[How To] Swap the mounting points on ICS (CM9) for emmc and sdcard.

mattisdada · Apr 11, 2012

This is a quick tutorial I want to write up based on a recent experience I've had recently with my micro sd-card. (More info on that below)

This how to shows how to switch between the internal sd card and the external sd cards mounting points (so the external is accessed via /sdcard, and the internal is accessed through /eemc)

The nuts and bolts how to:
0. Perform backups on System, i am not responsible for any damages or boot loops.
1. Download root explorer (or any other file explorer with root privileges)
2. Go to /system/etc, and mount R/W
3. Long press on vold.fstab and select Open With... , select Text Editor
4. You will find a line with sdcard in it a few times, change this section:

dev_mount sdcard /mnt/sdcard

To:

dev_mount emmc /mnt/emmc

5. Do the same thing with the emmc section:

dev_mount emmc /mnt/emmc

To:

dev_mount sdcard /mnt/sdcard

6. But you just flipped the first section around? Yes I did, this changes the mounting points. But not the original location of where it is being mounted......
7. Please don't change anything else in this file....
8. Reboot, enjoy!

I had to do this hax because the current nightly of CM9 doesn't support there being no external sd card, and mine got corrupt (eep!), it then continued to mount the internal sd card location to emmc instead (wtf?). So i did this quick hax so i could take pictures with the stock camera and use several applications which just default to the internal sdcard (and doesn't allow changing that).

Hope that helps some random Googlers......

Note: This has only been tested on CM9 Nightly apr-9th on SGSII, but i see no reason for this not work across all ROMs and devices( with ICS, the emmc thing wasn't on GB and below i don't think) as long as you don't do anything as foolish as change more than the lines specified above.

An example of a swapped file is (DO NOT COPY AND PASTE THIS, YOU PROBABLY WONT BE ABLE TO BOOT):

# internal sdcard
dev_mount emmc /mnt/emmc 11 /devices/platform/dw_mmc/mmc_host/mmc0/mmc0 encryptable_

# external sdcard
dev_mount sdcard /mnt/sdcard auto /devices/platform/s3c-sdhci.2/mmc_host/mmc1

Please note that the latest CM9 nightlies lets you do this from the system menu! This was written pre that advancement. This is for the curious and other ROMs/phones.

Zewsan · Apr 12, 2012

Is it possible to use something in the lines of:
dev_mount emmc /mnt/external_sd ? To just bind the external sd to the stock location?

Snakeforhire · Apr 16, 2012

If I understood your question right, that's the default behavior in CM7/9 so you don't need to change anything.
(internal gets mounted as /sdcard and external as /emmc. At least that's how it always behaved on my device -takes a bit of getting used to but it's manageable once you know the trick)

edit : aw sawry, mistook /mnt/external_sd for /mnt/sdcard. But it changes nothing besides the name of the mountpoint, easily adjustable.. Although why you would want to have it named like that is beyond me, it makes for more keys to hit when typing it... xD

gnan10 · Apr 16, 2012

Zewsan said:
Is it possible to use something in the lines of:
dev_mount emmc /mnt/external_sd ? To just bind the external sd to the stock location?

same doubt raised here ...is it possible to mount external sdcard to /mnt/external_sd instead of mnt/emmc...???
please need solution

mattisdada · Apr 16, 2012

Zewsan said:
Is it possible to use something in the lines of:
dev_mount emmc /mnt/external_sd ? To just bind the external sd to the stock location?

Its the same technique....

So remember this:

Format: dev_mount <label> <mount_point> <part> <sysfs_path1...>

So <label> doesn't really matter, but we may as well keep it sane (and have it the same name as the mount point)! And <mount_point> is where its mounted. Make sure the folder exists first though! leave <part> and <sysfs_path*> alone and it will work correctly.

So if you were to create a folder /mnt/hammertime , then make a line look something like this (taken from my example in first post)

dev_mount hammertime /mnt/hammertime auto /devices/platform/s3c-sdhci.2/mmc_host/mmc1

That will work correctly.

Hope that helps!

gnan10 · Apr 16, 2012

mattisdada said:
Its the same technique....

So remember this:

So <label> doesn't really matter, but we may as well keep it sane (and have it the same name as the mount point)! And <mount_point> is where its mounted. Make sure the folder exists first though! leave <part> and <sysfs_path*> alone and it will work correctly.

So if you were to create a folder /mnt/hammertime , then make a line look something like this (taken from my example in first post)

That will work correctly.

Hope that helps!

is there no any requirement of changing build.prop file after doing this....?????

HAvoktek · Apr 17, 2012

Ok I'll bite, late night tonight I'm going to flash back to AOKP....and give it a shot. It can't be that simple.....
Most certainly appreciate your effort...been looking for this for some time now.l!

mattisdada · Apr 17, 2012

HAvoktek said:
Ok I'll bite, late night tonight I'm going to flash back to AOKP....and give it a shot. It can't be that simple.....
Most certainly appreciate your effort...been looking for this for some time now.l!

