EXT4, F2FS and exFAT are filesystem types. By using Lsskernel, you have support for exFAT and F2FS.
For example we can format /data and /cache as F2FS on MagMa-NX without problems.
However, for microSD, only FAT32 is supported. In the case of Note5 and Note7 ports to HLTE, artas' (discontinued) ROM supports F2FS on microSD:
http://xdaforums.com/galaxy-note-3/development/6-0-1-touchwiz-marshmallow-note-3-t3349306
No other ports support it.
How did he do it? That's where I look to the ROM devs
.
See posts here for other devices:
http://xdaforums.com/showthread.php?t=2098427
http://xdaforums.com/showthread.php?t=2424900
Those are for pre-marshmallow, before we had "adopted storage" and "portable storage" options for microSD.
Running a command like this in Terminal on Magma-MX already works:
Code:
mount -t f2fs /dev/block/mmcblk1p0 /storage/extSdCard
But this is not "native" support, so no applications can access it unless they have root permissions.
Now this very well be something on the Lsskernel side (I've been experimenting with rebuilding the boot.img with a modified ramdisk with no success). But my understanding is for native support, it is a combination of kernel and ROM support. We can dive into artas' ROM and see what magic he's doing on his kernel.
Hope this helps.