Help me understand installation procedure , please .

[Tomek0000]

I have found the description of xiaomi.eu installation in https://xiaomi.eu/community/threads/8-11-8.47488/ :

1. ROMs for devices with locked bootloader:
Wipe /data partition (NEVER wipe System or Persist!)

2. Installation via TWRP:
Install - Select zip

I know 2 types of installation clean and dirty.
The clean has to be initiated wipping/formating all partitions exept external card, the dirty we wipping cache, dalvik, data .

My first question.
If I install (2) xiaomi.eu without wipping anything , will the rom work correct with not compatible system data and cache ? If I will delete (1) only data , will the cache and dalvik not crash new installed rom ?

The second question is about not wiped system.
a. Can I install xiaomi.eu on every existing rom in the internal flash ? Each rom has own files in system and if I will not delete it ... what does it mean ? Xiaomi.eu will not install own data to system and will use system from previous installed rom ?
b. If xiaomi.eu do not have own system, what version of rom I have to install before installling xiaomi.eu ? Stock ? If stock , what android should I have 8.1 or 9 for each or specific version of xiaomi.eu ?
c. I read , xiaomi.eu is debloated . How is it possible if we do not wipe system before installing xiaomi.eu , and system is place where bloateware is installed ?

If someone will find a moment for answer my doubts, thank you.

 

[peterw35]

Clean and dirty does not depend on locked bootloader of TWRP.
if you switch ROM, (e.g. from MIUI global to Xiaomi.eu, or MIUI global stable to developer ROM) do a clean install, which means wipe cache, dalvik, data
if you upgrade (e.g. updating Xiaomi.eu from an older version to a new version), a dirty install should be fine. which means no need to wipe.

a. If you install xiaomi.eu, you are deleting whatever rom you currently have on your phone. so system will be replaced with new ROM files.
b. it does not matter what ROM you have before switching to xiaomi.eu. because you are deleting it in order to put xiaomi.eu on
c. read point a.

Also, as a side point:
1. if your phone has a locked bootloader, you will need to unlock it first. nothing can be done UNTIL your bootloader is unlocked. the purpose of bootloader lock is to prevent you from flashing ROM. keeping the phone secure.

 

[Tomek0000]

Thank you. As I understand , the process of first installation of xiaomi.eu does not need wipping system partition for security reason... if the instalation will fail , we have previous system not deleted , if it will finish with success , we have system partition wiped and new installed by xiaomi.eu installator.
Thank you for clarification.

 

[MeiGuddet]

System partition always will be automatically wiped by installing eu-ROM. Wiping cache/dalvik cache is normallly done by ROM-installation itself, so not necessary to be done manually when your phone is running smooth.
With first installation of eu-ROM coming from official China or Global ROM FORMAT DATA is necessary to remove encryption. This can't be done with wiping data partition.