I didn't think so either, but i had the problem, hoped it was like its Linux cousin and searched for fstab, i found it. Swapped the mounting destinations around. And voila, done.....

jeromepaez · Apr 21, 2012

Swapped but CWM Recovery still the same

Hi, first of all nice guide you did here.
Here's the thing: somehow somewhere by flashing nightlies i ended up
with /sdcard being treated as my external SD while /emmc was for internal.
So I wanted to fix that and using your guide although the other way around
I was able to make it as such: /sdcard = internal storage; /emmc = external storage.
ALL IS GOOD however when i booted to CWM recovery:
CWM still mounts my internal storage as /emmc.
SO in recovery internal storage = /emmc while when in CM9 internal storage = /sdcard

Is there anyway i can change CWM so that internal storage = /sdcard? to be more uniform and not confusing

mattisdada · Apr 21, 2012

jeromepaez said:
Hi, first of all nice guide you did here.
Here's the thing: somehow somewhere by flashing nightlies i ended up
with /sdcard being treated as my external SD while /emmc was for internal.
So I wanted to fix that and using your guide although the other way around
I was able to make it as such: /sdcard = internal storage; /emmc = external storage.
ALL IS GOOD however when i booted to CWM recovery:
CWM still mounts my internal storage as /emmc.
SO in recovery internal storage = /emmc while when in CM9 internal storage = /sdcard

Is there anyway i can change CWM so that internal storage = /sdcard? to be more uniform and not confusing

Yeah CWM doesn't read the /system stuff, it has its own partition....
I've got no idea sorry, but its just a little inconvenient in CWM thats all.... But im sure you can check it out... Just search for fstab when you figure out how to explore the recovery partition (I've got no idea

, short of modifying a flashable zip first and rekeying it.)

HAvoktek · Apr 21, 2012

Forgot to post back with my results, Got HFS & AOKP to see the changes, however something broke when I did a PC mount. After playing with the lines "Experimentation" if you will, I ended up needing to rebuild my partitions! No fault of yours, I just wanted to see if I can have that functionality through the whole phones usage and features eg. mounting to the PC.
Thanks for the guide though, I'm seeing now that some devs are including the option to use the internal memory via a menu select, I wonder how there implementing that.

mattisdada · Apr 21, 2012

Probably something very similar but programmatically instead of the haxy file editing method I'm noting to use

.

PC mounting is working as per normal for me here though...... (I don't have an external card right now so that may be a variable)

HAvoktek · Apr 21, 2012

mattisdada said:
Probably something very similar but programmatically instead of the haxy file editing method I'm noting to use .

PC mounting is working as per normal for me here though...... (I don't have an external card right now so that may be a variable)

That it is, cause I can see my internal, but it doesn't mount the external.

hfj00788 · May 4, 2012

Purpose

What is the purpose of this? Does it mount the EMMC so that the system thinks EMMC is actually an external sd card?

I am trying to figure out if there is a way to make the above mentioned happen. Or is there a way to re-partition it so that EMMC is used as system memory... or maybe even both? It seems that since ICS better integrates with on board memory, there would be a way to better integrate the internal memory of older devices with the system.

mattisdada · May 6, 2012

hfj00788 said:
What is the purpose of this? Does it mount the EMMC so that the system thinks EMMC is actually an external sd card?

I am trying to figure out if there is a way to make the above mentioned happen. Or is there a way to re-partition it so that EMMC is used as system memory... or maybe even both? It seems that since ICS better integrates with on board memory, there would be a way to better integrate the internal memory of older devices with the system.

This guide shows you how to "flip" the points. Several ROMs have it differently preconfigured. But if this is your current situation:

Code:

Emmc: External SD Card
SDcard: Internal SD Card

It will make it:

Code:

Emmc: Internal SD Card
SDcard: External SD Card

And vice versa obviously (its a flip).

This guide will do what your wishing it to do.

The folders sdcard and emmc (or there /mnt varient more closely) are just soft links, meaning they don't really exist, but just point to another location. We can modify which folder they are linked to in the fstab.void file.

bradman117 · May 21, 2012

so to make emmc to external_sd i change "dev_mount emmc /mnt/external_sd"?

Dungeon47 · May 22, 2012

Worked great on a Captivate running AOKP-36 right after a wipe data/factory.

bluefa1con · May 22, 2012

lol you need no guide on cm9
you can switch them in storage settings by a simple checkbox
its mentioned in team hacksung's FAQ

bradman117 · May 22, 2012

Im on CM9. Can someone post the code so i can just do a simple copy and paste? I wanna switch emmc to external_sd
(there is no storage settings simple checkbox for me)
Sent from my SGH-I997 using xda premium

mattisdada · May 23, 2012

bradman117 said:
Im on CM9. Can someone post the code so i can just do a simple copy and paste? I wanna switch emmc to external_sd
(there is no storage settings simple checkbox for me)
Sent from my SGH-I997 using xda premium

Never use a copy and paste for the file in this operation. You only need to modify partially two lines (which you can copy and paste from the OP).

Your just swapping two words around really. Its fairly easy, just follow the steps and it will work, it looks daunting at first if your not used to doing this sort of thing, but its fairly easy.

[How To] Swap the mounting points on ICS (CM9) for emmc and sdcard.

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