I have a course project that involves setting up a device driver on Android. I have previously worked with device drivers in the Linux kernel and we used two commands to initialize the device and make a node: insmod and mknod
Now when I launched the emulator shell using adb shell, I was able to use insmod but mknod did not work. I have tried to find alternatives but was not lucky.
From what I know, mknod in the Linux kernel lists the device under the /dev directory and allows user programs to read/write to it by using its file ops.
So what is its alternative for Android?
Perhaps, the android device you're using don't have mknod command. It need to be supported from rootfs, usually Android rootfs are built using busybox. Most probably, mknod was dropped from busybox config. Possible option could be, use custom Android image where you've mknod installed.
Related
I have this development board Open-Q 820
It is running an Android 7.0 based on some sources from CodeAurora (that seem based on AOSP sources). Seems it uses proprietary bootloader that can not be changed. I need to access GPIO (/system/class/gpio) from my android app to control an external device. Problem is I can not do this from android app - seems only root can access this files.
I can call "adb root" command from PC and then call from "adb shell" something like
echo 0 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio0/direction
echo 1 > /sys/class/gpio/gpio0/value
and it is working. But I need to do the same from my android app. I know how to access terminal and su from android app. I just dont know how to root custom device. I tried to install SuperSU.apk app and its corresponding su native app manually. It starts and says it need to update su binaries. After installing binaries and reboot the system then it becomes broken - infinite android logo. If I not install binaries update then SuperSU can grant permissions to my app but actully app still can not use su (I dont know why - I use this library inside my app: https://github.com/Chrisplus/RootManager). And after reboot SuperSU not working longer.
So may be you know some SuperSU alternatives (Knigroot not working too) or steps how to correctly install some superuser management app. Or may be I can use su directly (I tried but my app has not rights to access /system/xbin/su). Or may be I can make /sys/class/gpio accessible by android apps somehow (I tried chmod 777 on it - not works). May be some SElinux rights, but I have no experience with this.
Thank you
Magisk helped me. Since it is have option to patch custom boot image. I used this option and now root access works.
Directories /run/user/1000/gvfs and ~/.gvfs are emtpy and non-existing, respectively. My graphical file manager (Thunar) is able to detect and access the internal and external memory of the device.
Command gvfs-mount -l yields:
Volume(0): SAMSUNG Android
Type: GProxyVolume (GProxyVolumeMonitorMTP)
Mount(0): SAMSUNG Android -> mtp://[usb:002,003]/
Type: GProxyShadowMount (GProxyVolumeMonitorMTP)
Where can I find the mount point of the device to access it from the command line? I'm using Ubuntu 16.04.
You also need to install gvfs-fuse:
gvfsd-fuse maintains a fuse mount to make gvfs backends available to POSIX applications. The mount point for the fuse filesystem is provided by the [PATH] argument.
gvfsd-fuse is normally started by gvfsd(1). In this case, the mount point is $XDG_RUNTIME_DIR/gvfs or $HOME/.gvfs.
Here is a great explanation:
/run/user/$uid/gvfs or ~$user/.gvfs is the mount point for the FUSE interface to GVFS.
...
The GVFS-FUSE gateway makes GVFS filesystem drivers accessible to all applications, not just the ones using Gnome libraries.
Execute following commands
sudo apt install gvfs-fuse
pkill thunar
pkill gvfs
and run Thunar again.
Just had the same issue with Android 11. Solved it by going into the phone's 'Settings - Connected devices - USB' and selecting 'File Transfer' which was apparently disabled by default.
I am trying to run some ARM assembly codes on Snapdragon 810 development board to evaluate performance on Cortex-A53 and A57 processors. My codes are nothing to do with android applications and they are C/Assembly coeds. Moreover, I want to get remote access to the board preferably via SSH and run gcc commands. The board default OS in Android Lollipop and my first intention was to install Linux on it to make things work desirably. However, Qualcomm customer support informed me that Linux isn't supported by this board and I have to deal with Android.
I've already searched over various forums. Some of them suggest to root the Android device, install QuickSSHD or SSHDroid on the device and simply SSH to it. However, I am not sure if the provided console has the capability of running gcc commands, generating executable and running it. Others, suggest to generate executable using cross-compilation and push the executable via adb console and run it on the Android device. This approach makes more sense, but I need to have remote access via SSH to the board and edit my code on the device continuously.
My question is, what is the best and easiest approach to get remote access via SSH to this device, compile and run C/ARM Assembly code, transfer files and get the real timing of my codes?!
Cross compile is the easiest option to generate the executable. Else you will have to port GCC to the target first. Don't even bother.
And Adb is a lot better when dealing with Android devices as you need not install any additional applications/executables to get it working. Adb can work on TCP connection as well. So there is no need of SSH for the task. And if the device is rooted, "adb root" followed by "adb shell" would give you the root console.
I'm planning to build an automated system for deploying an Android build to various devices, in order to make development for multiple platforms a bit more comfortable. Is there a way to get the sdk version of a connected device through android shell or adb?
There will be a computer to which several test devices is connected, and I was planning to write a script which will fetch the correct build for each of those from a build-server, install the different apks on their respective devices, launch them and collect log info, to be made available through some other program whose specifications are beside the point.
The point is that I need to know the sdk version each device is running to install the correct apk, and I was hoping I could get this through adb, but I can't seem to find a way to access it short of building a tiny app, compatible with all versions, whose sole purpose would be to output android.os.Build.VERSION.SDK or similar somewhere my script could read it.
you can use this command:
adb shell grep ro.build.version.sdk= system/build.prop
It will output something like this:
ro.build.version.sdk=10
adb shell getprop ro.build.version.sdk
Note #Tim: this works even on phones without grep support on all host OS :-). (i.e. on old phones where toolbox does not support grep you you need to have busybox on your phone).
I also discovered a way to get the exact version of Android e.g. 4.2.2 based on the following web article http://xayon.net/looking-for-android-version-with-adb/ You need to be using a unix-like operating system - Linux and Mac OSX are fine, and windows users can use cygwin or equivalent.
At a command line:
echo version=$(adb shell getprop |awk -F":" '/build.version.release/ { print $2 }')|tr -d '[]'
Here is the result for my Nexus 4:
version= 4.2.2
I think you can by accessing the device with adb shell - change directories to position you at system and do a cat of build.prop. Here you will find for instance, ro.build.description=google_sdk-eng 2.2, ro.build.version.release=2.2 etc
It'd be nice to have the "Swiss Army knife" of BusyBox on my emulator. It would also be nice to have full root access. Does anyone have any experience doing this? I'm not familiar with qemu; is this even possible?
Update: The emulator has root by default (accessed via the adb shell command). Does anyone know where I can easily obtain a pre-built busybox binary?
The emulator is not set to secure mode, so it's adb shell should be a root shell.
There are several android builds of busybox, for example cyanogen alternative versions of Android use it to augment toolbox (which is Android's own limited re-implementation of the same concept under a non-gpl license). You should be able to get it from the cyanogen repositories and build it from source, or it's possible that just extracting the binaries from a same-android-version cyanogen update.zip would work (it may be in a compressed file system inside the update though)
There were also some writeups from pioneers who discovered the accidental root shell on the original G1 release and installed quite a bit of debian arm.