[Q] Asus Memopad ME301T CM11 encryption

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paul.greeff

Member
Apr 24, 2013
7
1
In a thread under the TF300T devices, nikybiasion, started a thread for the Unofficial Cyanogenmod 11.0 for ME301T. It's a beautiful ROM, with all the Cyanogenmod goodness I love in my Android devices.

I notice one issue in that although I can encrypt the data partition my device will not boot further after I entered the password. It gets stuck showing the little Android picture and never proceeds to the CM boot animation. I suspect it may be something specific to my device (something I did while playing with other roms). I'd appreciate it if someone can point me in the right direction in analysing this problem.

Usually I perform adb logcat to see what error messages pop up (very useful once when the data partition had no space left for the encryption metadata in the footer on the stock rom - my fault) but I have no idea how to get logs after rebooting when encryption successfully finished. So first step is I'd like to get to the logs - any idea how I can do this having rebooted after encryption is done?

Regards
Paul
 

paul.greeff

Member
Apr 24, 2013
7
1
More information on ME310T encrypted boot problem

I flashed the Crombi-KK rom today (wow, what an awesome compilation) but unfortunately I'm experiencing the same problem as before with booting with an encrypted data partition.

Fortunately adb responds as soon as Crombi starts to boot. Attached is the logcat.

Presumably the following points to the problem:
E/Cryptfs ( 131): unmounting /data failed
W/SocketClient( 131): write error (Broken pipe)
W/SocketClient( 131): Unable to send msg '200 6 -1'

I'm not sure what to make of it though. Any thoughts would be appreciated.

Regards
Paul
 

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paul.greeff

Member
Apr 24, 2013
7
1
Possible cause for non boot with encrypted data partition on ME301T

I think I might have found a possible cause for this problem.

As indicated above the error indicates that data cannot be unmounted.
E/Cryptfs ( 131): unmounting /data failed

It turns out data is used for temporary space
tmpfs /data tmpfs rw,seclabel,nosuid,nodev,noatime,size=131072k,mode=771,uid=1000,gid=1000 0 0

however it cannot be unmounted as there is another partition mounted under /data/wifimac
/dev/block/mmcblk0p5 /data/wifimac vfat rw,relatime,fmask=0077,dmask=0077,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0

If I unmount this directory before I enter my password the device boots normally. I have just tried this with Crombi-KK rom and will attempt to do the same with CM11 Unofficial for the ME301T.

Regards
Paul
 

paul.greeff

Member
Apr 24, 2013
7
1
Problem solved ME301T now boots past encryption

I still can't get logcat output from CM11 Unofficial. What I did notice with the Crombi-KK ROM is that as in the previous post the failure occurs when the /data directory fails to unmount before the encrypted partition is mounted.

On Crombi it also appears that Wifi is broken. It looks like /data/wifimac does not unmount. An application that needs to run in order to build nvram.txt, wifimacwriter, fails because the file /data/wifimac/wifi_mac is missing (partition mmcblk0p5). Creating this file solved this problem and Crombi seems to boot past encryption.

It is possible that in my vigorous flashing and wiping of various roms I whacked or corrupted the partition mmcblk0p5 containing this information. Although strictly not necessary, it seems wifimacwriter fails if the files don't at least exist.

In short, the fix is as follows:
Code:
# mount -t vfat /dev/block/mmcblk0p5 /mnt/sdcard/tmp/ # Any convenient mount point will do
# touch /mnt/sdcard/tmp/wifi_mac
# reboot

So it seems my hypothesis in post 1, that the problem might be specific to my tablet, was correct - I broke it. You may all disregard these 4 posts. Carry on, nothing to see here...