[Sprint Samsung Galaxy S III] sponix2ipfw:
Functional ext4 for microSD extSdCard with just a few bumps left to smooth out !

The SPH-L710 Samsung Stock LJ7 TW 4.1.1 Android doesn't understand/support the change to ext4 external SD card (microSD) without a few things being done.

I'm working this out right now. So far I have manually been able to mount the newly created ext4 partition on the microSD card through adb, and after some chown/chmod I was able to go back to "Settings and Storage" and the "Mount SD Card" picked it up, and I was up and running ext4. But this didn't persist after a restart. So I'm looking into: /etc/vold.fstab MODS to keep it after restart right Now !!

If Some one else already has this perfected please chime in. I'm wanting to do most of the devices in the house this way when I get time because better performance, having a file system with a journal, and getting rid of thins like 4 Gig per file limitations is pretty Sweet in my humble opinion *Grin*

0) Assuming you already have your microSD card formatted ext4. I also happened to label mine extSdCard for the volume label within gparted

1) Can mount with:

mount -w -t ext4 /dev/block/mmcblk1p1 /storage/extSdCard/

2) To get the correct owner and permissions run:

chown root:sdcard_rw /storage/extSdCard

chmod 775 /storage/extSdCard

3) Should make the extSdCard owner/permissons match the regular internal sdcard you can verify this like so:

cd /storage/ && ls -l

drwxrwxr-x root sdcard_rw 2013-01-12 18:16 extSdCard

drwxrwxr-x root sdcard_rw 2013-01-12 17:05 sdcard0

4) After that you can go to the "Settings and Storage" to run "Mount SD" and you will have ext4 extSdCard Show up and it bring up the File System Status !! --> Until you reboot and it goes to crap because I don't have the vold.fstab edit/MOD complete _yet_ ... So, for now a boot script has been put in place to bring our external SD card back online during restart, so the system will acknowledges it, making the world a better place.

Example of how things look file system wise: mount | grep extSdCard

/dev/block/mmcblk1p1 /storage/extSdCard ext4 rw,relatime,user_xattr,barrier=1,data=ordered 0 0

5) Have not been able to resolve the vold.fstab to make this ext4 extSdCard matter fully Legit (in my opinion), but I did manage to make it remount the card on boot, so its online when the system comes up instead of having to manually mount it. Did this by -->

Added the following lines to the very bottom of: /etc/init.qcom.post_fs.sh

## sponix MOD to match with ktoonz kernel for better power management

stop mpdecision

## sponix MOD to mount extSdCard prior to GUI work around to make ext4 function

## read and write extSdCard mount

chown root:sdcard_rw /storage/extSdCard

chmod 775 /storage/extSdCard

mount -w -t ext4 /dev/block/mmcblk1p1 /storage/extSdCard

chown root:sdcard_rw /storage/extSdCard

chmod 775 /storage/extSdCard

## if you want read only extSdCard mount

## mount -r -t ext4 /dev/block/mmcblk1p1 /storage/extSdCard

Still attempting to automate the process so the Stock+root LJ7 can pick up the extSdCard _normally_ without having to do the mount command manually, but so far its kicking my butt. Also this is more a "General, or Question and Answer type Topic" the Kernel(s) obviously support ext4 the system fs uses/requires it *Grin*.. So we might get Our Friendly Neighborhood Moderator to Migrate it to the proper place to help others. Just hoping to get the last few bumps smoothed out, or find someone that already documented the process that I've overlooked *Grin*..

Current Known Issues: If you unmount the card through the "Settings | Storage | Umount SD" or by hand with umount, you will either need to reboot for it to reattach through the /etc/init.qcom.post_fs.sh boot script script addition, or will have to mount it manually if you want to keep the system up and running. Guess you could also probably just run the /etc/init.qcom.post_fs.sh as root from a terminal emulator (or adb).

Still searching for vold.fstab bits of wisdom but that will have to continue next weekend --> :cool:

Sexy and You Know it,

Keep on Flashing,

sponix2ipfw (sponix

:fingers-crossed: