered by a Li-Lon Battery, and we often call them "E-tablet". As for nabu, it's an E-tablet, it's a char-Ger ! Get it?

Before you start your compilation, you need to patch the kernel for charger and RTC feature.

Navigate to your kernel repository to continue:

git apply /path/to/rtc.patch        #For RTC.
git apply /path/to/0003-NABU-dts-enable-ln8000-charger-reduce-charge-voltage.patch        #For charger.

Simply enter these commands on terminal:

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu xiaomi_nabu_maverick_defconfig    #For mainline kernel, its make defconfig sm8150.config
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- 
make ARCH=arm64 install INSTALL_PATH=../install/boot
make ARCH=arm64 dtbs_install INSTALL_DTBS_PATH=../install/boot/dtbs
make ARCH=arm64 modules_install INSTALL_MOD_PATH=../install

Notice the Image.gz is the Android kernel image we won't use. After compiling kernel, you will find the two files we need: a sysmap file and the final kernel image (name begin with "vmlinuz") . Copy them to your tablet's EFI directory.

sudo cp config-6.1.10-nabu System.map-6.1.10-nabu vmlinuz-6.1.10-nabu /boot

You should have these files:

ls
System.map-6.1.10-nabu+    vmlinux-6.1.10-nabu+ initrd.img

Assign an ESP 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

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.

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

mkpart esp fat32 50.0GB 51GB
mkfs.fat -F32 -s1 /dev/block/sda32
set 32 esp on
mkpart ubuntu   51GB 100GB

Do sgdisk --resize-table 64 /dev/block/sda if you need to extend the number of partitions from 32 to 64.

Mount EFI partition

First, check the UUID of your partition:

[[zhongli@mipad5 ~]$ sudo blkid /dev/sda31
/dev/sda31: LABEL_FATBOOT="ESPNABU" LABEL="ESPNABU" UUID="EE48-EE55" BLOCK_SIZE="4096" TYPE="vfat" PARTL
ABEL="esp" PARTUUID="27aedc83-2799-44fd-a50a-247667540570"
[[zhongli@mipad5 ~1$ sudo blkid /dev/sda33
/dev/sda33: UUID="9260d19d-ffb8-448d-90d7-0bc5bde4e0b7" BLOCK_SIZE="4096" TYPE="ext4" PARTLABEL="arch" P
ARTUUID="15a5fe14-5057-40d1-a894-91a8aa2d57cb"

Modify fstab to use these UUIDs above:

cat /etc/fstab
# UNCONFIGURED FSTAB FOR BASE SYSTEM
UUID=9260d19d-ffb8-448d-90d7-0bc5bde4e0b7 /               ext4    errors=remount-ro 0       1
UUID=EE48-EE55  /boot/efi       vfat    umask=0077      0

Compile UEFI firmware

We will use Renegade Project EFI firmware for example. Clone the repository to your disk:

An alternative choice is Aloha firmware, which is based on Microsoft's MU firmware. It demonstrates an AArch64 UEFI implementation for hacked devices with Qualcomm silicons. Currently it is able to boot Windows and Linux. Please be aware that devices with no dsdt support have limited support.

For instructions about how to compile UEFI firmware and flashing it, they are located here. You can also download their prebuilt binaries at here.

git clone --recursive [e-mail]:edk2-porting/edk2-msm.git

Replace the dtb file "sm8150-xiaomi-nabu.dtb" in "edk2-msm/Platform/Xiaomi/sm8150/FdtBlob/nabu/" with the kernel DTB file "sm8150-xiaomi-nabu.dtb" which you used in your kernel repository. rename to "sm8150-xiaomi-nabu.dtb" and build image:

./build.sh -d nabu

You will receive a boot image. Flash it to boot partition:

fastboot flash boot /path/to/image

Then, install GRUB onto your disk in your Linux distributions:

For Ubuntu and other Debian-based distributions:

sudo apt install grub-efi grub2-common efibootmgr
sudo grub-install --target=arm64-efi --boot-directory=/boot
sudo grub-mkconfig -o /boot/grub/grub.cfg

For Arch Linux and Arch-based:

sudo pacman -S grub efibootmgr
sudo grub-install --target=arm64-efi --boot-directory=/boot
sudo grub-mkconfig -o /boot/grub/grub.cfg

For Alpine and Alpine-based:

sudo apk add grub grub-efi efibootmgr
sudo grub-install --target=arm64-efi --boot-directory=/boot
sudo grub-mkconfig -o /boot/grub/grub.cfg

DTB Overwrite

On recent kernels (6.12 or above), device trees from mainline kernels may not work perfectly on your tablet, even the device tree is compatible with older kernels. The most common affected feature is charger.

Since recent Arch Linux ( Now it's the only option you can choose by default ) images are shipped with a pre-built kernel, it would be easy to make your system bootable via UEFI firmware. But you can also continue using your custom kernel to finish this part. Using a bootloader supports overwriting DTB files is useful when you have multiple kernels installed.

Install bootloader

We'll use systemd-boot as an example:

sudo bootctl install

Now the bootloader is installed. But we need to write a configuration file to tell bootloader how to boot system properly.

Tip: After changing the configuration, run bootctl (without any arguments) to make sure that systemd-boot will be able to parse it properly.

Adding loaders for systemd-boot

systemd-boot will search for .conf files in /loader/entries/ on the EFI system partition it was launched from and additionally the XBOOTLDR partition on the same disk.

Go to EFI system partition, then the loader directory, then entries . Using touch command to create a .conf file.

sudo touch Arch.conf    #Replace "Arch" With any name you want.

Write an configuration file, below is an example:

esp/loader/entries/arch.conf

title   Arch Linux
linux   /vmlinuz-linux        #Replace vmlinuz-linux with actual name of kernel.
initrd  /initramfs-linux.img
options root=/dev/sda32 pd_ignore_unused clk_ignore_unused rw
devicetree /devicetree-file.dtb    #Replace it with your actual name of your DTB file.

NOTE: Entries in esp/loader/entries/*.conf can only use files (e.g. kernels, initramfs, images, etc.) in esp/ and entries in boot/loader/entries/*.conf can only use files in boot/.

• systemd-boot does not accept tabs for indentation, use spaces instead.

• default and timeout can be changed in the boot menu itself and changes will be stored as UEFI variables LoaderEntryDefault and LoaderConfigTimeout, overriding these options.

Once you finished these steps above, reboot your tablet and check if it works.

Ubuntu specifics

Install GRUB on Ubuntu​

On recent Ubuntu images, these steps are no longer needed.

Install GRUB tools and generate RAM disk：

sudo apt-get install grub2-common grub-efi
sudo grub-install --target=arm64-efi --boot-directory=/boot

sudo apt install initramfs-tools
mkinitramfs -o /boot/initrd.img 6.1.10-nabu

Generate GRUB configuration file:

sudo grub-mkconfig -o /boot/grub/grub.cfg

After compiling the kernel and ensuring that the necessary files are moved to your tablet's EFI directory, reboot your device. During the booting process, access the boot menu. This may vary depending on your device, but typically involves pressing one of the function keys (e.g., F12, F9, or F2) right after powering on the device. From the boot menu, select "Ubuntu" .You'll see the GRUB boot menu, use Vol+ or Vol- keys to navigate, power button to confirm.

Boot menu.

Updating Kernel Parameters (Optional)

If you need to tweak kernel parameters for optimization or compatibility reasons, you can edit the grub configuration file. This file is usually found at /etc/default/grub. You would add your parameters to the GRUB_CMDLINE_LINUX_DEFAULT line. After editing, apply the changes with sudo update-grub and reboot for them to take effect.

Remember, keeping a backup of the original configuration files before making any changes is always a good practice. This precaution ensures you can revert to a working state in case anything goes wrong.