[Xiaomi Mi 9 ROMs, Kernels, Recoveries, & Other Dev] NickPower:
Thanks for all your support! :)

However, I already tried that (cDroid did not work). I tried also the iron-kernel with magisk (did also not work). The only thing I did not install is the google stuff. Maybe I need this?

I currently have a look into the kernel sources.

I don't understand where the device tree file of the Xiaomi mi 9 device exists. I thought it would be located somewhere here:

https://github.com/flackback/PixonKernel/tree/main/arch/arm64/boot/dts/qcom

Something like sm8150-xiaomi-cepheus.dtb. It's not there.

However, there is a very interesting project of mainlining the device:

arm64: dts: qcom: Initial Xiaomi Mi 9 support (cepheus) (4870a82a) · Commits · Qualcomm Snapdragon 855 Mainline / Linux · GitLab

Add initial support for Xiaomi Mi 9 smartphone, based on Qualcomm SM8150 (Snapdragon 855) chipset. These series adds support for the following features: * reserved-memory map * debug UART *...

gitlab.com

Maybe I can try booting postmarketos. However, I guess the wifi is also missing:

Xiaomi Mi 9 (xiaomi-cepheus) - postmarketOS Wiki

wiki.postmarketos.org

Qualcomm Snapdragon 855 (SM8150) - postmarketOS Wiki

wiki.postmarketos.org

Can you maybe give me your dmesg output, so I can have a look what is different between our devices? Could you also suggest which ROM/Kernel I could try? How do you do kernel developing on android devices?

Edit:

I guess this is also useful:

ARM64: dts: import Xiaomi changes · EcrosoftXiao/kernel_xiaomi_cepheus@80c61f1

Change-Id: I32d48419b81d893c7e86f9ec0247dd8c6920d67d

github.com

Edit 2:

I guess the WiFi "Qualcomm Technologies Inc Q6 Integrated connectivity Platform Driver" is needed.

Documentation/devicetree/bindings/cnss/icnss.txt - kernel/msm - Git at Google

Looks like it is there:

PixonKernel/arch/arm64/boot/dts/qcom/sm8150.dtsi at main · flackback/PixonKernel

<PixonKernel> based CAFest <KneipKernel> - Cepheus Updated to CAF tag 'LA.UM.9.1.r1-11500.02-SMxxx0.QSSI12.0' with android-4.14-stable & f2fs-stable merged /* alert FOR...

github.com

Driver:

drivers/soc/qcom/icnss.c - kernel/msm - Git at Google

Edit 3:

The kernel had several changes:

History for drivers/soc/qcom/icnss.c - flackback/PixonKernel

<PixonKernel> based CAFest <KneipKernel> - Cepheus Updated to CAF tag 'LA.UM.9.1.r1-11500.02-SMxxx0.QSSI12.0' with android-4.14-stable & f2fs-stable merged /* alert FOR...

github.com

Looking at an older one:

History for drivers/soc/qcom/icnss.c - zclkkk/kernel_xiaomi_sm8150

CAFest <MikaKernel> for Raphael/Cepheus Updated to CAF tag LA.UM.9.1.r1-11700-SMxxx0.0 with android-4.14-stable & f2fs-stable merged /* alert FORCE PUSH */ /* OSS Only */ - History for ...

github.com

I would just revert some commits. However, I have no idea how kernel development on android works. Do you also use the same driver? A dmesg output and /sys/ would be very helpful.

The last three commits of the pixon kernel are not in the official qualcomm 4.14 stable tree present:

https://android.googlesource.com/kernel/msm/+log/refs/heads/android-msm-coral-4.14-android12/drivers/soc/qcom/icnss.c

All the async stuff looks suspicious:

soc/qcom: move icnss_initialize to async probe · flackback/PixonKernel@7c63c59

To reduce boot time to first stage. Before: [ 1.221918] init: init first stage started! After: [ 1.199159] init: init first stage started! Bug: 129688998 Test: reboot 100 times, camera, wi...

github.com

Maybe I will use this to compile my own kernel:

[REFERENCE] How to compile an Android kernel

Introduction Hello everyone, I will be going over how to compile a kernel from beginning to end! Prerequisites: A Linux environment (preferably 64-bit) Knowledge of how to navigate the command line Common sense A learning spirit, there will be...

xdaforums.com