Native Arch Linux on Redmi 4X (santoni)

/*
 * Your warranty is now void.
 *
 * I am not responsible for bricked devices, dead SD cards,
 * thermonuclear war, or you getting fired because the alarm app failed. Please
 * do some research if you have any concerns about features and tampering with
 * the system before flashing it! YOU are choosing to make these modifications,
 * and if you point the finger at me for messing up your device, 
 * I will laugh at you.
 */

This project here aims to get Native Arch Linux running on the Xiaomi Redmi 4X (no chroot) I would recommend to use a USB stick or SD card to boot this, you can install it on the eMMC, but I prefer SD card more since you don't have to tamper with the eMMC.

If you cannot get it to boot, you should try to get /proc/last_kmsg.

Why are we doing this?

We're doing this because:

• We want to expand the device's lifespan.
• Android is running on a Linux kernel, so why this isn't possible?
• We really enjoy the challenge.

System Specs:

Part	Component
CPU	Qualcomm Snapdragon 435 - 8 Cores, 1.4 GHz
RAM	2/3 GB
GPU	Adreno 505
Storage	16/32 GB eMMC
Ext Storage	microSD - up to 128 GB
OS	Android 6.0 (launch) - Android 7.1
Other	Wi-Fi, Bluetooth 4.2, GPS

Full system specs: https://www.gsmarena.com/xiaomi_redmi_4_(4x)-8608.php#redmi-4x

What's working

• Booting
• Flashing (boot.img only tested)
• Display
• Wi-Fi + Hotspot
• USB Ethernet (local SSH, but also SSH via USB works)
• Sound
• Xorg
• DPMS for Xorg (screen going to sleep just fine)
• USB OTG
• Vibrator (/sys/class/timed_output/vibrator)

Not working (yet)

• Camera (broken in kernel? accessing /dev/video32 and 33 will crash the kernel)
• Modem
• GPS
• Accelerometer
• Light Sensor
• GPU (Freedreno, through if that doesn't work, we probably might stuck with libhybris until device's mainline kernel)
• Wayland DPMS (backlight stays on)

Bugs

• Framebuffer Console doesn't work.
• Power management doesn't work this moment, due to Qualcomm's so-called "Crypto Engine" for SDHCI interrupting the device from going to sleep.
• Framebuffer colors are messed up.
• /proc/last_kmsg is corrupted, through still readable.

Device Source:

• Kernel Source: https://github.com/Danct12/msm-3.18 <rel/msm-3.18-archlinux>
• Device tree: https://github.com/LineageOS/android_device_xiaomi_santoni

To do:

• Mainline the device (like what postmarketOS guys did) WARNING: There's always a risk of getting the magic smoke out of the device (by set the regulator settings wrong, we already have a case of fried device with the xiaomi-tissot), so this isn't going to happen anytime soon (if you're someone with a brave SOUL and determination, feel free to help out!)

All the changes and anything I got to work will be upstreamed to postmarketOS in order to help development.

Stay determined, $USER!

For more information in development (but also interested into getting Arch on other devices), join DanctNIX Discord: https://discord.gg/AvtdRJ3