At first I know it was said not to do, but I don't want to complain, only ask some things for better understanding (hopefully)
I did in twrp terminal the mkfs.f2fs on/cache (mmcblk1p24) and placed a modded ramdisk (fstab) in system. That worked as expected/hoped.
Then I edited the ramdisk a second time for system being f2fs, too.
Then I edited the updater-script of the rom zip to mount system with auto file system
Did the format command to system (mmcblk1p21) and tried to install the rom, but twrp told me that there were an error executing the update-binary.
A few other files worked, but the rom didn't work.
Am I right that even that our kernel can mount f2fs, the bootloader can't and so the system can't even load our kernel?
Edit: Here's a screenshot of diskinfo
Gesendet von meinem GT-I9505 mit Tapatalk