[Huawei P9 ROMs, Kernels, Recoveries, & Other Devel] kundifon:
GAPPS installation​

If you need, Gapps can be instaled. This rom is suitable for them.

I install NikGapps. Also working are MindTheGapps - I only noticed old play store. Someone reported that bitGapps work for him – I did’t manage to install them successfully. Absolutely don’t aspect that any gapps package will work – I have tested myself all of them.

First of all a comprehensive clean up is necessary. You need enough free space on /system partition and later install missing apps back from (play/aurora/fdroid) store.

(Some apps are really useless and I recommend way better open surce alternative as Simple mobile tools, especially Simple gallery pro)

Fresh instalation​

At fresh install of this custom rom, flash the rom image and TWRP recovery for android 8 in same session.

TWRP for Oreo P9-EVA-8.0.0-TWRP-v4.img: https://www.androidfilehost.com/?fid=1322778262903998750 (you used it when you rebrand and get phone on EMUI 8 firmware (https://xdaforums.com/t/rebrand-update-tool-hwota7-p9-eva.3820849/#post-77161313))

Get device into fastboot mode.

fastboot flash system <name of the rom img file>.img
fastboot flash recovery_ramdisk P9-EVA-8.0.0-TWRP-v4.img

boot to TWRP with power + volume up.

Go to Mount and mount /system partition and /external sd card. Then go to Advanced/File manager.

Now you have to clean all traces of microG and free up additional space. Below is the list what I have deleted. (Ofcourse some bloatware bodered me) It's not neccessery all this but you have to provide enough free space, that's the point.

https://xdaforums.com/t/rom-treble-microg-lineageos-16-0-for-huawei-p9.4078383/page-33#post-87963027

/system/app/AuroraStore/AuroraStore.apk
/system/app/Calendar/Calendar.apk
/system/app/Email/Email.apk
/system/app/eSpeakTTS/eSpeakTTS.apk
/system/app/GSFProxy/GSFProxy.apk
/system/app/IchnaeaNlpBackend/IchnaeaNlpBackend.apk
/system/app/messaging/messaging.apk
/system/app/NominatimNlpBackend/NominatimNlpBackend.apk
/system/app/privacy-friendly-netmonitor/privacy-friendly-netmonitor.apk

/system/etc/permissions/privapp-permissions-com.android.vending.xml
/system/etc/permissions/privapp-permissions-com.google.android.gms.xml

/system/priv-app/AuroraServices/AuroraServices.apk
/system/priv-app/Dialer/Dialer.apk
/system/priv-app/FakeStore/FakeStore.apk
/system/priv-app/Gallery2/Gallery2.apk (+ subfolder lib)
/system/priv-app/GmsCore/GmsCore.apk
/system/priv-app/Recorder/Recorder.apk

Now you can instal NikGapps with TWRP. Wipe dalvik/cache at end.

Get device into fastboot mode and flash stock recovery back. Download from here: https://www.androidfilehost.com/?fid=1395089523397898706

fastboot flash recovery_ramdisk EVA-b540-EMUI-RECOVERY_RAMDIS.img

Get into stock recovery by press and hold Power+Vol.Up where you do the factory reset. Then boot to the system for first time.

Update procedure​

When you flash new build of this rom, you have to repeat all steps above. Only omit factory reset at the end.

Gapps as Magisk module​

Alternatively you can install Gapps as Magisk module.

In this case for me only liteGapps were working. (lite package is smaller than core). I only noticed that contact sync wasn't working.

I haven't tested, but should works if you install GoogleContactsSyncAdapter separately bevor. See my previous post how to do this. Do factory reset and then continue with Magisk and liteGapps.

HWGSIpartitionKit to resize huawei system partition​

Just to mention another alternative way. You can use HWGSIpartitionKit to resize huawei system partition.

https://xdaforums.com/t/huawei-partition-kit-enlarge-system-partition.4545993/#post-88053461

Thank you all for your help

@MSe1969 , @Tecalote , @lo_ol , @zgfg , @AltairFR , @golvelliuscs , @Nicknackpaddywack101

Some related things:​

The same warning belongs also here. Most likely not, but sometimes things can go wrong. Since you are switching between TWRP and stock EMUI recovery, it is possible that you end up in boot loop. Backup your data!

Just flash back stock recovery, do factory reset and working system is back.