Linux filesystem on SD card
Support for ext4 formatted external sd cards describes writing an init.d script that:
mount -o rw,UID=1000 -t ext4 /dev/block/mmcblk1p1 /storage/extSdCard
Android device encryption tips
[Q] mount cryptfs? - xda-developers
In recovery, unlock an encrypted partition with:
setprop ro.crypto.state encrypted
vdc cryptfs checkpw 'your passphrase here'
mount -o rw /dev/block/dm-0 /data
Make sure to unmount /data.
Logs are in /dev/log/system and/ or (in a second shell) /dev/log/main.
