Can't mount system as r/w!

SkinJob · Nov 16, 2015

Got a problem with my Huawei Y530 that I can't get past. It's running stock ICS 4.3. I rooted the phone but obviously, without recovery, since recoveries and custom ROMs don't exist for the Huawei Y530, far as I know. I am using the latest SuperSU Pro (4.6) for superuser, and "Root Checker" confirms I'm rooted. The problem is, things like Link2SD mount scripts won't work, because the system is read only. I installed the latest version of BusyBox, FWIW, and it (eventually) said it installed correctly. I tried running Terminal Emulator commands to mount the system as rw, but got blocked with the error "read only filesystem".

Is there a way to mount the system as r/w, on stock ROM and without a custom recovery/bootloader installed?

scary alien · Nov 16, 2015

Exactly what commands did you type into the Terminal Emulator session?

Brian706 · Nov 16, 2015

You might also consider trying an app to mount the system r/w: https://play.google.com/store/apps/details?id=com.blogspot.superthomaslab.mountsystemrorw&hl=en

scary alien · Nov 16, 2015

^^^ +1, Brian!

I thought about recommending something like that (even my own app tries to do that, but changes in Android 4.2+ for multi-user support caused mount contexts (and other stuff) from being shared across apps; Chainfire supports a way to do this and hopefully the above mentioned app properly implements that, but I never could get it to work on my app

). My app works okay to remount /system (or rootfs) for Android versions before 4.2.

Anyway, the OP should be able to do it manually, some I'm hoping it's just a typo...

Also @SkinJob, please list/provide the output of the mount | grep /system command.

Thanks!

SkinJob · Nov 16, 2015

scary alien said:
Exactly what commands did you type into the Terminal Emulator session?

There were two:

"fastboot oem get-bootinfo”

" fastboot oem unlock "

The system remains read-only.

scary alien · Nov 16, 2015

Well, you need specific mount commands to remount your /system partition into read/write mode--fastboot has nothing to do with that--at least in this specific context of remounting the system partition in read/write mode.

Have you tried the app that @Brian706 linked to above?

scary alien · Nov 16, 2015

Also, you can try doing the following command from and adb shell or Android Terminal Emulator prompt:

shell@hammerhead:/ $ su
root@hammerhead:/ # mount | grep /system
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,seclabel,relatime,data=ordered 0 0
root@hammerhead:/ # mount -o remount,rw /system
root@hammerhead:/ # mount | grep /system
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 rw,seclabel,relatime,data=ordered 0 0

(that's an example for my Nexus 5)

Be aware that this may only affect the mount status that your shell prompt sees--i.e., changes to Android in version 4.2+ impacted how a remount command would/could be seen by other processes.

Notice how the mount state/status changes from "ro" to "rw".

Cheers!

SkinJob · Nov 16, 2015

Ok, well this command: mount | grep /system

gives me this:

/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,relatime,data=ordered 0 0
root@hwY530-U051:/ #

This command: mount -o remount,rw /system

gives me: "Read Only File System"

(thus repeating the mount | grep command gives me "ro" in the output)

I tried 2 different apps that promise to mount the system as r/w. Both of them stated they successfully did that!

But both of them lied to me. :-( The rooted 4.3 system remained read-only.

I know little, but I'm inclined to think that one or more of the following has to do with the system remaining read only:

1. Used the Chinese "KingoRoot" to unroot (but later used another app that deleted KingoRoot and installed SuperSU)
2. Can't unlock bootloader.
3. No custom (CWM) recovery

I've only been rooted a few days, so I have never confirmed the system was ever anything but read-only.

scary alien said:
Also, you can try doing the following command from and adb shell or Android Terminal Emulator prompt:

shell@hammerhead:/ $ su
root@hammerhead:/ # mount | grep /system
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,seclabel,relatime,data=ordered 0 0
root@hammerhead:/ # mount -o remount,rw /system
root@hammerhead:/ # mount | grep /system
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 rw,seclabel,relatime,data=ordered 0 0

(that's an example for my Nexus 5)

Be aware that this may only affect the mount status that your shell prompt sees--i.e., changes to Android in version 4.2+ impacted how a remount command would/could be seen by other processes.

Notice how the mount state/status changes from "ro" to "rw".

Cheers!

scary alien · Nov 17, 2015

Did you change to root (type the "su" command) prior to trying the "mount..." command?

You must be root to remount /system in read/write mode.

Also, like I said, you likely cannot make remounting /system in read/write mode "stick" across different processes that requested them to be mounted in a different mode.

So, type the commands I provided above and paste the results/session here so we can see what is going on.

Thanks!

edit: the mount command that I provided might not work, but I need to see the result of the above before showing you a new command.

SkinJob · Nov 17, 2015

Yes, I'm aware that I need to be root before issuing such high security commands, so I did type "su" before the fastboot / grep commands. The result of the grep command I posted above. The exact result of the remount command is:

Read-only file system 255|root@hwY530-U091/ #

So even if it only sticks for 30 seconds, I would still consider it progress, as I still have not actually ever been witness to the file system mounting as r/w. Needless to say, this situation is causing havoc with my Link2SD setup (Link2SD won't mount certain things until fully booted, because of the r/w lockout).

scary alien · Nov 17, 2015

Hmm, this is all very odd since you would have needed to modify /system in order to root (at least that's the traditional paradigm--that's going to change by the way with newer, "systemless" root methods, but not relevant here).

Sorry I didn't notice your "#" prompt from what you pasted in the prior post(s)...[that would have told me you had done the "su" thing].

Okay, let's try this mount command instead:

mount -o remount,rw -t ext4 /dev/block/platform/msm_sdcc.1/by-name/system /system

That's obviously specific to your device partition instead of the generic mount command I gave you before.

If this doesn't work then there's some other agent involved in keeping your partitions read-only (not the first time we've seen this, but those devices that also had this problem also only had temporary root).

Brian706 · Nov 17, 2015

scary alien said:
If this doesn't work then there's some other agent involved in keeping your partitions read-only (not the first time we've seen this, but those devices that also had this problem also only had temporary root).

I have no idea if this could be relevant or not but it never hurts to throw thoughts out there when troubleshooting... I have seen in some of the recent HTC threads that this is being done at kernel level. In other words, a custom kernel is required to make the system partition writable.

I'm not 100% that my recollection is right on this, I've just seen something like this in passing a few times recently.

SkinJob · Nov 17, 2015

Say, that last command actually worked! Temporarily! There was no return message... so I tried changing permissions on the 'busybox' file in the system partition... it finally allowed this! But then, when I tried changing it back... nope! I redid the command and tried creating a mount script in Link2SD, and still no go. I currently can not get the filesystem to open back up again as r/w.

But this does give me hope that it's maybe possible to do this permanently! So I might have "temporary root"? I tried root checkers from the app store, and they seem to indicate I have root. Perhaps they're not that accurate. Any way to go full root on the Huawei, you think?

Brian706: A custom kernel would be great but... I can't even find a custom ROM for the Huawei Y530! Never mind custom ROM... I can't find a custom recovery! Never mind custom recovery, I can't unlock the bootloader! (Actually, I'm trying to get Huawei to send me the unlock code... but they seem to want me to send them my first unborn child, before they will consider helping me with that! On top of which, they feel it necessary to warn me that unrooting my Huwaei will cause a great tsunami where I live, and make my family sterile for generations to come....).

scary alien · Nov 17, 2015

Excellent!

Did you try changing permissions from the same shell prompt as you did the remount?

edit: I'm kinda guessing you did based on how you phrased things...anyway, a little progress

.

SkinJob · Nov 17, 2015

No, but I did try this now. After doing the "mount -o remount,rw -t ext4 /dev/block/platform/...." remount, I tried:

chmod 644 /system

What it does is cause my phone to go nuts, 'til I have to pull the battery.

Maybe that wasn't the right command?

scary alien · Nov 17, 2015

Yeah, you need to be very careful about changing things with out the benefit of being able to restore/recover with a Nandroid backup...

Why are you trying to re-secure the entire /system directory (vs. a specific file or folder inside it)?

SkinJob · Nov 17, 2015

scary alien said:
Yeah, you need to be very careful about changing things with out the benefit of being able to restore/recover with a Nandroid backup...

Why are you trying to re-secure the entire /system directory (vs. a specific file or folder inside it)?

Well I was trying to give the green light to Link2SD. Which is my main reason for trying to open the system up to writes, so it can create the mount script required to link apps to the SD. Of course even if this did work long enough to get L2SD to create the script, I don't suppose any of it would work once I rebooted. I really need to do this on a permanent basis or not at all!

Maybe I'll go and research people with "temporary root" and see what, if anything, they've done to try to get out of this limbo status.....

Can't mount system as r/w!

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