I want to have access to an ext4 partition, without using Data2SD yet, on the SD card of my HTC Vision running the Virtuous Unity 1.3.0 ROM. I modded my /system/etc/vold.fstab file from this:
dev_mount sdcard /mnt/sdcard auto /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
To this:
#dev_mount sdcard /mnt/sdcard auto /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
dev_mount sdcard /mnt/sdcard 1 /devices/platform/goldfish_mmc.0 /devices/platform/msm_sdcc.4/mmc_host/mmc2
dev_mount e4vol /mnt/sdcard2 2 /devices/platform/goldfish_mmc.0
/devices/platform/msm_sdcc.4/mmc_host/mmc2
So I can get my second partition, with label e4vol, mount and usable on my Android device. Two issues, and I think one obviously has to do with the other.
I have tried remounting the root read-write and creating the mount point /mnt/sdcard2, but it is gone on reboot. Seems like Android might have in the past created such mounts with mount.conf. Now it does not exist on Gingerbread ROMS. Thoughts?
Is this all I would have to do to get my second partition mounted in Android, or do I also need to create /sdcard2 like /sdcard? I presume both are created as symlinks by vold as specified in this conf file, but I have not had time to check yet.
I would ask forums, but this seems like a developer question and this is the most recent release of the OS. It seems to change a lot from version to version of the OS. Thanks in advance for your patience and help.
UPDATE: So, moved the test mount to sdcard, and it did not work, even with a persistent mount point. So, not sure where I am going wrong.
Maybe you'll have to have a look into /init.rc.
There are some "mkdir /mnt/..."-statements. You only have to add your "mkdir /mnt/sdcard2" and "ln -s /mnt/sdcard2 /sdcard2" to this file.
But be careful when editing this file!!!
I looked at the vold source up to including Icecream-Sandwich: it’s final mount() system call is hardcoded to the “vfat” file system type. – Even if you get it to try the mount, it would fail.
I myself actually want to mount my ext4 SD card to /sdcard, because I regularly suffer from SD card FAT file system corruptions (and I’m not the only one having those with Android).
The alternative is: modify the init/boot process to just mount the partition where you want, bypassing vold.
Related
On my Samsung Note 10.1, I would like to be able to mount a different userdata partition. My goal is to achieve this at boot by modifying the init.rc script, since this seems to be setting up all file systems and mounting the partitions userdata, system, and so on. For example, there is a line mkdir /data 0771 system system, which sounds to me as if it sets up the mount point for the userdata partition. The userdata partition corresponds to block device /dev/block/mmcblk0p12.
Now, what I want is instead of mounting mmcblk0p12, I want to mount an image of mmcblk0p12, which I have placed on a µSD-Card inserted in the device. The µSD-Card is accessible via block device /dev/block/vold/179:17. This means that I would first need to mount the µSD-Card and then the image on the µSD-Card.
But this is where I fail. I can't figure out how to mount the µSD-Card in the init.rc, not to mention how to mount the image afterwards. I've added the line mount -t ext4 /dev/block/vold/179\:17 /mnt/extSdCard multiple times, but all it gives me is a boot loop.
So, does anyone know how to do this?
EDIT1: apparently the partitions get mounted in fstab.sdmk4x12, so I added the line /dev/block/vold/179\:17 /mnt/extSdCard ext 4 noatime,nosuid,nodev,discard,noauto_da_alloc,journal_async_commit,erros=panic wait,check. This unfortunately did not work, but kernel log gave me Cannot mount filesystem on /dev/block/vold/179\:17 at /mnt/extSdCard.
EDIT2: stupid of me not to use /dev/block/mmcblk1p1, which is the partition of the µSD-Card. This way I was now able to mount the µSD-Card by modifying the fstab.sdmk4x12 file.
EDIT3: after I was able to mount the µSD-Card, the problem of how to mount the image remains. I've modified the line where it mounts the userdata partition. The line is the same as the one from EDIT1+2, but uses the image /storage/extSdCard/userdata.img to mount it to /data. But I guess it apparently fails to mount the image. The device boots up, but displays some error, stating the userdata partition is damaged. It also gives me the option to reset it, but of course this only affects the userdata partition, and as soon as I reboot, it is trying to mount my image again, fails and shows me this error again.
I have found a workaround. Instead of trying to mount the image, I just copied all files from /data onto the partition on the µSD-Card, and mounted the partition as /data in the fstab.sdmk4x12 (i.e., mounting /dev/block/mmcblk1p1 as /data). All apps etc. will now be stored on the partition on the µSD-Card.
Im working on "mount ntfs sdcard"
That is problem:
- If i mount sdcard to another folder than /mtn/sdcard then my sdcard working find
- If i mount it to /mnt/sdcard then android not except it : " The SDcard is not currently mounted"
In adb shell i type mount command and see that my SDcard is mounted to /mnt/sdcard
But infact SDcard folder cannot accessable.
I think android doesnt except mount ntfs sdcard on /mnt/sdcard because it programed to mount vfat sdcard on /mnt/sdcard.
Now the question: where i can find mounting code or mounting procedure of android when we insert SDcard? i want to modify it to accept ntfs sdcard.
P/S: im on GB 2.3.6
This is a very specific question, I doubt you will get an answer here. You might want to try to locate it yourself from the source code which could be found here:
https://sites.google.com/a/android.com/opensource/download
I did some googling and found this:
http://cateee.net/lkddb/web-lkddb/NTFS_FS.html, you might need to modify it.
On Android, the mounting of the sdcard is managed by the vold daemon.
If you want a stable system, you likely need to either get vold to manage your custom mount, remove vold from the system and do it's entire job yourself, or somehow get it and your custom solution to stay out of each other's way.
Lots of custom ROMs have used vold in different ways - to partition an sdcard and add a unix-style filesystem for storing apps, to put an entire alternate android installation on an sdcard or tablet internal storage area, etc. You might get some ideas by looking at those, reading their development discussion history, etc.
Is it possible to find out volume label of SD card inserted into Android device?
I understand that Android is designed to have just one "external storage" (as returned by Environment.getExternalStorageDirectory()), but there are quite a few devices in the wild that have internal flash as "external storage" and an SD card mounted under that or even wilder combinations (see this other question). It is possible to enumerate these additional devices by reading /proc/mounts, but we need something to identify them to the user. Is there any chance to get to their volume labels?
I checked that Linux vfat driver ignores the volume label dentry altogether and that blkid from util-linux reads the vfat itself. I also checked that, at least on device I have, the block device of the SD card has mode 660 and owner root.root, so I can't do that. So basically it boils down to whether there is any utility that could read it available.
I have found a solution.
The easiest solution is to build busybox and use it like this:
busybox blkid
Complicated solution is to find blkid for Android and find what you need in its source code (blkid_dev_devname function).
i don't know how it works exactly in android, but in linux i have kernel message about mounting sd-card, where volume name specified. You can try dmesg and cat /sys/devices/mmc... (or somethong like that)
Try to parse output of blkid command. It works for me, but I'm not sure if it is a firmware depended feature or not. I got permission denied with this command on AVD.
I don't know if this can help you: if you use the DDMS you can see the folders of the system. In my case, I found the sd card in: /mnt/media_rw.
You can get more information here and here
I hope it helps.
I have an application that writes important data to the SDCard and encrypts it using AES, which later will be used by a desktop application. I have noticed that if I do not unmount the SDCard from the Settings menu sometimes the files don't get written at all, or are corrupted.
Is there anyway in Android 2.1 that I can unmount the SDCard programmatically? Because I'm pretty sure that from time to time the users will forget to do this, and I'll be the one fixing the problems and I really don't want this.
If this is not possible,what Linux command should I use to unmount the SDCard? Since the application will run on some tablets that have a rooted OS.
You should unmount what's using the sdcard in the proper order, for example
umount /mnt/sdcard/.android_secure
umount /mnt/sdcard
or, probably synchronizing the buffers with the filesystem would be enough
sync; sync
On the emulator, I can unmount the SD card from the Settings.
I can then mount it on my OS, then unmount it normally.
I haven't been able to figure out how to re-mount it then on the emulator (without rebooting it).
hints:
the adb command remount is unrelated: it's about /system
the emulator command is unrelated: it's only about starting the emulator
mounting the SD card in two places of course messing everything up (I tried)
more:
mount outputs the following:
/dev/block//vold/179:0 /sdcard vfat rw,dirsync,nosuid,nodev,noexec,uid=1000,gid=1015,fmask=0702,dmask=0702,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
trying to mount again from the shell after unmounting it, using the same options as above, gives a segfault
no idea why the double slash in block//vold, I guess it's just a typo
The developers guide suggests that this isn't possible:
SD Card Emulation
You can create a disk image and then
load it to the emulator at startup, to
simulate the presence of a user's SD
card in the device. To do this, you
can use the android tool to create a
new SD card image with a new AVD, or
you can use the mksdcard utility
included in the SDK.
The sections below describe how to
create an SD card disk image, how to
copy files to it, and how to load it
in the emulator at startup.
Note that you can only load disk image
at emulator startup. Similarly, you
can not remove a simulated SD card
from a running emulator. However, you
can browse, send files to, and
copy/remove files from a simulated SD
card either with adb or the emulator.
The emulator supports emulated SDHC
cards, so you can create an SD card
image of any size up to 128 gigabytes.
While Android will unmount the SD card, the emulator process keeps the backing file open.
$ ls -go /proc/`pidof emulator`/fd | grep sdcard.img
lrwx------ 1 64 2010-05-13 01:50 10 -> /home/x/.android/avd/WithSD.avd/sdcard.img
Someone more familiar with QEMU may be able to provide further insight but, if I were you, I would just try to use NFS to solve this problem.
I tried going to Settings and unmounting the SD card and this worked fine. Give it a try; remounting it is quite simple.
Doesn't seem like this can be done via adb/cli though.